Basic Exam Flashcards

Question 1

Q

What is the half life of Flumazenil?

Why is this important?

Answer

A

Half Life:

Midazolam: 1.7 - 2.6 hours (102 minutes - 156 minutes)

Flumazenil: 0.7 - 1.3 hours (42 min - 78 minutes)

Significantly shorter half life than benzodiazepine agonists.

This can lead to the recrudescence of sedation from benzodiazepines following the elimination of flumazenil.

Therefore, when administering flumazenil, careful attention needs to be paid to its duration of action relative to that of the benzodiazepines taken by the patient, and additional doses of flumazenil should be available.

Question 2

Q

What is the mechanism of action of Flumazenil?

Answer

A

*Caveat to Mechanism of Action*

Note that although flumazenil is generally considered a benzodiazepine antagonist, it exhibits a partial agonist effect.

In one study, propofol was potentiated by giving high doses of flumazenil, suggesting flumazenil has a mixed or partial agonist effect.

Question 3

Q

What is the half life of the common benzodiazepines?

Alprazolam, Diazepam, Lorazepam, Midazolam, and Temazepam

Answer

A

Half Life of Other Benzodiazepines (MALTD)

Midazolam is 1.7-2.6 hours (2 hours)

Alprazolam is 6-27 hours (A = Afternoon)

Temazepam is 10 hours (Tem = Ten)

Lorazepam is 11-22 hours (L = eLeven)

Diazepam is 20-50 hours (D = ~ 1 day)

Question 4

Q

For Nitrous Oxide, a full tank will read:

What volume?

What pressure?

When will the pressure start to drop?

Answer

A

A full tank of N2O contains 1590 L at a pressure of ~745 psig.

Pressure within a tank of N2O will remain at ~745 psig until all liquefied gas is used up which is when the tank is ~16% full (253 L).

Question 5

Q

What acid base disturbances are common with different diuretics?

Acetazaloamide?

Thiazide?

Loops?

Potassium Sparing?

Answer

A

Thiazide and loop diuretics can cause an Hypokalemic Hypochloremic metabolic alkalosis.

Acetazolamide and potassium sparing can cause a hyperchloremic metabolic acidosis.

Question 6

Q

How does hyperventilation affect electrolytes?

Calcium?

Potassium?

Phosphate?

Sodium?

pH?

HCO3?

Chloride?

Lactate?

Answer

A

Respiratory alkalosis (ETCO2 of 30-35), such as from hyperventilation, can cause electrolyte abnormalities such as hypocalcemia, hypokalemia, and hypophosphatemia.

Loss of CO2 by 10 mmHg

Rise in pH (0.1)

Decreased HCO3 (2.0 mEq/L)

Decreased Potassium (0.4 mEq/L) - After will slowly return to normal

Decrease in Sodium

Increased Chloride (Balanced decrease in Bicarb)

Increased lactate (Balanced decrease in Bicarb)

Question 7

Q

What is the relationship between hyper/hypoventilation and calcium levels?

(Explain the physiology)

Answer

A

Hypocalcemia can occur with respiratory alkalosis.

In response to alkalosis, hydrogen ions bound to negatively charged plasma proteins, such as albumin, are released.

Calcium, being positively charged, can then bind to albumin and other proteins decreasing the serum calcium concentration (particularly the free/ionized, active fraction). This is the mechanism behind paresthesias that occur with hyperventilation.

Question 8

Q

What are the main determinants of myocardial oxygen demand?

Answer

A

1. Wall tension

2. Heart rate

3. Contractility

Question 9

Q

What is the formula for wall tension?

Answer

A

Wall tension (T) = (P * r) / (2 h)

P is the pressure within the ventricle

r is the radius of the ventricle

h is the thickness of the ventricular wall (Increase seen in hypertrophy)

Question 10

Q

What is the downside to developing left ventricular hypertrophy?

Answer

A

The ventricle hypertrophies to compensate for the increased wall tension due to pressure or volume overload, such as with aortic stenosis. However, this change comes at a cost. The hypertrophied ventricle is not as compliant due to increased diastolic pressures in the ventricle. This leads to a decrease in preload*, and the hypertrophied ventricle is now more *dependent on atrial contraction to maintain LVEDV

ex: (Atrial fibrillation with diastolic heart failure is a horrible combination)

Question 11

Q

What are the two determinants of acoustic impedence of ultrasound?

Answer

A

Acoustic Impedance (two factors determine)

1. Density of the medium(This is the main one)

2. Propagation speed of sound through the medium

Acoustic impedance is the product of the density of a medium and the propagation speed of sound through that medium. Ultrasound reflections that occur at the interface of different mediums are due to the changes in acoustic impedance. Since propagation speed changes slightly between biological mediums, acoustic impedance is primarily dependent upon density.

Question 12

Q

How does gentamicin affect neuromuscular blockade?

What is the mechanism behind this?

Answer

A

Prolongs neuromuscular blockade

Gentamicin inhibits prejunctional acetylcholine release and depresses postjunctional receptor sensitivity to acetylcholine, thus prolonging paralysis in a patient who received it along with a muscle relaxant.

It is believed that aminoglycoside antibiotics antagonize calcium ions by means of its involvement in the process of acetylcholine release by nerve impulses.

Question 13

Q

What are all the antibiotics that can prolong neuromuscular blockade?

Answer

A

Aminoglycosides

Lincomycin, Clindamycin, Streptomycin, kanamycin, tobramycin, neomycin, and gentamicin

Polymyxins

Tetracyclines

Question 14

Q

Muscarinic receptor agonists can act through two mechanisms, directly on the muscarinic receptor or indirectly by inhibiting the breakdown of ACh causing more ACh to be available to bind to the muscarinic receptor.

1. What are the direct acting agents are choline esters?

2. And what are the alkaloids?

3. What are the anticholinergics?

Answer

A

The direct acting agents are choline esters (ACh, methacholine, carbachol, bethanechol)

direct acting agents have few clinical applications due to their very short half and longer activity can be achieved by methylating the choline moiety.

Alkaloids (pilocarpine, muscarine, arecoline or acetylcholinsterase inhibitors).

The indirect acting agents are acetylcholinesterase inhibitors (physostigmine, neostigmine, pyridostigmine, edrophonium, and echothiophate). These medications are often used to improve neuromuscular function in disease states where weakness occurs such as myasthenia gravis or to help reverse the action of nondepolarizing neuromuscular blocking agents.

Anticholinergic drugs are used commonly in anesthesia practice. These medications inhibit the action of ACh by reversibly binding at the muscarinic receptor. Antimuscarinic drugs used in anesthesia practice are atropine, scopolamine, and glycopyrrolate. Both atropine and scopolamine cross the blood-brain barrier, which can result in inhibition of vagal outflow from the central nervous system. At low doses, vagal outflow can potentially be augmented.

Question 15

Q

You have your line isolation monitor alarming. What is the next step?

Answer

A

When the line isolation monitor alarms, the first step should be to unplug the most recent electronic device that was plugged in.

Question 16

Q

What portion of the spinal cord is perfused by the anterior spinal artery?

How many are their?

What vessel is this from?

Answer

A

A single (not paired) anterior spinal artery supplies the anterior two-thirds of the spinal cord.

The spinal cord blood supply is anatomically divided into an anterior and a posterior blood supply. The anterior two-thirds of the spinal cord, primarily responsible for motor function, is perfused by the anterior spinal artery (ASA), which originates from the vertebral arteries and receives contributions from various radicular vessels that arise from intercostal arteries.

Question 17

Q

Is the posterior spinal artery paired?

What is the perfusion to the posterior spinal artery?

What does it arise from?

Answer

A

Two posterior spinal arteries (PSA) stem from the vertebral or posterior inferior cerebellar arteries (PICA). They comprise the blood supply to the posterior one-third of the spinal cord, primarily responsible for sensation, while concurrently receiving intercostal radicular vessel contributions.

Question 18

Q

What is the origination spinal levels of Artery of Adamkiewicz?

(List the regions from most to least common)

Answer

A

The artery of Adamkiewicz a radicular vessel contributing to anterior spinal cord blood supply

Most commonly originates within the T9 - T12 region

Followed by the L1 - L5 region

least commonly, within the T5 - T8 region

Question 19

Q

Compare adults vs. infants in terms of:

Spinal cord* vs. *Dural Sac Ending

Answer

A

In adults

Spinal cord ends at about L1-L2 (Conus Medullaris)

Dural sac ends at about S1-S2.

In an infant, these landmarks are shifted slightly caudad (Inferior)

Spinal cord ending at L3-L4

Dural sac terminating at S3-S4

Question 20

Q

When performing a spinal blockade in an adult, the iliac crest is commonly used as a landmark as it generally corresponds to the level of the L4 interspace is known as What Anatomical Landmark?

Answer

A

Tuffier’s line

Question 21

Q

What are the 3 drugs that can decrease post-operative delirium with Ketamine administration?

Answer

A

Benzodiazepines, propofol, and barbiturates can decrease ketamine-induced emergence delirium.

An important consideration when using ketamine relates to the high incidence of psychomimetic reactions early in the recovery period. The most common reactions include hallucinations, nightmares, altered cognition, and altered short-term memory. Repeated doses of ketamine may decrease the severity and incidence of emergence delirium, but one of the most effective strategies for prevention of emergence delirium is the use of midazolam approximately five minutes prior to an induction with ketamine.

Question 22

Q

How does magnesium and Calcium levels affect neuromuscular blockade?

Answer

A

Hypocalcemia potentiates neuromuscular blockade because calcium is important for the release of vesicles containing acetylcholine from nerves at the neuromuscular junction.

When calcium levels are low, less acetylcholine is released.

With less acetylcholine being released there is less competition at the acetylcholine receptor and neuromuscular blockers have a greater effect.

Hypermagnesemia acts similarly by blocking calcium from entering alpha motor neurons and preventing the release of some of the acetylcholine containing vesicles.

Question 23

Q

How do anti-convulsants affect neuromuscular blockade?

Answer

A

*Shorten Non-Depolarizing Blockade:**
Anticonvulsants (e.g. phenytoin, carbamazepine)

Question 24

Q

What effect does Ketamine have on neuromuscular blockade?

Answer

A

Prolongs

Question 25

Q

What is the order or potentiating volatile anesthetics for prolonging neuromuscular blockade?

Why is this physiologically seen?

Answer

A

Potentiation from greatest to least for volatile anesthetics is:

desflurane* > *sevoflurane* > *isoflurane.

Desflurane is a volatile anesthetic with a low blood gas partition coefficient of 0.42.

The low blood gas coefficient means that very little desflurane is dissolved in tissues, but that desflurane is able to rapidly equilibrate with tissues resulting in quick onset and termination of effects.
This rapid equilibration into tissues including muscle is the reason why desflurane potentiates neuromuscular blockade more than other volatile anesthetics.
The location of potentiation is likely at the neuromuscular junction and occurs in a dose dependent fashion.

Question 26

Q

Mechanical ventilation can be categorized by what three variables? Explain them

Answer

A

Ventilators need “TLC”

Mechanical ventilation can be categorized by three variables

1. Trigger - What initiates the breath and depends on ventilatory drive

2. Limit - Governor of PPV and depends on ventilatory requirements related to how much flow* and *volume are required to satisfy metabolic demands

Cycle - What terminates the inspiratory phase and depends on the duration and ratio of inspiratory time to total breath cycle duration.

Question 27

Q

How does Morphine improve Coronary Perfusion?

Answer

A

Morphine improves coronary perfusion through a reduction in preload and a reduction in end-diastolic pressures (EDP) in the ventricles.

The EDV is proportional to the EDP generated within the ventricle.

The RV is perfused during both systole and diastole whereas the LV is perfused during diastole only.

Right-sided coronary perfusion pressure during systole is = (aortic systolic pressure - RVEDP).

Left-sided coronary perfusion pressure is the difference between (aortic diastolic pressure and left ventricular end-diastolic pressure (LVEDP)).

Coronary perfusion pressure is improved by REDUCING both RVEDP and LVEDP.

Question 28

Q

What is the first symptom during central nervous system toxicity of local aneshetics?

Answer

A

Central nervous system toxicity is first noted by circumoral and tongue numbness.

Visual and auditory disturbances (tinnitus) then follow.

The clinical scenario then progresses to dizziness/lightheadedness, muscular twitching, unconsciousness, and seizure activity. These clinical signs may then be followed by cerebral edema, increased intracranial pressure, coma, respiratory arrest, and ultimately cardiovascular depression and death. Patients who are premedicated with anticonvulsants, such as benzodiazepines or barbiturates, may have masked CNS symptoms and develop cardiovascular depression before other signs are apparent.

Question 29

Q

Areas of regional anesthesia from highest to lowest vascularity include (List the order of greatest to least)

Answer

A

intravenous

tracheal

intercostal

caudal/paracervical

epidural

brachial plexus

sciatic/femoral

spinal

subcutaneous

Intercostal > Caudal > Epidural > Brachial Plexus > Lower Limbs > Sub-Q “IT - ICE BaLLS” is the mnemonic

Question 30

Q

Rank the Areas of regional anesthesia from highest to lowest vascularity.

Answer

A

Areas of regional anesthesia from highest to lowest vascularity include:

intravenous > tracheal > intercostal > caudal/paracervical > epidural > brachial plexus > sciatic/femoral > spinal > subcutaneous.

Question 31

Q

What is the possible consequence of using lidocaine through spinal?

Answer

A

Lidocaine has been linked to cauda equina syndrome, causing urinary and fecal incontinence as well as gait disturbances.

This association has been documented in the setting of high concentration (5%) intrathecal lidocaine administered via narrow lumen (e.g. 27 gauge) catheters. The slow administration of 5% lidocaine through these catheters allows for pooling of the drug in the region of the cauda equina. This form of local neural toxicity may be due to demyelination.

Question 32

Q

If you have a desiccated CO2 absorbent, what is the byproduct of desflurane?

Of sevoflurane?

Answer

A

Carbon monoxide and heat are produced from the degradation of anesthetic agents in the presence of desiccated carbon dioxide absorbent. Among today’s volatile anesthetics, degradation of desflurane produces the most carbon monoxide.

Sevoflurane = Compound A

Question 33

Q

When would you see a Saphenous Nerve injury?

Where is the symptoms anatomically?

Answer

A

Injury to a saphenous nerve can cause numbness, pain, and/or paresthesias along the medial lower leg.

Perioperative saphenous nerve injury is relatively uncommon but, due to its close proximity to the great saphenous vein, is a known complication of saphenous vein harvest (e.g., vein graft harvest for coronary artery bypass grafting) or saphenous vein stripping.

Rarely, saphenous nerve block can also cause temporary or permanent nerve injury.

Damage to the saphenous nerve may result in temporary or permanent cutaneous sensory loss, pain, or paresthesias.

Anatomy:

Major sensory branch of the femoral nerve that is primarily responsible for cutaneous sensation of the medial lower leg

Question 34

Q

What does the Sciatic Nerve split into at the area of the knee?

Answer

A

Tibial nerve

Common Peroneal nerve

Question 35

Q

What does the superficial peroneal nerve innervate (Include MOTOR and SENSORY)?

Answer

A

Mixed sensory and motor nerve that innervates the peroneus longus and peroneus brevis muscles (which allow foot eversion)

Provides sensation to the lateral lower leg and most of the dorsum of the foot.

Question 36

Q

When are common peroneal nerve injuries seen?

Answer

A

Common peroneal nerve injury is the most common isolated mononeuropathy of the lower extremities.

Perioperative injuries can occur due to knee hyperflexion (e.g., during lithotomy position in stirrups or boots).

Excessive hip flexion leading to a sciatic nerve stretch injury can also damage nerve fibers prior to their division into the common peroneal nerve.

Question 37

Q

What is the movement responsible for deep peroneal nerve?

What is the sensory innervation of deep peroneal nerve?

What type of injury, and symptom is common from deep peroneal nerve injury?

Answer

A

Mixed sensory and motor nerve that innervates many major lower leg muscles which are primarily responsible for foot dorsiflexion.

Provides cutaneous sensation to a small patch of skin between the first and second toes.

Isolated injury to this nerve is most commonly caused by trauma to the lateral knee and typically leads to foot drop.

Question 38

Q

Tibial Nerve

Branch of what nerve?

What movement does this control?

Answer

A

The tibial nerve is a motor and sensory branch of the sciatic nerve.

It innervates the lower leg posterior compartment muscles primarily responsible for foot plantar flexion.

The tibial nerve also provides cutaneous sensation to the posterolateral lower leg and lateral foot.

Tibial nerve injury is most commonly caused by trauma to the lower leg or ankle.

Question 39

Q

Expected changes in pH, HCO3, and PaCO2 in:

Acute Respiratory Acidosis

Chronic Respiratory Acidosis

Chronic Respiratory Alkalosis

Answer

A

Acute respiratory acidosis should demonstrate a pH decrease of 0.05 and an HCO3- increase of 1.0 mEq/L per acute 10 mm Hg increase in PaCO2.

Chronic respiratory acidosis, pH nearly normalizes, and HCO3- concentrations increase 4-5 mEq/L per 10 mm Hg sustained increase in PaCO2.

Respiratory alkalosis becomes chronic, pH nearly normalizes and HCO3- decreases 5-6 mEq/L per 10 mm Hg sustained decrease in PaCO2.

Question 40

Q

What is the most common variant of pseudocholinesterase deficiency?

Answer

A

Approximately 20 genetic variants of the BCHE gene exist with the A- and K-variants being the most common.

Question 41

Q

What medicine is an anticholinesterase used to treat refractory glaucoma by causing miosis?

Since it inhibits BCHE, systemic absorption can cause up to a 95% decrease in BCHE function, thereby potentiating the effects of succinylcholine.

Answer

A

Echothiophate

Question 42

Q

What are the 4 phases of diastole?

Answer

A

There are four phases during diastole:

Isovolumetric relaxation: this phase begins with the closure of the aortic valve and continues till the opening of the mitral valve. During this time, the left ventricle is relaxing, however there is no change in the ventricular volume (isovolumetric).

Early rapid filling: this phase begins with the opening of the mitral valve. The left ventricle begins to fill with blood from the left atrium. The flow of blood is driven by the transmitral pressure gradient. This phase contributes the largest volume of blood to the left ventricle during diastole.

Diastasis (slow filling): as the left ventricle fills, the pressure difference between the left ventricle and atrium decrease. This slows down the filling considerably, and contributes approximately 5% of the preload. This phase occurs mid-diastole.

Late rapid filling (atrial contraction): the left atrium contracts, ejecting additional blood into the left ventricle. This phase can contribute 15-20% of the preload. Atrial contraction is the last phase of diastole. The mitral valve closes after the atrial contraction.

Question 43

Q

Why does the FA/FI curve rise faster for nitrous oxide compared to desflurane?

Answer

A

The absorption of nitrous oxide is augmented by the concentration effect, making the rate of absorption faster than desflurande despite their similar blood gas partition coefficients.

Question 44

Q

What are the 3 forms in which CO2 is transported?

Answer

A

Carbon dioxide is transported in the blood as:

1. Dissolved CO2

Carbon dioxide is 10 times more soluble in blood than oxygen: 0.031 mmol/L/mm Hg versus 0.003 mmol/L/mm Hg, respectively.

2. Bicarbonate *Majority*

This occurs because red blood cells and vascular endothelium contain carbonic anhydrase, an enzyme used to convert carbon dioxide to bicarbonate. The enzyme also catalyzes the reverse reaction. In either case, a transient intermediate, carbonic acid, is created.

Bicarbonate production: H2O + CO2 ↔ H2CO3 ↔ H+ + HCO3-

3. Carbamino compounds.

Carbamino compounds also transport carbon dioxide in the blood. Carbamino compounds are produced from a reaction with proteins. The small amount of CO2 transported in this manner mostly interacts with hemoglobin proteins and to a lesser extent plasma proteins.

Carbamino compound production: R-NH2 + CO2 → R-NH-CO2- + H+

Question 45

Q

Which blood product is most likely to cause transfusion related sepsis?

Answer

A

Transfusion-associated sepsis is the third leading cause of transfusion-related deaths in the United States and is most commonly caused by bacterial infection from contaminated platelets.

Unlike other blood products, platelets are stored at room temperature which leads to increased bacterial growth.

Question 46

Q

What urine to plasma osmolar ratio indicates pre-renal oliguria?

Answer

A

A urine-to-plasma osmolar ratio (UOSM : POSM) >1.5 indicates prerenal oliguria (generally secondary to hypovolemia).

The UOSM : POSM is used to assess the tubular response of the kidneys to dehydration or hypovolemia. In this setting of prerenal oliguria, this formula evaluates the kidneys’ ability to retain Na+ and water and produce highly concentrated urine by increasing urine osmolality above 450 mOsm/kg.

By comparison, normal plasma osmolality is 280-300 mOsm/kg.

The UOSM : POSM indicates the kidneys’ ability to concentrate urine. Tubular damage and acute renal failure, therefore, may be represented by a decreased ratio.

The UOSM : POSM can also decrease with the administration of diuretics. As an aside, isosthenuria is a UOSM : POSM equal to 1.

Question 47

Q

MOA of:

Hydrochlorothiazide?

Furosemide?

Spirinolactone?

Answer

A

HCTZ = It works by blocking the Na/Cl co-transporter in the DCT

This causes inhibition of sodium reabsorption in the distal convoluted tubules, thereby increasing the excretion of both sodium and water.

Furosemide = Na/K/Cl in Loop of Henle Blocked

Spirinolactone = Blocks aldosterone receptor in DCT

Question 48

Q

Which of the following findings on physical examination is generally considered the BEST predictor for difficult tracheal intubation in morbidly obese patients?

Answer

A

Three factors obtained by history or physical exam that correlate with difficult intubations in obese patients include

1. Increased neck circumference **Best single indicator**

2. Mallampati class III or IV airway

3. Presence of obstructive sleep apnea.

In general, increased age, male sex, TMJ pathology, and abnormal upper teeth also correlate with difficult intubations.

Question 49

Q

What are the common chemo toxocities for?

Cisplatain, Carboplatin?

Answer

A

Acoustic nerve damage

Nephrotoxicity

Question 50

Q

Chemotoxicity for:

Vincristine

Answer

A

Vincristine: peripheral neuropathy

Question 51

Q

Chemotoxicity for:
Bleomycin, Busulfan

Answer

A

Pulmonary fibrosis

Question 52

Q

Chemo toxicity for Doxorubicin?

Answer

A

Cardiotoxicity

Question 53

Q

Chemo toxicity for Trastuzumab?

Answer

A

Cardiotoxicity

Question 54

Q

Chemo toxicity for Cyclophosphamide?

Answer

A

Hemorrhagic Cystitis

Question 55

Q

Chemo toxicity for 5-FU, 6-MP, methotrexate?

Answer

A

myelosuppression

Question 56

Q

What are the contraindications to succinylcholine therapy?

Answer

A

BRIGMS(S) “Brigham’s”

Burns

Relaxants - Chronic

Immobility (Prolonged)

Guillain-Barre Syndrome

MS

Stroke & Spinal Cord injury

Spinal cord injury

Question 57

Q

What are the 5 triggers for vomiting?

Answer

A

The vomiting center is stimulated by:

1) the chemotactic trigger zone (CTZ) located in the medulla
2) gastrointestinal tract
3) pharynx
4) visual centers
5) mediastinum

Question 58

Q

What is the onset time of Scopalamine patch?

What are the side effects of it?

Answer

A

Anticholinergics (e.g., scopolamine patch):

Needs to be applied prior to going back to the operating room due to its 2 to 4 hour onset time.

Can cause visual changes, dry mouth, and dizziness.

Question 59

Q

Droperidol:

Class?

Mechanism?

Dose?

Answer

A

Dopamine-2 receptor antagonist (e.g., droperidol, metoclopramide): droperidol is effective as an anti-emetic.

Recommended dosing is 0.625 to 1.25 mg at the end of surgery

Question 60

Q

What are the independent criteria for:
MELD Score?

vs.

Child’s Pugh?

Answer

A

Mnemonics to help differentiate MELD from Child-Pugh:

MELD: “I Crush Several Beers Daily” for INR, creatinine, sodium, bilirubin, dialysis

Childs-Pugh: “Pour Another Beer At Eleven” for PT, Ascites, Bilirubin, Albumin, Encephalopathy

Question 61

Q

What is a normal Strong Ion Difference?

What is the equation?

Answer

A

Normal human plasma has a SID of 40-44 mEq/L.

SID = ( [Na+] + [K+] + [Ca2+] + [Mg2+] ) - ( [Cl-] + [A-] )

Question 62

Q

Plasma pH Theories are determined by what 3 independent factors?

Answer

A

The concept of SID proposes that plasma pH is determined by three independent factors:

1. PCO2

2. SID

Strong ion difference represents the difference between the charge of plasma strong cations (sodium, potassium, calcium, magnesium) and anions (chloride and other strong anions (A-) such as lactate, sulfate, ketoacids, and nonesterified fatty acids).

3. Atot.

The latter (Atot) represents the total plasma concentration of nonvolatile buffers (e.g., albumin, globulins, and inorganic phosphate).

Question 63

Q

Large volume saline:

What happens to:

1. Bicarbonate?

2. pH?

3. SID?

4. Anion Gap?

5. Chloride level?

Answer

A

Large volumes and rapid administration of normal saline can produce a non-anion gap hyperchloremic metabolic acidosis. Associated laboratory values include decreased plasma HCO3-, increased plasma Cl-, decreased SID, and a normal anion gap.

Question 64

Q

Why is subendocardial ischemia seen more commonly than epicardial transmural injury?

Answer

A

Subendocardial ischemia is more commonly seen than transmural injury because the small capillaries and arterioles at the subendocardial level are subject to occlusive high intraventricular pressure.

The epicardial coronary arteries in comparison are distant from the high intraventricular pressures and thus generally unaffected unless acute occlusion from a thrombus, spasm, or embolism occurs.

Answer 65

A

≥ 0.1 mV in all leads other than leads V2–V3 where the following cut-points apply:

≥ 0.2 mV in men > 40 years

≥0.25 mV in men < 40 years

≥ 0.15 mV in women

Answer 66

A

New horizontal or down-sloping ST depression ≥ 0.05 mV in two contiguous leads and/or
T inversion ≥ 0.1 mV in two contiguous leads with prominent R wave or R/S ratio > 1

Answer 67

A

Recent studies have shown that the most sensitive lead for detection of myocardial ischemia in patients who actually had an MI is lead V4 (sensitivity of 83%) but when two precordial leads are monitored simultaneously the sensitivity increases to 97%.

A separate study suggested that adding lead II with two precordial leads increases the sensitivity for detection of myocardial ischemia to 98%.

Answer 68

A

Patients with massive burns demonstrate resistance to NDNMBs, resulting in increased dosing requirements, due to upregulation of ACh receptors and increased plasma protein binding.

Contraindicated = Succinylcholine

Mivacurium’s dosing requirements are only slightly increased relative to other NDNMBs as it is metabolized by pseudocholinesterase, the levels of which are decreased in burn patients.

Answer 69

A

Since NDNMB’s drug effect is produced by competitively inhibiting ACh receptors, the presence of more receptors means a higher dose of free drug is required to produce neuromuscular blockade manifesting as twitch depression.

Burn patients also have increased protein binding, meaning less free drugs are available to bind ACh receptors, further increasing dose requirements.

Answer 70

A

The durations of action of commonly-used anticholinesterases and anticholinergic drugs for reversal of nondepolarizing neuromuscular blockade are prolonged in the setting of CKD and ESRD.

However, no dosage alterations are required and the normal maximum recommended doses still apply.

Answer 71

A

Increasing the dose of anticholinesterase relative to anticholinergic drug:

Increases the risk for gastrointestinal upset
Nausea/vomiting
Cardiac muscarinic effects including significant bradycardia or other arrhythmias.

Answer 72

A

Increasing the dose of anticholinergic relative to anticholinesterase:

Increases the risk for tachycardia and other arrhythmias
Blurred vision
Dry mouth

Confusion or hallucination may be seen with anticholinergics that cross the blood-brain barrier (e.g. atropine).

Answer 73

A

The risk for prolonged QT intervals is greatest in patients taking greater than 120 mg daily, however, lower doses and acute use can still prolong the QT interval.

Because methadone is metabolized by cytochrome p450, drugs inhibiting this enzyme may lead to increased methadone toxicity and further QT prolongation.

Answer 74

A

It causes dose-dependent inhibition of adrenal mitochondrial 11β-hydroxylase.

The enzyme 11β-hydroxylase is responsible for the conversion of 11-deoxycortisol to cortisol.

Thus, administration of etomidate causes suppression of adrenal cortisol synthesis.

Answer 75

A

Pulmonary vascular resistance is affected by lung volumes.

It is lowest at FRC while increasing or decreasing lung volumes beyond FRC results in an increase in PVR.

Highest at Residual Volume and Total Lung Capacity

Pulmonary vascular resistance increases as lung volumes increase due to compression of the smaller pulmonary vessels, notably the small arterioles. As lung volumes increase, alveoli expand and the transmural (distending) pressure in and radii of the small blood vessels decrease. Therefore, PVR increases. Recall that resistance (R) is inversely proportional to vessel radius (r) to the fourth power (R ∝ 1/r4).

Answer 76

A

First, as the size of the alveoli decrease and especially when they collapse, the geometry of the pulmonary vessels surrounding these alveoli changes such that the vessels can essentially become kinked, resulting in a significant increase in resistance to flow.

Second, as lung volumes decrease below normal, the volume of blood in the larger pulmonary vessels decreases. This suggests a likely decrease in vessel radius and therefore increased resistance to flow.

Answer 77

A

Hyperosmolality (milliosmoles per kilogram. A normal result is typically 275 to 295 milliosmoles per kilogram)
Reduced Effective Circulatory Volume

Answer 78

A

Water Balance:

Stimulates water reabsorption by increasing intracellular levels of cyclic adenosine monophosphate (cAMP) and activating protein kinase A

Vasoactive

Vasoconstriction by activating G protein and phospholipase C, which releases calcium from the sarcoplasmic reticulum. There are two classes of AVP receptors:

V1 receptors present in vascular smooth muscle

V2 receptors present in the distal and collecting tubules of the kidney

Answer 79

A

Transtracheal injection of local anesthetic will block the recurrent laryngeal nerve

Answer 80

A

FFP is frozen for storage. It can be transfused up to 5 days after thawing

Factors VIII and V are the least stable factors in blood products and can degrade above 4 degreres Celcius.

Significant reductions in factor VIII (41 ±8%) and factor V (66 ±9%) levels.

Answer 81

A

Plasma clearance
Redistribution

Answer 82

A

Diastasis occurs when there is complete left ventricular relaxation and filling of the ventricle eventually slows down.

It occurs* during the *filling portion following isovolumetric relaxation.

Answer 83

A

Baricity of the local anesthetic solution

(Baricity refers to the density of a substance compared to the density of human cerebrospinal fluid)

Solutions that have a baricity approaching 1.000 are referred to as isobaric*, as the density of the cerebrospinal fluid is approximately 1.0003+/- 0.0003. Solutions with a baricity less than 0.999 are termed hypobaric, and are usually created by mixing the local anesthetic with distilled water. *Hyperbaric solutions are created by mixing dextrose 5-8% with the desired local anesthetic.

Hyperbaric solutions will flow in the direction of gravity and settle in the most dependent areas of the intrathecal space. Conversely, hypobaric mixtures will rise in relation to gravitational pull.

2. Patient position.

Answer 84

A

1. Atropine (Blocks parasympathetic activation)

2. Papaverine - opium alkaloid antispasmodic drug, used primarily in the treatment of visceral spasm and vasospasm (especially those involving the intestines, heart, or brain

3. Naloxone - (blocking opioid receptor activation)

Answer 85

A

Neck flexion - Risk of endobronchial intubation

Neck extension - Risk of ETT herniating out of the larynx.

Answer 86

A

*- Hypocalcemia
Hyperkalemia
Hypermagnesemia
Hyperlipidemia
Hyperphosphatemia**

Answer 87

A

Citrate Chelates both magnesium and calcium so you have:

Hypomagnesemia and Hypocalcemia

Answer 88

A

FFP and Platelets

(NOT PRBC)

Answer 89

A

Osmolarity (mOsm/L) 253

Sodium (mEq/L) None

Chloride (mEq/L) None

Potassium (mEq/L) None

Glucose (g/L) 50 grams / Liter

Lactate (mEq/L) None

Answer 90

A

Osmolarity (mOsm/L) 355

Sodium (mEq/L) 38.5

Chloride (mEq/L) 38.5

Potassium (mEq/L) None

Glucose (g/L) 50

Lactate (mEq/L) None

Answer 91

A

Osmolarity (mOsm/L) 308

Sodium (mEq/L) 154

Chloride (mEq/L) 154

Potassium (mEq/L) None

Glucose (g/L) None

Lactate (mEq/L) None

Answer 92

A

Osmolarity (mOsm/L) 432

Sodium (mEq/L) 77

Chloride (mEq/L) 77

Potassium (mEq/L) - None

Glucose (g/L) 50

Lactate (mEq/L) - None

Answer 93

A

Osmolarity (mOsm/L) 1026

Sodium (mEq/L) 513

Chloride (mEq/L) 513

Potassium (mEq/L) None

Glucose (g/L) None

Lactate (mEq/L) None

Answer 94

A

Osmolarity (mOsm/L) 273

Sodium (mEq/L) 130

Chloride (mEq/L) 109

Potassium (mEq/L) 4

Glucose (g/L) 0

Lactate (mEq/L) 28

Answer 95

A

Osmolarity (mOsm/L) 525

Sodium (mEq/L) 130

Chloride (mEq/L) 109

Potassium (mEq/L) 4

Glucose (g/L) 50

Lactate (mEq/L) 28

Answer 96

A

Osmolarity (mOsm/L) 294

Sodium (mEq/L) 140

Chloride (mEq/L) 98

Potassium (mEq/L) 5

Glucose (g/L) None

Lactate (mEq/L) None

Answer 97

A

Osmolarity (mOsm/L) 586

Sodium (mEq/L) 154

Chloride (mEq/L) 154

Potassium (mEq/L) None

Glucose (g/L) 50

Lactate (mEq/L) None

Answer 98

A

P1V1 = P2V2

“Water Boyle’s at a constant temperature”

Answer 99

A

V1/T1 = V2/T2

“Prince Charles is under constant pressure to be king”

Answer 100

A

P1 / T1 = P2 / T2

A Culdissac “LUSSAC” has a constant volume and mass of gas

Answer 101

A

C = kP

Henry’s law indicates that at a constant temperature, the concentration of a gas dissolved in a solution is directly proportional to the partial pressure of that gas: C = kP (where k is a solubility constant) or C ∝ P. As the volume percentage of a volatile anesthetic is increased, the alveolar partial pressure increases.

Example: An increased alveolar partial pressure, therefore, leads to an increased concentration of the volatile anesthetic in the blood which increases the speed of induction and depth of anesthesia.

Answer 102

A

P total =- P1 + P2 + P3

Dalton’s law (also called Dalton’s law of partial pressures) states that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases.

Answer 103

A

Though it vaporises very readily, it is a liquid at room temperature.

Desflurane vaporizers are typically heated to 39 °C which creates a constant desflurane vapor pressure of 2 atm within the vaporizer, independent of barometric pressure.

Answer 104

A

The maximum dose of neostigmine is 70-80 mcg/kg at which point a “ceiling effect” takes place.

This dose results in complete blockade of the acetylcholinesterase enzymes and occurs in approximately 10 minutes.

Answer 105

A

In some instances additional anticholinesterase medication may cause paradoxical weakening.

The anticholinesterase effect increases the amount of acetylcholine release. In an overdose, depolarization of the endplate caused by the excess acetylcholine can lead to a depolarization block, similar to that seen with succinylcholine.

Answer 106

A

Renal Artery Stenosis
Pregnancy
History of angioedema (whether related to ACE-I or not).

Answer 107

A

Circuit Disconnect

Esophageal Intubation

Kinked ETT

Answer 108

A

Circuit Leak

Partial Airway Obstruction

Answer 109

A

Pulmonary embolism

Circulatory Collapse

Answer 110

A

1. Decreased Minute Ventilation

2. Faulty Unidirectional Valve

3. Soda Lime Exhaustion

4. Insufficient Fresh Gas Flow

5. Laparoscopes are inserted into the subcutaneous space causing ETCO2 in the skin (Subcutaneous emphysema)

6. Malignant Hyperthermia

7. Thyroid Storm

Answer 111

A

Keep IV catheter in place initially.
Aspirate about 5 mL of blood to remove as much of the drug as possible.

1. Limb elevation

2. Warm compresses (for vasopressors, cold compress for other drugs)

3. Irrigating with saline (Gault technique)

The Gault technique can be used to wash out the extravasated drug. It starts with injecting hyaluronidase (about 1500 units) into the subcutaneous tissue of the affected area. Four incisions are made at the site and saline (approx. 500 ml) is flushed through one of the incisions. This will irrigate the subcutaneous tissue and flow out the other three incisions.

Hyaluronidase is an enzyme that breaks down hyaluronic acid found in the tissue. This allows the subcutaneous tissue to become more permeable. It is typically used for vesicants, particularly in children (e.g., infant with extravasated parenteral nutrition)

4. Injection of phentolamine

Phentolamine causes the smooth muscles of blood vessels to relax and produces vasodilation. Recommended dose is 5-10 mg within 12 hours of the extravasation. Phentolamine is typically diluted to 0.5 mg/mL then injected in multiple locations, in 1 mL increments, around the border of the extravasation site.

5. Stellate ganglion block (for upper limbs).

In situations with extravasated vasopressors, a stellate ganglion block will create a sympathectomy causing vasodilation in the upper limb.

Answer 112

A

Mild extravasation can lead to local necrosis and more severe extravasations may require open surgical debridement/fasciotomies. (Definitive treatment)

Extravasated vasoconstrictors usually have a 4-6 hour window before the onset of tissue necrosis.

Chemotherapeutic drugs have about 72 hours before necrosis begins.

Answer 113

A

Accidental intra-arterial injection of drugs can cause vasospasm and thrombosis.

Management includes injecting:

1. lidocaine

2. calcium channel blocker intra-arterially

3. A stellate ganglion block can also be useful.

Answer 114

A

Acetylsalicylic acid (ASA) blocks It is non-selective for COX-1 and COX-2 enzymes

Inhibition of COX-1 results in:

the inhibition of platelet aggregation for about 7-10 days (average platelet lifespan)
This prevents the production of pain-causing prostaglandins
Stops the conversion of arachidonic acid to thromboxane A2 (TXA2), which is a potent inducer of platelet aggregation

Answer 115

A

Antiplatelet

Blocks GP IIb/IIIa receptors

Answer 116

A

Antiplatelet

Lowers calcium by elevating cAMP

Answer 117

A

Anti-platelet

Inhibit ADP Receptor activation

Answer 118

A

Anti-platelet

Lowers calcium by activating cAMP

Answer 119

A

Anti-platelet

Blocks GP2b3a receptors

Answer 120

A

Antiplatelet

Inhibit ADP Receptor Activation

Answer 121

A

Anti-platelet

Inhibit ADP Receptor Activation

Answer 122

A

Anti-platelet

GP2b3a receptor inhibitor

Answer 123

A

Anticoagulant

Direct Factor Xa Inhibition

Answer 124

A

Anti-coagulant

Direct Factor Xa Inhibition

Answer 125

A

Anticoagulant

Antithrombin mediated inhibition of factor Xa

Answer 126

A

Anti-coagulant

Antithrombin mediated inhibition of serine proteinases

LMWH binds to anti-thrombin, a serine protease inhibitor, and creates a conformational change. This change accelerates its inhibition of activated factor X in conversion of prothrombin to thrombin. Thus,thrombin cannot convert fibrinogen to fibrin strands and clot formation.

Once this change occurs LMWH is freed and can bind to another anti-thrombin molecules. LMWH also directly inhibits thrombin as it is a heterogenous mixture of molecules, some containing enough polysaccharide sequence, but this effect is much less than that of unfractionated heparin.

Answer 127

A

Anticoagulant

Direct factor Xa inhibition

Answer 128

A

Anticoaglant

Antithrombin mediated inhibition of serine proteinases

Answer 129

A

Anti-coagulant

Inhibit vitamin K dependent coagulation factors (II, VII, IX, X)

Answer 130

A

The NMDA receptor is an inotropic glutamate receptor that functions as a nonspecific ion channel when activated. Activation only occurs when glutamate is bound to the receptor AND the cell is depolarized. The receptor’s effects are primarily mediated via increased intracellular calcium.

Answer 131

A

Administration of magnesium along with ketamine can potentiate the effects of ketamine.

Answer 132

A

1. Electrode Gel

2. Applying Force (if paddles)

11 lbs of pressure reduces resistance

3. Biphasic Defibrillation

Uses less energy

4. Larger Electrodes (8-12 cm)

Paddle size is inversely proportional to transthoracic resistance
Smaller pads can cause myocardial necrosis

Answer 133

A

6 P’s

Pain out of proportion to the injury

Paresthesias

Pain on passive movement

Palpation of a tense hard compartment

Paralysis

Pulselessness (Late sign)

Diagnosis: Compartment Pressures >30 mmHg needs a fasciotomy within 6 hours

Answer 134

A

(Hgb * {4/3} * SaO2) + (0.003 * PaO2)

Answer 135

A

Only the posterior arytenoids and the epiglottis are visible

Answer 136

A

Peak Expiratory Pressure will decrease the most

In healthy patients, lumbar or low thoracic epidural anesthesia produces small (≤ 10%) changes in most pulmonary function parameters. However, PEP and cough strength are significantly reduced (10-40% and up to 50%, respectively) from baseline.

These two parameters are more dependent on abdominal musculature which has a higher degree of motor blockade than thoracic musculature from a lumbar or low thoracic epidural.

Note a disproportionately greater decrease in peak expiratory pressure with only a small decrease in FEV1 is in line with FEV1 being relatively effort-independent (lower peak expiratory pressure in a weaker patient is conceptually equivalent to lower effort).

Answer 137

A

Tidal volume is typically unchanged, even with a high thoracic epidural.

Answer 138

A

MAC-Awake

The MAC-awake is the MAC value at which voluntary reflexes (e.g., a patient will no longer open his or her eyes to command, shouting, or shaking) and perceptive awareness are lost. It varies between 15-50% of standard MAC

MAC

minimum alveolar concentration of an inhaled anesthetic at one atmosphere that prevents movement in response to a surgical stimulus (specifically, an abdominal incision) in 50% of patients.

MAC-BAR

MAC value at which the adrenergic response (e.g., hemodynamic, sudomotor) to noxious stimuli is blunted. This has been found to be approximately 50% higher than standard MAC. Some studies estimate this value as 1.7-2.0 MAC.

Answer 139

A

Interestingly, the MAC-awake is generally higher at induction (40-50% standard MAC in order for loss of consciousness) than at emergence (as low as 15% standard MAC to regain consciousness)

Although the mechanism is not fully understood, it is likely due to the differences in alveolar wash-in and wash-out of anesthetic gases.

The theory of neural inertia is another proposed mechanism.

Neural inertia is defined as the tendency of the central nervous system to resist transitions between arousal states

Answer 140

A

The loss of awareness and recall typically occurs at 0.4-0.5 standard MAC

Isoflurane likely has the most recall-blocking activity and nitrous oxide the least

Answer 141

A

Current ASA guidelines recommend maintaining at least 0.7 MAC during general anesthesia to significantly reduce the risk of awareness.

A MAC value of 0.627 effectively reduces awareness to 1 in 100,000 for recall of verbal stimulus.

Answer 142

A

Even a single episode of hypotension decreases cerebral perfusion enough to affect outcomes. The CPP value to target lies within the range of 50-70 mm Hg according to current BTF (Brain Trauma Foundation) guidelines.

Avoid CPP < 50 mmHg

As far as the upper limit, aggressive attempts to maintain CPP > 70 mmHg with fluids and pressors should be avoided because of the risk of acute respiratory distress syndrome (ARDS). However, if a patient with intact autoregulation is maintaining a CPP > 70 mmHg spontaneously, that is acceptable.

Answer 143

A

TBIs are categorized by level of severity: mild, moderate, and severe.

A mild TBI is associated with a Glasgow Coma Scale (GCS) score of 13-15 and minimal to no loss of consciousness.

A moderate TBI is associated with a GCS of 9-12 and a loss of consciousness of 30 minutes or more.

A severe TBI is associated with a GCS of 3-8.

Answer 144

A

Treatment should be initiated with ICP thresholds above 20 mmHg.

Answer 145

A

Methadone also needs little adjustment in patients with renal disease.

Answer 146

A

Buildup of renally-excreted hydromorphone-3-glucuronide can lead to neuroexcitatory effects including agitation, restlessness, and myoclonus (neuroexcitatory & pro-convulsant properties)

Answer 147

A

Prevents the synthesis of prostaglandins.

Inhibition of PG synthesis can affect renal glomerular blood flow by causing vasoconstriction of the afferent arterioles of the glomeruli

(KIDNEY ISSUES)

Reversibly inhibits the cyclooxygenase (COX) enzyme which prevents the formation of thromboxane from arachidonic acid.

Thromboxane promotes platelet aggregation and its absence can lead to increased bleeding.

(BLEEDING AND THROMBOSIS ISSUES)

Answer 148

A

Lead V1 is the second-best lead for monitoring atrial arrhythmia and when using a full twelve lead ECG considering these two leads together is most effective.

The normal p-wave morphology in V1 is biphasic with an initial upward deflection as depolarization travels from the SA node anteriorly through the right atrium. There is then a terminal deflection as the current passes posteriorly through the left atrium.

Answer 149

A

#1 = Fluid Hydration

Antioxidants such as N-acetylcysteine and ascorbic acid may also play a role in renal protection but are not as effective as fluid hydration alone.

Answer 150

A

SVR = [80 * (MAP – RAP)] ÷ CO

MAP = mean arterial pressure (mm Hg)
RAP = right atrial pressure (mm Hg), central venous pressure is commonly substituted for RAP
CO = cardiac output (L/min)
80 = conversion factor which changes mm Hg/L/min (Woods unit) to dynes * sec/cm^5

Answer 151

A

PVR = [80 * (MPAP – PAOP)] ÷ CO

*MPAP** = mean pulmonary arterial pressure (mm Hg)
*PAOP** = pulmonary artery occlusion pressure or pulmonary capillary wedge pressure (mm Hg)
*CO** = cardiac output (L/min)
*80** = conversion factor which changes mm Hg/L/min (Woods unit) to dynes * sec/cm^5

Normal Value = 20–130

Answer 152

A

Conversion of dynes * sec/cm^5 to Woods units may be achieved by dividing SVR by 80.

For example, 1520 / 80 = 19 Woods units

Answer 153

A

1. Thrombosis (Vascular > Infection)

2. Bleeding

3. Pseudoaneurysms

4. Arterial-Venous Fistula

5. Infection (Lower Risk)

6. Median Nerve Injury

There have been concerns that brachial artery catheterization can lead to limb ischemia due to lack of collateral vessels; however, this has not been shown to be true.

The rare instances of ischemia from brachial artery use were resolved with the catheter removal.

The radial artery is even more unlikely to have ischemia because of multiple collateral vessels.

Answer 154

A

ED95 is the effective dose of a neuromuscular blocking drug required to achieve 95% block of a single twitch in 50% of individuals who receive this drug and dose.

Answer 155

A

NDNMB ED95 (mg/kg)

Dose For Intubation (mg/kg)

Cisatracurium

04 (0.032 - 0.05)
15-0.2 (3.75 - 5 x ED95)

Pancuronium

07
08-0.12 (1.2 - 1.8 x ED95)

Rocuronium

3
6-1.0 (2 - 3.3 x ED95)

Vecuronium

05
1-0.2 (2.3 - 4.7 x ED95)

Answer 156

A

The term P50 is designated as the partial pressure of oxygen (in mm Hg) when oxygen saturation (SaO2) is 50%.

In a normal adult, P50 is 27 mm Hg.

Answer 157

A

Left Shift
In newborns, oxygen affinity is very high and P50 is very low (approximately 18 mm Hg).

Due to:

Hemoglobin F, which is produced in-utero, and is useful for oxygen transfer from the maternal blood to the fetus. The presence of hemoglobin F
Low 2,3-diphosphoglycerate (2,3-DPG) levels in newborns result in a very low P50 (Note, this would cause a left shift as well)

Answer 158

A

Right Shift

After birth, levels of hemoglobin F begin to decline (Right shift) resulting in a decrease in the total hemoglobin concentration. This results in a physiological anemia of infancy. During this same period of time, 2,3-DPG levels begin to increase causing the oxyhemoglobin dissociation curve to shift to the right (P50 increases). The P50 will surpass that of an adult (27 mm Hg) and will reach a maximum of 30 mm Hg by about 12 months of age

- Children will continue to have a higher P50 for the first decade of life.

Answer 159

A

P50 increases due to: acidosis, hypercarbia, hyperthermia, increased 2,3-DPG. Shift “RIGHT”:

Rise In 2,3-DPG, H+, and Temp.

P50 decreases due to: alkalosis, hypocarbia, hypothermia, decreased 2,3-DPG.

Answer 160

A

Age 10

Answer 161

A

Illustrates that the oxygenation of hemoglobin lowers the affinity of hemoglobin for carbon dioxide

The Haldane effect describes the relationship between the carbon dioxide dissociation curve in blood and oxyhemoglobin (HbO2).

The CO2 dissociation curve, specifically, shifts to the right when the concentration of HbO2 increases in the blood.

This curve is linear since the CO2 content and the partial pressure of CO2 (PCO2) are directly correlated in a given sample of blood. The curve may be interpreted such that an increase in HbO2 results in an increased dissociation of CO2 from Hb (i.e., an increase in PCO2 but an overall unchanged value for CO2 content).

Conversely, if the concentration of HbO2 is reduced, then the affinity for carbon dioxide increases and less CO2 is available for gas exchange.

Answer 162

A

The Bohr effect describes the binding effect of H+ to Hb chains and the oxygen release and dissociation that occurs thereafter.

Acidosis, for example, will shift the oxygen-hemoglobin dissociation curve toward the right, resulting in less attraction between Hb and O2.

Ultimately, this will permit more CO2 to be transported from the tissue to the lungs during gas exchange. The curve will shift to the left for a low PCO2 and high pH.

Answer 163

A

Treatment: Withholding warfarin for several days is recommended.

The half-life of warfarin therapy is 2 to 4 days thus the effects may not be seen for several days.

Answer 164

A

Treatment: Vitamin K can be administered orally or parenterally

Typical adult dose is 1-2mg)
There is no difference in efficacy between oral and intravenous vitamin K
Higher risk of anaphylaxis with parenteral formulations; thus oral is preferred if the patient can tolerate and absorb the medication

Answer 165

A

Treatment: Higher doses of vitamin K may be attempted (between 5-10mg).

Higher doses of vitamin K may render the patient temporarily resistant to further warfarin therapy for days to weeks.

Answer 166

A

1. Prothrombin complex concentrates

2. IV Vitamin K

Answer 167

A

4-factor concentrates are preferred as they contain all vitamin K dependent coagulation factors (II, VII, IX, and X) (1972)

3-factor concentrates contain factors II, IX, and X and should be supplemented with recombinant factor VIIa to completely reverse anticoagulation.

Answer 168

A

Contraindications:

1. DIC

2. HIT - PCCs are human plasma derived products that contain low doses of heparin to prevent clotting factor activation.

Answer 169

A

There are certainly risks associated with FFP transfusion; most notable are:

Transfusion related acute lung injury (TRALI)

Febrile reactions

Allergic reactions

Transfusion associated circulatory overload (TACO).

Answer 170

A

Minimal Sedation

Moderate Sedation

Deep Sedation

General Anesthesia

Answer 171

A

Responsiveness
Airway reflexes
Ventilation
Cardiovascular Function

*Minimal Sedation**
Normal response to verbal stimulation
Airway reflexes, spontaneous ventilation, and cardiovascular function are all unaffected
*Moderate Sedation**
Purposeful response to verbal or tactile stimulation
Spontaneous ventilation is adequate and no airway intervention is required
Cardiovascular function is usually maintained
*Deep Sedation**
Purposeful response to repeated or painful stimulation (reflex withdrawal from a painful stimulus is NOT considered purposeful response)
Spontaneous ventilation may be inadequate and airway intervention may be required
Cardiovascular function is usually maintained
*General Anesthesia**
Unable to arouse even with painful stimulus
Spontaneous ventilation is frequently inadequate and airway intervention is often required
Cardiovascular function may be impaired

Answer 172

A

A = Diuretics

B = Ionotropes + Vasodilators + Diuretics

C = Vasodilators

D = Ionotropes and Vasodilators

E = Ionotropes only

Answer 173

A

50% renal excretion

Answer 174

A

Without = 77 minutes

With = 181 minutes

Answer 175

A

46 - 73 minutes

Answer 176

A

Metabolism = 70% Hepatic

Elimination = 10% Renal Elimination

Answer 177

A

Metabolism - 50-60% Hepatic

Elimination - 25% Renal

Answer 178

A

Triggered when the pressure in the breathing circuit falls below atmospheric pressure by a predetermined amount (typically below -10 cm H2O).

Examples

Inhalation against an increased resistance in the circuit
Inhalation against a collapsed reservoir bag
A malfunctioning active closed scavenging system (excessive vacuum or valve dysfunction)
A blocked inspiratory limb during exhalation
Accidental Placement of Nasogastric Tube or Endoscope within the trachea and use of suction = Loss of Tidal Volume and Negative pressure

Answer 179

A

Myoclonus describes sudden jerking movements, such as those sometimes observed during induction of anesthesia

It likely results from inhibition of descending cortical inhibitory pathways.

Myoclonus can resemble seizures but EEG evidence of seizures is lacking during these episodes.

Answer 180

A

1. Myoclonus

2. Pain on Injection

3. Hiccups

Answer 181

A

Dopamine-1 agonist = Increases renal blood flow despite decreased systemic arterial blood pressure

Natriuretic - Sodium excretion

Diuretic - Free water excretion

Direct renal vasodilator and can produce hypotension

Answer 182

A

A dopamine D1 receptor agonist that is used as an antihypertensive agent
It lowers blood pressure through arteriolar vasodilation.
Used as renal protector when renal vasoconstriction is anticipated
Hypertensive Crisis in those with decreased renal function

Answer 183

A

Acute phenytoin administration potentiates the neuromuscular blockade of aminosteroid NDNBDs.

Chronic phenytoin administration increases a patient’s resistance to the effects of NDNBDs and reduces their duration of action by as much as 50%

For benzylisoquinoloine NMB = Variable

Answer 184

A

1) Increased metabolism via cytochrome P450 enzymes induction (this may explain why there is a clear effect with the aminosteroid NDNBDs, which rely on hepatic metabolism, but not with the benzylisoquinolines which undergo hepatic-independent Hofmann elimination and ester hydrolysis)
2) Increased postjunctional acetylcholine receptor density (the weak neuromuscular blocking properties of phenytoin, see below, results in postjunctional acetylcholine receptor upregulation)
3) Decreased sensitivity at the receptor sites
4) Increased end-plate anticholinesterase activity

Answer 185

A

ETT placement (MOST)

Surgical INcision

DL

Tetanus by nerve stimulation (LEAST)

Answer 186

A

Partial Opioid Agonist and Mixed Agonist-Antagonist

Answer 187

A

0 - 8 mmHg

Answer 188

A

10 - 18 mmHg

Answer 189

A

25 mmhg

Answer 190

A

2.5 - 4.2

Answer 191

A

*Raises** Intrathoracic Pressure
*Increase** in RV Afterload

Decrease in Preload

Increase in CVP

Increase in PAP

Improved CI

Improved PCWP

Answer 192

A

Consciousness

Activity (Moving extremities on command)

Respiration

Oxygen Saturation with O2 requirements

Circulation (BP compared to preop)

Answer 193

A

Right to Left Shunt

Answer 194

A

Elevated Anion Gap Metabolic Acidosis

Cyanide primarily causes toxicity by impairing cellular aerobic respiration. The cyanide ion (CN-) binds to the ferric ion (Fe3+) in mitochondrial cytochrome-c oxidase, inhibiting the final stage of the electron transport chain. Depletion of cellular ATP and the lactic acid produced by anaerobic metabolism can lead to profound acidosis.

Answer 195

A

Signs/Symptoms:

Altered mental status, weakness, headaches, loss of consciousness, seizures, respiratory failure, and cardiac arrest, The patients blood sample may appear “cherry red” due to normal circulating levels of oxygen with impaired utilization.

PaO2 increases (Oxygen present but cannot be utilized)

SvO2 increased (oxygen present but not being utilized)

Answer 196

A

A = Minute Ventilation

B = 2-3 times minute ventilation

C = 1-2 times minute ventilation

Answer 197

A

LFT’s

Liver Dysfunction and potentially liver failure is possible

Answer 198

A

Radiation intensity (exposure) with respect to distance decreases according to the inverse square law: I ∝ 1 / r^2.

Accordingly, doubling the distance from a radiation source decreases exposure by a factor of 4.

Answer 199

A

Hypotension

Hypocalcemia (Transiently binds calcium and should be cautious in hypocalcemic patients)

Answer 200

A

Hypercarbia - The reaction of 50 mEq bicarbonate produces approximately 1,250 mL of CO2 which must be exhaled and is seen as a transient increase in EtCO2.

Answer 201

A

Redistribution of Blood to the Pulmonary Vasculature

Answer 202

A

Simply, CN 9 and CN 10

Specifically:
1. Internal Branch of Superior Laryngeal Nerve of CN 10

CN 9 - Glossopharyngeal Nerve
Recurrent Laryngeal Nerve of CN 10

Answer 203

A

Arteriodilation - Due to sympathectomy

Reduction in afterload

2. Venodilation - Due to sympathectomy

Venodilation causes a reduction in preload and tends to have a more dramatic effect than arterial dilation because 75% of the total blood volume is in the venous system.

Bradycardia - 10-15% from the spinal
Blockade of the cardiac accelerator fibers can prevent an increased heart rate in response to hypotension, which would lead to further hypotension and bradycardia.

Answer 204

A

Parasympathetic-mediated reflex occurs when stretch receptors located mainly in LV respond to an acute decrease in LV preload

The result is bradycardia and reduced contractility (and resultant hypotension).

This reflex is thought to occur to allow the ventricle additional time to fill and increase preload.

Answer 205

A

2-6 Dermatomes sensory block above level of the sensory block

Answer 206

A

Quantitative echocardiographic technique used to determine left ventricular ejection fraction.

Answer 207

A

Jet Velocity - (3-4 m/s)
Mean Gradient - (25 - 40 m/s)
Valve Area (1.0 - 1.5)

Answer 208

A

>20 degrees

Answer 209

A

≥1 MAC increase CBF and decrease CMRO2, causing an uncoupling of the flow-metabolism relationship.

<1 MAC = CBF balances and remains the same

Answer 210

A

The cerebral flow-metabolism relationship and cerebral autoregulation remain intact with the use of thiopental.

Thiopental decreases both CBF and CMRO2 by 30% with induction doses

and by 50% upon achievement of an isoelectric EEG.

Answer 211

A

Burst suppression on EEG is the goal target of reducing CMRO2 during an open cerebral aneurysm clipping.

Burst suppression sufficiently indicates depressed CMRO2 while providing predictability of recovery and awakening once the IV anesthetic is turned off.

Answer 212

A

Elevated Mixed Venous Oxygen (PvO2)

Since cells cannot use oxygen and aerobic respiration, PVO2 becomes elevated.

SNP (Sodium Nitroprusside) Tachyphylaxis
Metabolic Acidosis (Lactate Buildup)

Answer 213

A

Amyl nitrate works as an antidote for cyanide poisoning by converting Hb to MetHb which avidly binds cyanide, converting it to the nontoxic cyanomethemoglobin.

Answer 214

A

Hydroxycobalamine
Amyl NItrate
Sodium Thiosulfate

Answer 215

A

Cimetidine 1-1.5 hours, 3-4 hours

Ranitidine 1 hour, 9-10 hours

Famotidine 1 hour, 10-12 hours

Answer 216

A

Histamine H2 receptor antagonists (e.g. cimetidine, ranitidine, famotidine, nizatidine) block histamine from inducing acidic gastric fluid secretion by parietal cells.

This effectively raises gastric pH.

Raising the gastric pH prior to induction of anesthesia can reduce the severity and risk of perioperative aspiration pneumonitis.

Answer 217

A

Barium hydroxide absorbent preparations produce more carbon monoxide than soda lime due to the decreased water content of barium hydroxide absorbents.

Answer 218

A

Soda Lime

Answer 219

A

80% calcium hydroxide

15% water

4% sodium hydroxide

Therefore, higher-moisture absorbents (e.g., soda lime) have more water content available to react with CO2 leading to an increased CO2 absorptive capacity.

Answer 220

A

Desiccated CO2 absorbents

Increased Temperature

Low Fresh Gas Flows

Answer 221

A

CO2 absorbents + Sevoflurane = Most Heat

CO2 absorbents + Desflurane = Most CO

Answer 222

A

Barium Hydroxide

*These have been removed from US markets

Answer 223

A

Lack Strong Bases (NaOH and KOH)

The maximum CO2 absorbed by calcium hydroxide is 10.2 liters per 100 grams absorbent whereas soda lime can absorb 26 liters of CO2 per 100 grams absorbent.

Answer 224

A

Calcium hydroxide absorbents, due to lower reactivity, have the lowest incidence of compound A and fire production

Answer 225

A

If you suspect a colleague of having a substance abuse problem, you should consult your state physicians health program before intervention or confrontation.

Answer 226

A

Correction of excessive microvascular bleeding (PT >1.5 times normal, PTT >2 times normal, or INR >2)
Correction of coagulation factor deficiencies if the patient has been transfused with more than one blood volume (approximately 70 ml/kg)
Correction of coagulation factor deficiencies for which there are no specific replacements
Heparin resistance (antithrombin III deficiency) in a patient requiring heparin
Coagulopathy related to hepatic insufficiency
TTP
Reversal of Warfarin (PCC another option)

Answer 227

A

Thrombotic thrombocytopenic purpura (TTP) is a platelet destruction disorder.

The inherited type involves a deficiency of vWF-cleaving protease activity (ADAMTS13 deficiency).

Fresh frozen plasma is administered in order to replete the ADAMTS13 enzyme.

Plasmapheresis may be used to treat the acquired type of TTP as it removes the acquired antibodies that damage the ADAMTS13 enzyme.

Answer 228

A

Esmolol is a β1-selective short acting (t1/2 = 9 min) agent that is

Rapidly metabolized by:

Red blood cell (RBC) esterase
Minimally hydrolyzed by pseudocholinesterase.

Answer 229

A

Beta-blockers reduce:

1. blood pressure

2. myocardial oxygen consumption

primarily by

1. decreasing heart rate

2. contractility.

They also have anti-arrhythmic properties by decreasing AV conduction and automaticity, and by increasing the atrial refractory period.

Answer 230

A

Propranolol is non-selective and inhibits β1 and β2 receptors

Answer 231

A

β1, β2, and α-1 receptor blocker.

Answer 232

A

The ratio of relative α:β potency of IV labetalol is approximately 1:7 whereas PO labetalol is 1:3.

The nature of this drug can be seen intraoperatively when labetalol administration results in decreased blood pressure without baroreceptor-triggered reflex tachycardia (as can be seen with pure vasodilating agents)

Answer 233

A

Carvedilol

Answer 234

A

Hepatic Clearance

Exception: Atenolol (Which is renally cleared)

Answer 235

A

The pathophysiology of PRIS relates to propofol’s ability to impair cellular free fatty acid utilization and mitochondrial activity leading to inadequate aerobic metabolism and increased reliance on anaerobic metabolism.

Answer 236

A

Cardiac and skeletal muscle are particularly susceptible leading to muscle damage or necrosis that can cause cardiac failure and rhabdomyolysis.

lactic acidosis

hyperkalemia

renal failure

Hypertriglyceridemia

Hepatomegaly

Pancreatitis secondary to HLD

Answer 237

A

Green

Phenol excretion can cause this

Answer 238

A

All drop

Answer 239

A

It has been shown that with head rotation greater than 30 degrees that the left carotid artery and jugular vein overlap more than on the right.

Answer 240

A

1. Carotid embolization on the left poses a greater risk as the left cerebral hemisphere is dominant in the majority of the population. This is also one of the reasons why right-sided carotid massage is preferred over left-sided massage.

Another reason is that some investigations have found a greater cardioinhibitory effect on the right side.

Answer 241

A

Exert Pressure on Carotid Sinus and baroreceptors at the Transverse process of C6

The AFFERENT nerve impulses of carotid sinus baroreceptors are transmitted by the Hering’s nerves to the glossopharyngeal nerve (CN IX) (see image below).

Arterial wall stretch at the carotid sinus, within the internal carotid artery, activates the afferent impulse.

This activation leads to stimulation of the nucleus tractus solitarius (NTS) in the caudal medulla.

The NTS sends excitatory signals to other regions of the medulla which in turn inhibit stimulation of the preganglionic intermediolateral nucleus of the spinal cord which mediates the body’s sympathetic innervation.

The NTS may also stimulate vagal nuclei to activate the parasympathetic nervous system via the vagus nerve. These two effects then lead to bradycardia and hypotension.

Answer 242

A

a wave: atrial contraction

Answer 243

A

c wave: TV bulging into RA during RV isovolumetric contraction

Answer 244

A

x descent: TV descends into RV with ventricular ejection and atrial relaxation

Answer 245

A

v wave: venous return to and systolic filling of the RA

Answer 246

A

y descent: atrial emptying into RV through open TV

Answer 247

A

absent a wave

Answer 248

A

Tall c waves

Tall v waves
Loss of x descent

Answer 249

A

Tall a

Tall v waves
Minimal y descent

Answer 250

A

Tall a & v waves
Steep x & y descent
M or W configuration

Answer 251

A

Tall a & v waves
Steep x & y descent
M or W configuration

Answer 252

A

Dominant x descent
Minimal y descent

Answer 253

A

Ascorbic Acid

Ascorbic acid also known as vitamin C, functions as an electron receptor and aids in the reduction of Fe3+ to Fe2+.

Ascorbic acid functions to reduce hemoglobin slower than methylene blue does. However, ascorbic acid does not have the hemolytic effect that methylene blue does in a G6PD deficient patient.

In a patient with G6PD deficiency the hexose phosphate pathway is dysfunctional and free radicals develop, which causes red blood cell lysis.

Answer 254

A

Methylene blue is often the drug of choice when treating methemoglobinemia.

Methylene blue provides an electron receptor for the reduction of methemoglobin using NADPH produced from the hexose phosphate pathway.

In a patient with G6PD deficiency the hexose phosphate pathway is dysfunctional and free radicals develop, which causes red blood cell lysis. Therefore, methylene blue should be avoided in patients with G6PD deficiency. Additionally, methylene blue is a potent reversible monoamine oxidase inhibitor (MAOI) and may interact with serotonergic psychiatric medications leading to life-threatening serotonin syndrome.

Answer 255

A

Additionally, methylene blue is a potent reversible monoamine oxidase inhibitor (MAOI) and may interact with serotonergic psychiatric medications leading to life-threatening serotonin syndrome.

Answer 256

A

Amyl nitrite is used to treat cyanide toxicity.

Amyl nitrate oxidizes Fe2+ to Fe3+.

Cyanide binds to methemoglobin more actively than it binds to normal hemoglobin.

Thus, by inducing a low-level of methemoglobinemia the methemoglobin in turn can sequester cyanide as cyanmethemoglobin.

Answer 257

A

Methemoglobinemia occurs when hemoglobin becomes oxidized from Fe2+ to Fe3+.

Methemoglobin is unable to bind oxygen and causes a functional anemia, in addition to left shifting the oxygen dissociation curve.

Methemoglobin has an absorbance of 630 nm, which correlates to an oxygen saturation of 84-86% on pulse oximetry.

Co-oximetry should be used to aid in the diagnosis and treatment of methemoglobinemia. If unavailable, blood can be sent for a methemoglobin level.

Answer 258

A

The COHb is interpreted by the pulse oximeter as a mixture of approximately 90% HbO2 and 10% HHb.

Thus, at high levels of COHb, the pulse oximeter will overestimate true SaO2, as may occur in patients with recent CO exposure.

Answer 259

A

MetHb is formed when the heme iron is oxidized from the ferrous (Fe2+) to the ferric (Fe3+) state.

metHb is very dark and tends to absorb equal amounts of red and infrared light, resulting in a red:infrared ratio of 1.

When extrapolated on the calibration curve, a ratio of 1 corresponds with a saturation of 85%.

Thus, as metHb increases, SpO2 approaches 85% regardless of the true level of HbO2.

Answer 260

A

Drugs capable of causing methemoglobinemia (defined as greater than 1% metHb) include nitrates, nitrites, chlorates, nitrobenzenes, antimalarial agents, amyl nitrate, nitroglycerin, sodium nitroprusside, and local anesthetic agents.

Answer 261

A

Injections of methylene blue produce a large and consistent spurious decrease in SpO2, with readings remaining below baseline for 1 to 2 minutes.

Injection of indocyanine green decreases SpO2 to approxi- mately 80% to 90%, which lasts for a minute or less.

Injection of indigo carmine decreases the SpO2 the least, with the decrease lasting approximately 30 seconds.

Answer 262

A

Botulism is caused by the anaerobic bacillus, Clostridium botulinum.

Flaccid neuroparalysis occurs due to the prevention of acetylcholine (ACh) release from vesicles at the NMJ.

Acetylcholine is carried to the nerve terminal by vesicles which then fuse with the nerve terminal membrane via soluble N-ethylmaleimide-sensitive fusion associated protein receptor (SNARE) proteins. The collection of SNARE proteins facilitate exocytosis and then “repackaging” or reuptake of ACh.

The various toxins of C. botulinum are zinc endopeptidases that cleave the SNARE proteins and stop the fusion and release of ACh into the nerve terminal, as well as prevent reuptake back into the terminal.

Answer 263

A

The tetanus toxin from Clostridium tetani travels via neuronal retrograde transport up the motor neuron and enters the presynaptic terminal of inhibitory interneurons within the spinal cord. Normal modulation of fine motor movement from descending motor pathways triggers the interneurons to exert their inhibitory effects via γ-aminobutyric acid (GABA) release.

The toxin prevents the release of GABA from the interneurons. Therefore, the inhibitory mechanism is inhibited and spastic neuroparalysis occurs.

Answer 264

A

1. Sternum

2. Proximal Humerus

3. Proximal Tibia

4. Distal Tibia

Answer 265

A

Sternum = Azygos and Internal Mammary Vein
Proximal Humerus = Axillary Vein
Proximal Tibia = Popliteal Vein
Distal Tibia = Greater Saphenous Vein

Answer 266

A

Humeral = Flow rates are higher than tibial (200 vs. 100 mL/min)

Sternal = Fast uptake of drugs (80-110 seconds) which is not that much longer than central access (60-80 seconds)

Answer 267

A

pKa = 6.5

Highly un-ionized form (90%)

Lower Lipid Solubility

Answer 268

A

Remembering “4” will get you in the appropriate range for differences between alfentanil and fentanyl.

Alfentanil has about 4 times faster onset.
Alfentanil lasts about 1/4 the duration.
Alfentanil is about 1/4 the potency (4x the dose of fentanyl).

Answer 269

A

Desflurane primarily decreases arterial pressure by decreasing afterload.

Desflurane increases heart rate, particularly when the concentration is quickly increased

Also causes dose-dependent depression of myocardial function.

Cardiac output is maintained and there is no significant effect on left ventricular diastolic function.

Answer 270

A

Acute dystonias (abnormal movement or posturing due to involuntary/sustained muscle contractions)
Akathisia (restlessness and need to be in constant motion)
Tardive dyskinesia (involuntary repetitive or purposeless movements).

Answer 271

A

Metoclopramide has weak antiemetic effect at 10 mg (< 20 mg) and recommended dosing for PONV is 25-50 mg IV.

EPS occur in 0.3% with 10 mg and 0.6% with both 25 mg and 50 mg dosing. Marginal increase in risk of EPS to cover PONV

Answer 272

A

Anticholinergics
- Benedryl 12.5 - 50 mg IV
- Benztropine

Initial dose: IM, IV, Oral: 1 to 2 mg once.

Subsequent doses: Oral: 1 to 2 mg 1 to 2 times daily.

3-8 all per True Learn but couldn’t find doses

Trihyexyphenidyl
Atropine
Anti-histamines
Benzodiazepines
Beta-Blockers
Dopamine Receptor Agonist

Answer 273

A

Antihistamine (H1)

Anticholinergic activity

Inhibits serotonin reuptake

Potentiates opioid-induced analgesia

May have Local anesthetic-like properties (intracellular sodium channel blocker).

Answer 274

A

Although nitrous oxide administration can worsen a venous air embolism, the risk is not increased significantly in intestinal surgery.

When the risk of venous air embolism is high, such as with sitting position neurosurgery, nitrous oxide should be avoided as it can increase the size of an air embolism should it occur.

Answer 275

A

1. Tension pneumothorax

Expansion of a pneumothorax is the most rapidly occurring of those listed, with volume doubling occurring in only 10 minutes

Expansion of venous air emboli

Worsening of pneumocephalus

Intestinal Obstruction

100cc of gas normally

Expansion could lead to: Not closing, ischemia from lumen obstruction,

Gas-filled spaces = bowel.

One of the concerns with Bowel Distention sx cannot proceed

Blindness

Answer 276

A

Chronic opioid therapy has a profound effect on the adrenal and gonadal axes leading to:

increased prolactin levels (Galactorrhea)

Decreased testosterone, estrogen, cortisol, LH, and FSH.

Answer 277

A

Pre-renal

BUN:creatinine ratio >20

FENa <1%

Urine Sodium (UNa) <10 mEq/Liter

Urine Osmolality (UOsm) >500 mOsm/kg

What are these values?

Answer 278

A

Intrinsic
BUN:creatinine ratio <15

FENa >2%

Urine Sodium (UNa) >20 mEq/Liter

Urine Osmolality (UOsm) <350 mOsm/kg

Answer 279

A

Post-Renal
BUN:creatinine ratio >15

FENa >4%

Urine Sodium (UNa) >40 mEq/Liter

Urine Osmolality (UOsm) <350 mOsm/kg

Answer 280

A

FENa = Excreted Na/Filtered Na x 100

(UNa x PCr) / (UCr x PNa x 100)
UNa – urine sodium
PNa – plasma sodium
UCr – urine creatinine
PCr – plasma creatinine

Answer 281

A

Propofol increases the time that the GABA-A receptors remain open after activation.

GABAA receptors, when active, allow Cl- to enter neurons and hyperpolarize the cell.

Hyperpolarization thus causes increased neuronal inhibition and unconsciousness

Answer 282

A

In some instances a bolus of dexmedetomidine can cause hypertension because of activation of the sympathetic nervous system.

Answer 283

A

Alpha2 receptors are prejunctional receptors activated by norepinephrine (negative feedback loop).

Answer 284

A

Chloride

Agonist = Alcohol
Antagonist = Caffeine

Answer 285

A

1. PCP

2. Nitrous Oxide

3. Methadone

4. Tramadol

Answer 286

A

However, a second dose of succinylcholine, if given within approximately five minutes of the first dose, increases the risk of bradycardia.

It is thought that the hydrolytic byproducts of succinylcholine metabolism (succinylmonocholine and choline) sensitize the myocardium to the parasympathetic effects of a second dose of succinylcholine, thus leading to bradycardia.

Answer 287

A

1. Drain CSF

2. Decrease parenchymal volume

Diuretics

Steroids

3. Decrease Cerebral Blood Flow

Adjust your PaCO2 with ventilation adjustment

Answer 288

A

CBF is directly related to PaCO2, and decreasing a patients PaCO2 via hyperventilation is one of the most widely used methods of decreasing CBF and therefore ICP.

CBF changes 1 to 2 mL/100 g/min with each millimeter of mercury change in PaCO2.

Below a PaCO2 of 25 mm Hg, CBF change is attenuated because severe vasoconstriction can cause local ischemia.

Therefore care must be taken when utilizing hyperventilation as a strategy to decrease ICP as ischemia can be an unwanted consequence.

Answer 289

A

Ions do not readily cross the blood brain barrier, but CO2 does.

For this reason, acute changes in PaCO2 affect CBF, but changes in blood HCO3- levels have no effect.

However, after 24-48 hours, the CSF HCO3- levels have adjusted to the change, and the CBF returns to normal.

Answer 290

A

W/ seizure history or epilepsy can trigger a new-onset seizure.

W/O seizure history or epilepsy, methohexital has not been known to trigger a seizures

Answer 291

A

Low Dose

Venous constriction results in improved preload from venous return and may improve cardiac output.

This is not seen in patients who have systolic heart failure, as the increased afterload can worsen cardiac output.

Notice VENOCONSTRICTION > arterial constriction

At high dose

Arterial & venous constriction → leads to decreased splanchnic perfusion

In higher doses, CO is commonly reduced due to increases in myocardial work and afterload.

The reduced splanchnic perfusion is more a result of arterial constriction than a reduction in cardiac output.

Answer 292

A

(LMWH) more selectively inhibits activated factor X when compared to unfractionated heparin (UFH)

A longer polysaccharide chain (higher molecular weight) is required for the increased binding sites leading to thrombin inhibition.

The shorter polysaccharide chains (lower molecular weight) of LMWH is more restricted in binding solely to ATIII, therefore more selectively inhibits Xa.

Benefit =

1. Selective Xa inhibition can be desirable as factor Xa has limited function outside the coagulation system, unlike thrombin which also plays a role in the immune system and inflammatory pathways.

2. Less HIT

Answer 293

A

Helium has an extremely low density and thus has an increased tendency for laminar flow.

Helium reduces airway resistance in large and medium airways (reduced resistance in turbulent flow). It can be used to decrease the work of breathing in pathologic conditions.

Answer 294

A

Incidence of post spinal backache = 11-13% of patients

Treatment:

Self-Limiting (Resolves in 7 days)

Mild analgesics such as acetaminophen, topical NSAIDs and patient reassurance.

Answer 295

A

Peripheral baroreceptors are located in both the:

Common carotid arteries

Aortic arch

Answer 296

A

When blood pressure is elevated, an increase in the baroreceptor firing in these areas causes an increase in the vagal tone (known as the baroreceptor reflex). (Stretch reflex)

In converse, decreases in blood pressure cause an inhibition of baroreceptor discharge resulting in decreased vagal tone.

Answer 297

A

Infective endocarditis prophylaxis is recommended for cardiac conditions listed below PLUS:

1) Dental (mucosal, gingival) procedures or
2) Respiratory tract (tonsillectomy, adenoidectomy, bronchoscopy with incision/biopsy) procedures or
3) Infected skin/musculoskeletal tissue procedures*
*High risk cardiac conditions:**
1) Prosthetic cardiac valve or prosthetic material used in valve repair
2) Previous endocarditis
3) CHD only in the following categories:
Unrepaired cyanotic congenital heart disease
Completely repaired congenital heart disease with prosthetic material or device within six months
Repaired congenital heart disease with residual defects
4) Cardiac transplantation recipients with cardiac valvular disease

Answer 298

A

Type A - alpha (Fastest), beta, gamma, delta

Type B

Type C - Dorsal Root and Sympathetic (Slowest)

Answer 299

A

Alpha = Propiroception , Motor

Beta = Touch, Pressure

Gamma = Muscle Spindles

Delta = Pain, Temp, Touch

Answer 300

A

Preganglionic Autonomic

Answer 301

A

Dorsal Root = Dull pain, Temp, Touch

Sympathetic = Postganglionic

Answer 302

A

At least one month after BMS

At least six months after DES.

Answer 303

A

SBO (Promotility agent so not ideal)
Parkinson’s - Increased risk of rigidity and exacerbation of extrapyramidal symptoms
Pheochromocytoma

Answer 304

A

St. John’s wort is an herbal medication that is taken by patients to treat depression. St. John’s wort induces P450 3A4. This induction causes many anesthetic-related drugs to be metabolized including alfentanil and midazolam.

Answer 305

A

Amino ester (One “i” in name) anesthetics are degraded into the metabolite para-aminobenzoic acid (PABA).

PABA is the reason for reactions to most local anesthetics.

Anaphylaxis to amino amide (2 “i” in the name) anesthetics occurs at an even lower frequency than in amino ester anesthetics.

Methylparaben, a common preservative, is often found in local anesthetics.

Methylparaben is structurally similar to PABA, and therefore cross reactivity is possible.

In the past, PABA was widely used in sunscreens as a UV filter.

Water-insoluble PABA derivatives such as padimate O are currently used in some products.

Answer 306

A

Occurs 30-60 minutes after exposure for allergies but can be immediate if anaphylaxis

More prone = Health care workers, atopic patients, and patients with spina bifida.

Answer 307

A

Increased Chylothorax compared to the right

In the majority of patients the thoracic duct drains into the venous system at or near the junction of the left internal jugular (IJ) vein and the left subclavian vein (SCV)

The most common configuration of the thoracic duct which is found in about 50% of the population involves the thoracic duct originating from the cisterna chyli at around the level of L1, ascending through the abdomen and thorax, and draining into the venous system at the juncture between the left IJ vein and the left SCV.

Variations exist where the thoracic duct drains in the left IJ, left SCV, left brachiocephalic, or left external jugular vein.

Due to the duct’s location, it can potentially be injured during placement of either a central line in the left IJ or in the left SCV.

Answer 308

A

The safety of desflurane exposure in patients with renal failure has been shown in various studies.

The potentially nephrotoxic inorganic fluoride concentrations found in humans after exposure to desflurane are significantly less than that after sevoflurane exposure

Unsure about this compared to isoflurane?

Answer 309

A

Succinylcholine has a Black Boxed warning specifically for this reason.

Caution should also be used in patients with muscular dystrophies (especially in children who can have potentially undiagnosed disorders), stroke patients, patients with neuromuscular disorders, or intensive care patients with prolonged immobilization.

In some patients, such as muscular dystrophy, hyperkalemia can occur secondary to rhabdomyolysis.

Answer 310

A

<24 hours

It is still appropriate to use succinylcholine to safely secure the airway in these patients if their injury is < 24 hours old, as there has not been enough time to experience nicotinic extrajunctional acetylcholine receptor upregulation.

Answer 311

A

Patients with neuromuscular disease such as a stroke have risk of serious hyperkalemia after succinylcholine.

This usually peaks 7-10 days after insult, but increased K+ release may occur as soon as 2-4 days after denervation injury, or after several days of immobility.

Duration of risk has not been adequately characterized but is suspected to be for 3-6 months.

Answer 312

A

A patient who is already on beta blockers should have beta blocker therapy continued in the perioperative period. Continuation of beta blocker therapy is considered Class 1 Level B evidence.

The reason for the continuation of beta-blocker therapy is that beta blocker withdrawal will allow a rebound causing increased heart rate and increased myocardial oxygen demand in the setting of surgical stress.

This increases the likelihood of a MACE

Answer 313

A

Cardiac risk factors include:

1. Hypertension

2. Cerebral vascular disease

3. Peripheral vascular disease

4. Chronic kidney disease

5. Coronary artery disease

6. Congestive heart failure,

7. Diabetes.

Answer 314

A

#3 = 6 mm

#4 = 6 mm

#5 = 7 mm

#6 = 7 mm

Answer 315

A

#3 = 6mm

#4 = 7mm

#5 = 8mm

Answer 316

A

Tonic inhibitory sympathetic control (T6-L2) predominates, but parasympathetic activation increases contractility.

Therefore, sympathectomy induced by epidural or spinal analgesia results in increased gut motility, especially those involving epidural catheter placement at T12 or higher.

The gastrointestinal hyperperistalsis has the advantage of providing excellent surgical conditions because of a contracted gut.

Epidural analgesia reduces the duration of postoperative ileus

The use of systemic opioids prolongs the duration of an ileus, and epidural analgesia decreases or eliminates the need for systemic opioids by minimizing postoperative pain.

Less pain also translates into decreased amount of catecholamines released which also promotes better gut contraction.

Postoperative epidural analgesia may also have a protective effect on the gastric mucosa because intramucosal pH is higher during postoperative epidural analgesia than during systemic analgesia.

Local anesthetics, given either neuraxial or systemically, have also been shown to improve intestinal perfusion as well as reduce gastrointestinal tract irritation through their anti-inflammatory properties.

Answer 317

A

The intercostobrachial nerve provides sensory innervation to the medial brachium and does not originate from the brachial plexus.

It originates from the T2 dermatome.

Blockade of this nerve is required when an upper arm tourniquet is required and would not be successful with any brachial plexus block technique.

Answer 318

A

Terminal branch of the lateral cord

Motor: Provides innervation to the biceps muscle (elbow flexion).

Sensory: It gives off the lateral antebrachial cutaneous nerve which provides sensory innervation to the lateral forearm (the site of stimulus) and thus would require supplemental block to achieve adequate anesthesia for the operation.

Block by injecting can be supplemented by injecting local anesthetic into the coracobrachialis muscle.

Answer 319

A

Buprenorphine has a high affinity for the μ-receptor with a half-life for dissociation from the receptor between 2-3 hours (compare to fentanyl’s 7 minutes).

This leads to a low-level of physical dependence and prolonged clinical effects, up to 6 hours, despite a metabolic and elimination half-life of 3 hours.

Answer 320

A

Buprenorphine has an analgesic potency at low doses that is 25-40 times that of morphine.

Answer 321

A

Cytokines and Antibodies to Leukocyte Antigens

Answer 322

A

Donor Lymphocytes against a recipient

Answer 323

A

recipient antibody and complement attack on donor cells

result of recipient antibody and complement attack on donor cells

typically secondary to antibodies associated with the Rh, Kidd, or Kell systems

Answer 324

A

recipient antibody and complement attack on donor cells

result of recipient antibody and complement attack on donor cells

typically secondary to antibodies associated with the ABO Incompatibility

Answer 325

A

Transfusion-related CMV is a problem primarily for:

Immunocompromised patients

Neonates

Allograft recipients

Asplenic from resection or sickle cell disease.

Answer 326

A

1/438 for CMV

1/366,509 for HBV

1/1,657,722 for HCV

1/1,860,883 for HIV

1/3,394,086 for HTLV.

Answer 327

A

Decreased lung compliance
Increased V/Q mismatch
Increased inspiratory pressures
Increased PaCO2 and decreased blood pH

Answer 328

A

Increased SVR, increased PVR, increased MAP
Increased cardiac filling (e.g. increased thoracic pressure + head-down position)
Arrhythmias (tachy or brady)
Decreased venous return (e.g. vena cava compression + head-up position)
Decreased ejection fraction
Decreased renal blood flow
Decreased splanchnic perfusion

Answer 329

A

Benefits:

Stage II (excitation) is generally avoided with high concentrations of sevoflurane used for induction in the adult population.

Sevoflurane also has been administered by mask as an approach to the difficult adult airway because it preserves spontaneous ventilation and does not cause salivation.

The traditional “awake look” in the suspected difficult airway (where intravenous drugs are titrated to a level that allows direct laryngoscopy in the awake patient) has been modified to consist of spontaneous ventilation of high concentrations of sevoflurane until laryngoscopic evaluation is tolerated.

Answer 330

A

Antagonist of calcium influx through the slow channels of cell membranes

Arterial Dilator which decreases afterload and decreases SVR

Coronary Dilator (Angina/Spasms) with minimal effect on preload

Sympathetic activation (25% get tachycardia - NOT Baroreceptor mediated)

Increases cardiac contractility

Answer 331

A

Nicardipine, nitroglycerin, and sodium nitroprusside inhibit hypoxic pulmonary vasoconstriction.

Answer 332

A

Drugs that typically follow zero-order kinetics are THE PAW: theophylline, heparin, ethanol, phenytoin, aspirin, warfarin.

Answer 333

A

FENa = [(PCr x UNa ) / (PNa x UCr)] x 100

Answer 334

A

Uremia can lead to impaired hemostasis through a variety of mechanisms including, but not limited to:

1. Interference with von Willebrand factor (vWF) formation and release leading to impaired platelet activation at the site of vascular injury. ‘

Normally, platelets are activated and subsequently aggregate by binding to sub endothelial vWF.

Function of glycoprotein IIb-IIIa (GPIIb-IIIa) is abnormal in uremia.

This protein found on the surface of platelets is a receptor for fibrinogen, fibronectin, and vWF, and assists in platelet activation and aggregation.

Prostacyclin and nitric oxide synthesis are each increased in uremia.

These two compounds have platelet inhibitory effects.

Decreased tissue factor (factor III) activity.

This enzyme complexes with factor VIIa to activate factor X to factor Xa which converts prothrombin to thrombin.

Answer 335

A

Back pain following a large volume injection of 2-chloroprocaine is not an indication for imaging of the spine.

Back pain following injection of large volumes of 2-chloroprocaine can cause muscle spasms.

2-chloroprocaine may contain the preservative disodium ethylenediaminetetraacetic acid (EDTA).

EDTA is a known chelator of calcium.

Larger volumes of 2-chloroprocaine chelate the calcium of nearby muscle, which causes local muscle spasms.

These spasms are transient and self-relieving.

There is no need for treatment or imaging unless other signs and symptoms are present.

However, there are preservative free formulations of 2-chloroprocaine readily available so this side effect is less commonly seen.

Answer 336

A

CV: bradycardia, hypotension, Prolonged QTc

Pulmonary: pulmonary toxicity (with a pulmonary fibrosis appearance)

GI: Elevated LFT

Endocrine: hypothyroidism (20% of patients), life-threatening hyperthyroid storm

Dermatological: Blue/Gray Skin and Hypersensitivities

Answer 337

A

Antibody mediated destruction of parenchyma or cytotoxic process

Though the risk of developing side effects rises with the dosage of amiodarone, there is no set dosage limit at which it will occur.

amiodarone-induced pulmonary toxicity correlates more with the total cumulative dose than with the daily dose or plasma concentration.

Answer 338

A

Hepatically

Answer 339

A

Ester type local anesthetic, and like other esters is broken down by plasma cholinesterases.

The amide local anesthetics undergo hepatic metabolism.

Answer 340

A

2-chloroprocaine is so rapidly metabolized and has such low systemic toxicity that it can be delivered in much higher concentrations, up to 3%.

Answer 341

A

Lipid Solubility primary determinant of potency in local anesthetics.

Answer 342

A

Protein Binding primary determinant of duration of local anesthetics.

Answer 343

A

Pain control is of short duration and stops almost immediately upon deflation of the tourniquet. One important complication of IVRA is systemic toxicity of local anesthetics.

For this reason, it is recommended that the tourniquet not be let down less than 20-30 minutes of local anesthetic injection

The tourniquet should be gradually released to avoid a massive washout of local anesthetic, and long-acting anesthetics such as bupivacaine should be avoided.

Dose = Amount: 40-50 mL of 0.5% Lidocaine (200-300 mg) Example dose would be 12-15 mL of 2% lidocaine (240 - 300 mg) or higher volume of dilute lidocaine

Answer 344

A

Intravenous regional anesthesia (IVRA), also called Bier block, is an alternative to a peripheral nerve block for short (ie, 30 to 45 minutes) procedures on the hand and forearm such as carpal tunnel release, Dupuytren’s contracture release, or reduction of wrist fracture

Answer 345

A

The point of maximal amplitude of oscillations corresponds to the mean arterial pressure (MAP).

Answer 346

A

MAPS = Most reliable

The values of systolic and diastolic pressures are determined using formulas that detect the rate of change in the oscillations.

Thus, systolic and diastolic pressures are less reliable than the mean arterial pressure.

Diastolic blood pressure measurement is more likely to be affected by movement since this would cause changes of similar pressure magnitude, which makes the diastolic pressure the least reliable.

Answer 347

A

Intraocular pressure following succinylcholine administration can increase 5-15 mm Hg despite pretreatment with a NDNB.

Answer 348

A

Cardiac side effects are more often seen with repeat dosing in children (Bradycardia and Asystole) and can be attenuated with the use of glycopyrrolate or atropine.

Succinylcholine more commonly causes tachycardia, mediated by catecholamine release.

Answer 349

A

Administration of a NDNB can blunt the rise in ICP seen with succinylcholine use. Similar to IOP, inadequate anesthesia, elevated blood pressure, and insufficient neuromuscular blockade during tracheal intubation can elevate ICP higher than succinylcholine alone.

Intraocular pressure following succinylcholine administration can increase 5-15 mm Hg despite pretreatment with a NDNB. The exact mechanism is unknown, but studies have shown that the increase in IOP occurs despite detachment of extraocular muscles.

This has led to the belief that the mechanism most likely is intraocular. Currently, there is widespread recommendation to avoid succinylcholine in open-eye injuries. Importantly, inadequate anesthesia, elevated blood pressure, and insufficient neuromuscular blockade during tracheal intubation can elevate IOP higher than succinylcholine alone.

There is minimal evidence that succinylcholine has led to extrusion of eye contents or blindness.

Answer 350

A

Blue, green, and to a lesser extent, black nail polish cause falsely low oxygen saturations to be displayed by standard two-wave pulse oximeters by interfering with the differential absorption of 660 and 940 nm light.

Answer 351

A

1-2 mg/kg over 3-5 minutes

The drug acts as an electron receptor for NADPH methemoglobin reductase and enhances the enzyme’s effects up to 5-fold, leading to rapid reduction of MetHb to normal Hb.

Methylene blue provides an electron acceptor for the reduction of methemoglobin using NADPH produced from the hexose phosphate pathway.

Answer 352

A

CaO2 = [(SaO2)(Hb x 1.34)] + (0.0031 x PaO2)

Where SaO2 is arterial oxygen saturation, Hb is hemoglobin, and PaO2 is partial pressure of arterial oxygen.

Answer 353

A

Insulin plasma concentration initially decreases during surgery due to sympathetic activity, which inhibits pancreatic β-cells via α-adrenergic receptors.

Postoperatively insulin concentration usually increases due to hyperglycemia (although the increase is blunted compared non-stressed state)

The stress response also causes insulin resistance.

Answer 354

A

T3/T4

GRH

Answer 355

A

Patients with space-occupying extradural lesions or those that reduce the cross-sectional area of the spinal cord are most at risk for permanent or worsening neurologic injury from a neuraxial anesthetic.

Examples of such lesions include:

Tumors

Severe spinal stenosis

Epidural lipomatosis

Ligamentum flavum hypertrophy

Ependymoma

In these patients, it is generally recommended to avoid neuraxial anesthetic techniques unless the benefits significantly outweigh the risks.

Answer 356

A

Relative Contraindications

Some CNS diseases including:

Multiple sclerosis

Traumatic spinal cord injury

Post-polio syndrome only very rarely (<0.3%) develop exacerbation of their disease following neuraxial anesthesia.

Preexisting diabetic neuropathy or other sensorimotor neuropathies have an approximately 0.5-1% incidence of new or worse neurologic deficit following neuraxial anesthesia (higher than the general population).

Answer 357

A

Tachycardia and Hypotension

Increased HR (Chemically similar to Atropine)

Meperidine is structurally similar to atropine and, accordingly, demonstrates atropine-like effects including tachycardia.

Meperidine was initially studied as an anticholinergic agent before being discovered as an analgesic.

The physiologic effects of meperidine differ from other opioids mainly due to two factors:

atropine-like drug effects

weak local anesthetic properties.

At standard analgesic doses, meperidine is associated with hemodynamic stability. However, high doses cause hypotension and tachycardia.

The hypotension is likely attributed to histamine release.

Answer 358

A

In addition, high concentrations of meperidine decrease cardiac contractility, an effect resistant to naloxone.

This is due to the local anesthetic effects of meperidine.

Answer 359

A

Nicardipine is primarily an ARTERIOLAR vasodilator and decreases left ventricular afterload and systemic vascular resistance with minimal effect upon preload. It is a short acting (t1/2 = 3-14 minutes) dihydropyridine calcium channel blocker that does not significantly decrease cardiac inotropy and may actually cause reflex tachycardia.

Answer 360

A

Recombinant form of human brain natriuretic peptide (BNP) which is normally produced by ventricular myocardium.

Brain natriuretic peptide functions as a counter-regulatory hormone to angiotensin II, norepinephrine, and endothelin.

Therefore, nesiritide facilitates cardiovascular fluid homeostasis by down-regulating the renin-angiotensin-aldosterone system, suppressing the sympathetic nervous system, suppressing endothelin production, and stimulating cGMP causing arterial AND venous dilation. Its net effects are vasodilation, natriuresis, and diuresis.

Answer 361

A

It has a rapid onset of action and an elimination t1/2 of 15 min.

Nesiritide was once FDA approved for the treatment of acutely decompensated congestive heart failure (CHF).

Recent studies, however, do not recommend its routine use in patients with d ecompensated CHF.

Answer 362

A

Coagulation is impaired by even mild hypothermia which appears to be due to a cold-induced defect in platelet function. This has been shown to increase blood loss in hip arthroplasty.
Drug metabolism can be impaired by hypothermia, the degree depends on the specific medication and the degree of hypothermia.
The incidence of wound infection is likely one of the most serious complications associated with hypothermia in terms of morbidity.
Hypothermia impairs immune function and decreases wound oxygen delivery secondary to thermoregulatory vasoconstriction to that area.
Patient satisfaction may be negatively impacted by hypothermia as patients often recall unpleasant sensations of being cold in the recovery room; this feeling can last hours even with mild hypothermia. 6. Finally, patient shivering can cause serious discomfort and complications since shivering increases oxygen consumption and can lead to ischemia in at risk patients (resulting in myocardial ischemia and even stroke).

Answer 363

A

Resting coronary blood flow in the average adult is around 250 ml/min, which represents approximately 5% of the total cardiac output.

Answer 364

A

Hence, CPP of the LV (CPPLV) is equal to difference between aortic diastolic pressure (AoDP) and left ventricular end diastolic pressure (LVEDP):

CPPLV = AoDP - LVEDP.

Answer 365

A

The RV receives its greatest perfusion during peak/late systole and early diastole and is least perfused during early systole.

Answer 366

A

Myasthenia gravis is an autoimmune disorder with antibodies against the extrajunctional nicotinic acetylcholine receptor resulting in weakness, enhanced response to nondepolarizing neuromuscular blockade, and resistance to succinylcholine but does not result in upregulation of postjunctional acetylcholine receptors.

Augments Block to Roc

Resistant to Succinylcholine but NOT contra

Answer 367

A

A gas mixture of 75% N2O can expand a pneumothorax to double its size in 10 minutes and to 3 times its size in 30 minutes.

Answer 368

A

High BGPC = High Solubility = Greater Uptake = Slower Onset

Answer 369

A

How anesthetic split between two phases (Blood and Gas)

Answer 370

A

FA / FI = Yields value that can be used to assess relationship of delivered anesthetic by:

Ventilation

Degree of Anesthetic Uptake/Removal

Answer 371

A

*Clinical risk factors for coronary disease include:**
A history of ischemic heart disease
Congestive heart failure
History of stroke
Diabetes
Chronic kidney disease.

Answer 372

A

Severe COPD was once considered contraindication to beta-blocker therapy, however it is no longer considered contraindicated.

Many beta-blockers are cardiac-specific and safe in patients with COPD. The ACC/AHA 2014 guidelines recommend that patient’s on beta-blockers should have them continued through the perioperative period.

Additionally, it is suggested that patients at intermediate or high risk for myocardial ischemia may benefit from perioperative beta-blocker therapy.

Answer 373

A

The ACC/AHA 2014 guidelines recommend that patients on beta-blockers should have them continued through the perioperative period. Patients with 3 or more risk factors for coronary artery disease may also benefit from beta-blocker therapy preoperatively.

Clinical risk factors for coronary disease include:

*- A history of ischemic heart disease
Congestive heart failure
History of stroke
Diabetes
Chronic kidney disease.**

Answer 374

A

*Class 1** – benefit is greater than risk and recommendation should be followed
*Class 2a** – benefit greater than risk and it is reasonable to perform therapy
*Class 2b** - benefit is slightly better or equal to risk and treatment should be considered
*Class 3** – no benefit and may be harmful

Answer 375

A

Factors that cause a leftward shift and an increased slope of a carbon dioxide ventilatory response curve include arterial hypoxemia, metabolic acidemia, surgical stimuli, and certain CNS pathologies

Volatile anesthetics at ≤1 MAC cause a rightward, parallel shift of the VRC. Volatile anesthetics >1 MAC reduce sensitivity to elevated PaCO2, cause a rightward shift, and reduce the slope of the VRC.

Opioid, barbiturate, and other sedative-hypnotic medication administration shift the VRC to the right and depress the slope, in a dose-dependent manner. The result is a reduced minute ventilation and higher baseline PaCO2 therefore reducing minute ventilation.

Answer 376

A

14 days after balloon angioplasty

Patients should wait 14 days after balloon angioplasty before elective surgery.

30 days after Bare Metal Stent

Dual Antiplatelet therapy w/ aspirin continuation only in the perioperative period

60 days if no coronary intervention

Acute coronary syndrome patients should wait 60 days prior to scheduling elective surgery.

180 days after Drug Eluting Stent (EVeroliumus eluting stents)for elective non-cardiac surgery

Answer 377

A

A = Diuretics

B = Vasoildators (ACE-Inhibitors or Nitroglycerine)

C = Milrinone

D = Ionotropes (Epi, Norepi)

Answer 378

A

The most commonly described side effects of spironolactone are hyperkalemia, hyponatremia, gynecomastia, and impotence.

Answer 379

A

The analgesic properties of ketamine are primarily NMDA receptor-mediated at low ketamine doses with proportionally more opioid receptor*-mediated effects at *higher doses.

Answer 380

A

Lowering heart rate decreases cardiac work since fewer muscle contractions occur over a given period of time. (less ATP thus less oxygen)

Since the heart is doing less work, there is a corresponding decrease in oxygen demand.

In addition, lowering heart rate will increase the amount of time the heart spends in diastole. Since coronary perfusion occurs primarily during diastole, a longer time spent in diastole improves myocardial oxygen supply. (Time during perfusion)

Answer 381

A

CPP = (Aortic DBP – LVEDP)

Answer 382

A

Wall tension = (LVEDP x radius) / (2 x LV wall thickness)

Where: LVEDP = left ventricular end diastolic pressure.

Answer 383

A

Myocardial oxygen supply is determined by the arterial oxygen content of blood, coronary perfusion time, coronary pressure.

Myocardial oxygen demand is determined by myocardial work which is primarily dependent on heart rate and wall tension.

Heart rate is a unique variable in that it plays a role in determining both myocardial oxygen supply and demand.

Answer 384

A

Midazolam causes anterograde but not retrograde amnesia, even at large doses. Typical anxiolysis doses (e.g. 2mg IV in an adult) do not guarantee amnesia.

Answer 385

A

Primarily metabolized to oxymorphone-3-glucuronide and 6-hydroxy-oxymorphone.

The only active metabolite of oxycodone is oxymorphone.

In patients with renal insufficiency receiving oxycodone, the elimination half-life is lengthened and the excretion of metabolites is impaired potentially resulting in a prolongation of its clinical effect.

Answer 386

A

Free Hydromorphone (Accumulates in renal failure)
Hydromorphone-3-glucoronide (No analgesia and have be neuroexcitatory)

Answer 387

A

Morphine-3-glucuronide (M3G) (55%)

Morphine-6-glucuronide (M6G) (10%)

Normorphine (4%)

Parent compound (10%)

Answer 388

A

Morphine-6-Glucuronide (Active compound: 10%)

Answer 389

A

Respiratory depression

enterohepatic cycling and slow penetration of the blood-brain barrier with equally slow equilibration with systemic circulation; effects are not reversed by dialysis.

Prolonged sedation

Myoclonus

Seizures

Answer 390

A

Halothane decreases SBP mainly by reducing cardiac output (NOT SVR)

Other anesthetics = Decrease in SVR, while CO is maintained

Answer 391

A

Succinylcholine after neostigmine

Following neostigmine administration, a dose of succinylcholine will result in an increased duration of phase I blockade when compared to the duration of action of succinylcholine administered alone.

Phase I augmentation lasts about 30 minutes on average.

Multiple studies have shown that following neostigmine administration for nondepolarizing muscle relaxation reversal, a subsequent dose of succinylcholine will result in prolonged duration of action of the succinylcholine (mean duration 25-35 minutes).

The increase in duration is likely complex and is not solely the result of plasma cholinesterase inhibition.

Answer 392

A

A phase II block is likely due to the interaction of succinylcholine on the prejunctional acetylcholine receptors.

Prejunctional receptors are blocked by the higher concentration of succinylcholine leading to a decrease in cholinergic transmission and competition with the drug at the postsynaptic receptors. A decrease in plasma cholinesterase activity (either from congenital or acquired causes) can also result in prolonged blockade.

Many medications used for anesthetic maintenance reduce plasma cholinesterase activity including remifentanil, esmolol, ester local anesthetics, and etomidate.

Answer 393

A

Head-down position

Suction

FiO2 of 100%

Deepen anesthetic

Answer 394

A

Interference with Platelet Adhesion and clot formation by decreasing glycoprotein 2b/3a availability on platelets

Platelets are not able to achieve the appropriate conformation to bind fibrinogen, which negatively affects platelet aggregation

Answer 395

A

Originates from the aorta between the T9 and T12 vertebral segments in 75% of the population.

Answer 396

A

Spinal Cord Perfusion Pressure (SCPP) Equation

MAP - Intrathecal Pressure or CSF pressure (SCPP = MAP - CSF pressure).

Improve SCPP

1. Increase the MAP to > 90 mmHg (if suspected involvement)

2. Reduce CSF pressure to < 10 mmHg using a lumbar CSF drain.

Answer 397

A

Compromise: Interruption of the great radicular artery → ASA syndrome

Symptoms:

Motor Tract involved

Bilateral lower extremity paraplegia

Bowel and bladder dysfunction.

Dorsal Columns / Sensory NOT involved

Spared Sensation and proprioception (posterior portion of the spinal cord is supplied by two PSAs.)

Answer 398

A

Thoracoabdominal aortic aneurysm (TAAA) repair occurs in 10-20% of patients depending on urgency of procedure, location of the lesion, and duration of ischemia.

Paraplegia in 10-20% of surgeries

With aortic cross clamping, there may be significant hypoperfusion of the spinal cord anteriorly.

Answer 399

A

Delayed-onset paraplegia is the new onset of neurologic dysfunction several hours to days following surgery in a patient who otherwise woke up without neurologic deficits.

The same principles of SCPP optimization persist and include increasing MAP via vasopressors and/or emergent placement of a spinal drain.

This is an important concept since a spinal cord that was adequately protected during surgery is still at risk for ischemia and infarction postoperatively.

Answer 400

A

IICEBALLS: intravenous > intercostal > caudal > epidural > brachial plexus > axillary > lower limb > subcutaneous

Answer 401

A

Alveolar Gas Equation

PAO2 = FiO2(PB – PH2O) – PCO2 / RQ

*_PAO2_* = alveolar oxygen partial pressure
FiO2 = fraction of inspired oxygen
PB = barometric pressure
PH2O = vapor pressure of water
RQ = respiratory quotient

Ex: If PCO2 is 80 mmHg, then your PAO2 would be 50 mmHg.

Answer 402

A

In healthy patients, minute ventilation will normally increase linearly by approximately 2 L/min for every 1 mmHg increase in PaCO2.

Answer 403

A

Volume of Distribution (Vd) = Drug dose / Plasma concentration

The volume of distribution does not have an actual physical correlate in plasma volume. Rather, it is the theoretical size of the plasma compartment that would explain the observed plasma concentration if all of the drug given was only distributed in the plasma. Because of this, it is sometimes referred to as the “apparent” volume of distribution.

Answer 404

A

Affinity of the drug for tissue components* (tissue proteins, tissue lipids) relative to its *affinity for plasma components (plasma proteins).

Tissue proteins may include high-affinity receptor sites.

Tissue lipids are an important binding site, depending on the partition coefficient of the drug in fat (and the individual’s fat volume).

Answer 405

A

“The volume of distribution is the total drug within the body divided by the drug plasma concentration.

It is directly proportional to the unbound drug in the plasma and inversely proportional to the unbound drug in the tissue.

Answer 406

A

As such, drugs that are lipophilic have a higher Vd than drugs that are hydrophilic.

Also, having greater tissue binding will decrease the unbound proportion in the tissue, thus increasing the volume of distribution.”

Answer 407

A

Indications:

Factor replacement in hypofibrinogenemia
von Willebrand disease
Hemophilia A
Massive transfusion after several units of other blood products have been given. Checking fibrinogen levels during massive transfusion can assist with the management of cryoprecipitate.

Answer 408

A

Synthesis:

Cryoprecipitate is made from fresh frozen plasma

Cooled to 4 degrees Celsius slowly.

Cryoprecipitate is high in factors 8 and 13* as well as *fibrinogen* and *von Willebrand factor (vWF).

Answer 409

A

Dosing:

It is often given in a pooled dose of 10 or more units.

Concentration:

Contains approximately 200 mg/unit of fibrinogen.
1200 mg/dL: 1 unit is 12.5cc

Therefore, administration of 10 units would add 2 gm of fibrinogen.

1. ICU

Ten units of cryoprecipitate (2 grams) will typically raise a 70kg patient’s fibrinogen by 70 mg/dL

2. Intraop

FIBTEM A10 <10mm

Goals (Ask surgeon if we are acutely bleeding or oozing)

Acute Hemorrhage = We need FIBTEM A10 ~ 18 mm
Oozing = We need FIBTEM A10 ~ 9 mm

Treat with Fibrinogen (2 mm FIBTEM A10 increase with 1000 mg of Fibrinogen)

Answer 410

A

Glossopharyngeal
Recurrent laryngeal
Superior laryngeal

Answer 411

A

Base of Tongue

Vallecula

Anterior Epiglottis

Tonsils

Answer 412

A

Nerve Block

Topical application of local anesthetic in the gutters of the pharyngeal folds near the base of the tongue for 5-10 minutes or with injection of local anesthetic at the base of the fold in the floor of the mouth.

Answer 413

A

Watch out for carotids!

If blood aspirated, needle redirection medially should occur.

The glossopharyngeal nerve is the sensory nerve associated with the gag reflex

Answer 414

A

Motor and Sensory nerve, motor involved with cough reflex

Primary motor nerve of the larynx

Sensory innervation to the vocal folds and trachea

Answer 415

A

Anesthesia of this nerve is provided by transtracheal injection of local anesthetic after air is aspirated with puncture through the cricothyroid membrane or through aerosolization of local anesthetic and having the patient breathe it in.

Answer 416

A

Internal and External Branch

Answer 417

A

Base of the tongue

Epiglottis

Aryepiglottic folds

Arytenoids

Answer 418

A

It can be blocked by cotton soaked in local anesthetic applied with a right-angled clamp into the piriform sinuses for 5-10 minutes but is often blocked by initial topicalization of the pharynx.

Injections can also be performed after walking off the cornu of the hyoid bone through the thyrohyoid membrane

Answer 419

A

Motor innervation to the cricothyroid muscle, the only laryngeal muscle not innervated by the recurrent laryngeal nerve.

Answer 420

A

Clark, galvanic, and paramagnetic electrodes measure oxygen

Answer 421

A

Severinghaus electrode measures CO2

Answer 422

A

Sanz electrode measures pH

Answer 423

A

CPPLV = AoDP - LVEDP

Hemodynamic variables that increase LVEDP will decrease CPP.

Answer 424

A

Pulmonary artery occlusion pressure (PAOP) may be used as a proxy for LVEDP. A decrease in PAOP is generally regarded as a decrease in LVEDP, which leads to an increase in CPP.

Answer 425

A

Aortic Diastolic Pressure - LVEDP

Answer 426

A

Habitus (BMI >30)

Gastroesophageal

High risk for aspiration of gastric contents including

Known or potential for full stomach (NOT NPO)

Hiatal hernia

Gastroesophageal reflux disease

Intestinal obstruction

Delayed gastric emptying

Pulmonary

Poor lung compliance

High airway resistance

Airway

Difficult Airway

Glottic or subglottic airway obstruction

Limited mouth opening (generally less than 1.5 cm).

Answer 427

A

The 11-β hydroxylase enzyme converts deoxycorticosterone to corticosterone and 11-deoxycortisol to cortisol.

Answer 428

A

Bohr Effect

Answer 429

A

Midazolam bioavailability among routes of administration (greatest to least):

intravenous > intramuscular > intranasal > rectal > oral.

Oral bioavailability is highly dependent on dose; bioavailability is lower with higher doses.

This means that rectal bioavailability could potentially be lower than oral, but again it is dose dependent.

Answer 430

A

>3 years
Duration of surgery (>30 minutes)
Type of Procedure (Strabismus and T&A)
Patient or family history of PONV

Zero, 1, 2, 3, or 4 of these risk factors impart a risk of postoperative vomiting of 9%, 10%, 30%, 55%, and 70% respectively in pediatric patients.

Answer 431

A

Zofran 0.1 - 0.15 mg/kg

Dexamethasone 0.15 mg/kg

Answer 432

A

Weakness
Reversal of nondepolarizing neuromuscular blockade is achieved by administering an AChE inhibitor. (Neostigmine).

NMBD = competitive antagonists and compete with acetylcholine (ACh) in the synaptic cleft. The chances that ACh will bind to ACh receptors (instead of the NMBD) increases with AChE inhibition (Neostigmine)

Excessive inhibition of AChE can lead to prolonged elevations in synaptic ACh concentrations.

Prolonged exposure to ACh can lead to both presynaptic and postsynaptic inactivation of sodium channels.
Inactivation of sodium channels prohibits depolarization from occurring. 3. In addition, both presynaptic and postsynaptic ACh receptors become desensitized to ACh.

Answer 433

A

Restrictive Disease

Reduced diaphragmatic excursion leads to decreased lung volumes

FVC - Low

FEV1 - Low

FEV1/FVC - Normal or even high

FEF 25-75% - Normal

FRC - Low

TLC - Low

Answer 434

A

Obstructive Disease with PFT will show

FVC - Normal or Increased

FEV1 - Decreased

FEV1/FVC - Decreased

FEF 25-75% - Decreased

FRC - Normal or increased

TLC - Normal or increased

Answer 435

A

The forced expiratory flow during the middle 50% of the FVC (FEF25-75%)

another way of saying this

Forced expiratory flow (FEF) is the flow (or speed) of air coming out of the lung during the middle portion of a forced expiration

Normal ranges for FEF25-75% are typically 80-120% of the predicted value.

Wikipedia

Values ranging from 50-60% and up to 130% of the average are considered normal

Answer 436

A

Ketorolac can decrease GFR, especially when administered for greater than 5 days, via inhibition of afferent renal artery vasodilation.

Blocks prostaglandins which vasodilate the afferent renal artery.

Answer 437

A

Both = Screen for ABO, Rh, Antibody

T&C = Donor RBC and patient serum for antibody screening

Answer 438

A

Factors that decrease release of acetylcholine:
1) Antibiotics (clindamycin, polymyxin)

Answer 439

A

Factors that decrease release of acetylcholine:

*Magnesium**: antagonizes calcium
*Calcium**: Hypocalcemia

Answer 440

A

Factors that decrease release of acetylcholine:
Anticonvulsants

Answer 441

A

Factors that decrease release of acetylcholine:
Diuretics (furosemide)

Answer 442

A

Factors that decrease release of acetylcholine:
Eaton-Lambert syndrome: inhibits P-type calcium channels

Myasthenia gravis is due to antibodies destroying post-synaptic acetylcholine receptors. Acetylcholine release from nerve terminal is not affected.

Answer 443

A

Calcium channel blockers (nifedipine, diltiazem) do not affect P-channels. These drugs affect L-type calcium channels.

Answer 444

A

Both the botulinum and tetanus toxin inhibit SNARE proteins.

However, botulinum* toxin acts at the level of the *peripheral nerve, and the tetanus toxin acts at the central nervous system.

Botulinum –> inhibits SNARE –> decrease acetylcholine release (peripheral nerve)
Tetanus –> inhibits SNARE –> inhibits GABA neurons (CNS)

Answer 445

A

“BLEACH P”

Age ≥ 59
BMI ≥ 32
Chronic Liver disease
COPD requiring chronic bronchodilator use
Peripheral vascular occlusive disease
High-risk surgery
Emergency surgery

Answer 446

A

FRC is the capacity in the lungs after end expiration of a normal tidal volume and consists of the expiratory reserve volume (ERV) and the residual volume (RV).

Answer 447

A

Closing capacity is the capacity during which airway closure begins to occur and consists of the closing volume and residual volume.

Answer 448

A

A mnemonic for factors that decrease FRC is PANGOS:

Pregnancy

Ascites

Neonate

General Anesthesia

Obesity

Supine position.

Answer 449

A

A mnemonic for factors increasing closing capacity is ACLS-S:

Age

Chronic bronchitis

LV failure

Smoking

Surgery

Answer 450

A

Pancuronium is eliminated primarily by the kidney and therefore should be avoided in renal failure.

Answer 451

A

Glucagon is generally not considered a first line therapy for low cardiac output (CO) states, but may be beneficial in the following situations after conventional therapies have failed:

1. Low CO following cardiopulmonary bypass (CPB)

2. Low CO following myocardial infarction

3. Chronic congestive heart failure

4. Low CO from excess β-blockade

5. Anaphylactic shock with refractory hypotension

Answer 452

A

Anaphylaxis (refractory to epinephrine) in patients on beta-blocker therapy (off-label use): IV:

Initial: IV 1 to 5 mg bolus

Followed by an infusion of 5 to 15 mcg/minute

Titrate the infusion rate to achieve an adequate clinical response (Lieberman 2015).

Beta-blocker overdose

IV: 3 to 10 mg bolus; if no clinical response may repeat bolus dose; if clinical response with bolus, start continuous infusion at 3 to 5 mg/hour;

titrate infusion rate to achieve adequate hemodynamic response (ACC/AHA/HRS [Kusumoto 2018]; AHA [Vanden Hoek 2010]; Barrueto 2019).

Answer 453

A

This patient is taking St. John’s Wort which induces cytochrome P450 isoenzymes and increases the metabolism of cyclosporine.

This can result in subtherapeutic drug levels and an i_n_creased risk of transplant rejection

Warfarin therapy is therefore unreliable in patients taking St. John’s Wort and puts them at risk for DVT and thromboembolism.

Answer 454

A

The lipid solubility of an opioid is a prime determinant of the onset and duration of action of the drug as it affects how easily the drug is able to cross cellular (lipid) membranes.

Answer 455

A

An opioid with a pKa less than physiologic pH (~7.4) will have a much greater nonionized fraction whereas an opioid with a pKa >7.4 will have a greater ionized fraction.

Lower pKa = Increased non-ionized fraction = Faster onset

Answer 456

A

Both FEV1 and FVC are decreased proportionally so that the FEV1/FVC ratio is preserved, i.e. obesity behaves like a restrictive defect.

Answer 457

A

O DAMN

O = Oxygen

D = Drugs (Vapor, Sedative/Hyponotic/NMBD/Atypical Pseudocholinesterase, Benzo,)

Antagonism with Naloxone, Nalbuphinie, Sugammadex, Physostigmine (For Scopalamine), ETOH or intoxication

Altered Metabolic Derangments

Hypoglycemia
o Assess blood glucose level
Hypoxemia and/or hypercarbia
o Assess vital signs including pulse oximetry and end tidal CO2.
o Obtain arterial blood gas. Continue mechanical ventilation until corrected.
Hypothermia/hyperthermia
o Assess vital signs including temperature (E)
Acidosis
o Obtain arterial blood gas and correct underlying disorder as necessary
Hyponatremia (e.g. after urologic surgery)
o Obtain metabolic panel and correct as necessary

N = Neurological insults

New stroke, either ischemic or hemorrhagic
o Perform full neurologic exam if able (pupils, cranial nerves, reflexes, withdrawal to pain)
o Consider CT scan or MRI scan if adequate concern or suspicion
Seizure or post-ictal state
Increased intracranial pressure

Answer 458

A

Delayed Emergence Rapid Panel

Vital signs (including temperature)

Twitch monitor

Neurologic Exam (pupils, cranial nerves, reflexes, response to pain)

Fingerstick glucose

ABG with electrolytes

Make arrangements for naloxone, flumazenil, physostigmine, imaging (ex. CT scan)

Answer 459

A

Included under drug effects are:

Residual anesthetic (volatile, propofol, barbiturates, ketamine)

Excess narcotics – can be reversed by naloxone (40 ucg boluses) – remember it’s short-acting

Preoperative sedatives – too much midazolam? – reversed by flumazenil 0.2 mg q1min up to 1 mg

Physostigmine 1.25 mg IV can reverse cholinergic effects (ex. scopolamine) and possibly the effects of anesthetic agents (Stanford Delayed Emergence Protocol)

Inadequate reversal or no reversal of muscle relaxation or rarely pseudocholinesterase deficiency – edrophonium/atropine work faster (1-2 mins) than neostigmine/glycopyrrolate (peak effect around 10 mins) and may be indicated in this setting

Acute alcohol intoxication or other illicit drugs rendering unconsciousness extending the length of the anesthetic

Answer 460

A

Ulnar: Black is Distal, Red is proximal

Face: Black is aligned with tragus, Red is above

Answer 461

A

Corrugator Supercilii

Answer 462

A

Induction = Corrugator Supercilii

It is the best comparison for abdominal muscle paralysis as the diaphragm and abdominal muscles are also relatively resistant to neuromuscular blockade. These muscles are the first to recover from neuromuscular paralysis. Corrugator supercilii monitoring is reflective of laryngeal muscle paralysis and may be used to assess for adequate intubating conditions.

Emergence = Adductor Pollicis

The adductor pollicis muscle is innervated by the ulnar nerve and causes adduction of the thumb. The adductor pollicis is more sensitive to neuromuscular blockade than the corrugator supercilii. Therefore the adductor pollicis is less representative of abdominal muscle paralysis. The adductor pollicis is a commonly monitored muscle to assess neuromuscular blockade as it is often accessible, visible, and correlates well with recovery of laryngeal muscle function during extubation. A primary benefit of monitoring the adductor pollicis is upon emergence.

Answer 463

A

100Hz for 5 seconds correlates to about a TOF ratio of 0.85 if sustained.

Answer 464

A

1: TOF <0.7
2: TOF 0.7 - 0.9

Answer 465

A

2-2.5 x the IV dose (2.5 mg diluated in 5-10 mL of sterile water)

Answer 466

A

An equation for this is: Amount FFP Needed (mL) =

(Target Level - Present Level) * kg

Answer 467

A

0 100
4-1.6 40
7-1.8 30

1.9-2.1 25

2-2.5 20
6-3.2 15

4.0-4.9 10

>5.0 5

Answer 468

A

For example, let’s say we have a 70kg patient who is bleeding with an INR of 7.5 and our goal INR is 1.4.

INR of >5 = 5% activity

INR of 1.4 = 40% activity

We would need (40% - 5%) * 70 kg, which is 2450 mL of FFP to make this correction. A single unit of FFP typically is 200-250 mL.

Answer 469

A

5 4 units
0 3 units
8 2 units

Answer 470

A

The proliferation of extrajunctional acetylcholine receptors in muscle in paralyzed limbs can lead to an increased response (T4:T1) to peripheral nerve stimulation following non depolarizing neuromuscular blockade compared to a normal non paralyzed limb in the same patient.

Answer 471

A

EAST

Eplerenone

Amiloride

Spironolactone

Triamterene

Answer 472

A

SaO2 - [VO2 / (CO * Hgb * 4/3))]

Answer 473

A

14 days after balloon angioplasty

30 days after Bare Metal Stent

60 days if no coronary intervention

180 days after DES for elective noncardiac surgery.

Answer 474

A

Pulmonary Complianace (Elastic Resistance)

Positioning

Abdominal Insufflation

Decrease pulmonary compliance

Trendelenburg Position

Intrinsic Disease

Ascites

Intrinsic Lung Disease

Obesity

Acute Events

Pulmonary Edema

Tension Pneumothorax

Answer 475

A

Two things can be happening when the peak inspiratory pressure is high

Peak pressure is high with a normal plateau pressure, indicating a problem with resistance

Peak pressure is high with an elevated plateau pressure (normal < 25 cm H2O) demonstrating that there is a problem with lung and/or chest wall compliance

Answer 476

A

Problem is with airway resistance

Airway compression
Bronchospasm
FBO
Kinked ETT tube
Mucuous Plug
Secretions

Answer 477

A

Stroke Volume (SV) 60 - 100 mL/beat

Stroke Volume Index (SVI) 33 - 47 mL/m^2/beat

Answer 478

A

CO = BP/SVR

Answer 479

A

EMLA is a local anesthetic mixture applied transdermal to provide anesthesia for the skin.

Eutectic Mixture of Local Anesthetics (EMLA)

EMLA contraindications include:
1. Allergy to amide anesthetics

Concomitant class III anti-arrhythmic drugs (e.g., amiodarone, sotalol)
Congenital or idiopathic methemoglobinemia, infants receiving treatment with methemoglobin-inducing agents.
G6PD

Answer 480

A

Liquid volatile anesthetic (mL/hr) ≈ 3 * FGF (L/min) * % anesthetic vapor.

OR

Answer 481

A

Involves giving fluid and intentionally diluting the patient’s blood prior to significant blood loss.

Blood is withdrawn and stored for later autologous transfusion, and the patient receives the same volume in crystalloid or colloid to maintain euvolemia.

Physiological Consequences:

Blood viscosity will decrease.

The decreased blood viscosity will decrease peripheral vascular resistance

Cardiac output raises to compensate for the anemia.

The increase in cardiac output and decrease in peripheral vascular resistance causes an increase in regional blood flow.

However, even with increases in regional blood flow and cardiac output, there is no increase in oxygen delivery. This is secondary to the significant amount of oxygen that hemoglobin can carry.

Hgb of 7-8 is targeted

Consequently, blood is able to move with less resistance because of the reduced viscosity, and thereby a drop in peripheral vascular resistance occurs with an increase in regional blood flow.

If cardiac output can effectively compensate, oxygen delivery to the tissues at a hematocrit of 25% to 30% is as good, but no better than, oxygen delivery at a hematocrit of 30% to 35%.

Answer 482

A

Under normal circumstances, the brain uses glucose as its sole energy source (No ketone bodies)

During periods of fasting, exercise, or very low carbohydrate diets, the brain will begin to use ketone bodies (acetone, acetoacetic acid, and β-hydroxybutyric acid) as an alternative source of energy.

After 3 days of low blood glucose, ketone body metabolism supplies approximately one-third of the brain’s energy.

After 1-1.5 months, they supply two-thirds of the brain’s energy. Glucose continues to account for the remainder. The increased use of ketones decreases the body’s demand for glucose which allows for decreased catabolism of muscle for conversion of amino acids to glucose.

Answer 483

A

The sodium concentration of standard 5% albumin manufactured in the United States is 145 +/- 15 mEq/L.

Answer 484

A

Extraperitoneal perforation (the most common) causes periumbilical, inguinal or suprapubic pain, whereas intraperitoneal perforation causes diffuse or upper abdominal pain, or referred pain to chest and shoulders.

Answer 485

A

As a side note, keeping the patient awake has the additional benefit of allowing for the detection of TURP syndrome, which is due to hypo-osmolality and hyponatremia and presents with CNS symptoms.

Answer 486

A

Glycine toxicity causes hyperammonemia, which manifests as CNS symptoms and nausea. Transient blindness can also occur.

Answer 487

A

Onset = 7-11 minutes

Duration = 4-6 minutes

Answer 488

A

Reduced MAC requirements

Answer 489

A

The top 3 factors leading to death and permanent brain damage are:

Cardiovascular events (pulmonary embolism, stroke, myocardial infarction, arrhythmia, undiagnosed conditions)

Respiratory events (inadequate ventilation, esophageal intubation, difficult airway)

Equipment issues (failure or misuse)

Answer 490

A

N2O Concentration Bowel Distension After 4 Hours

50% N2O
200% increase

75% N2O
400% increase

80% N2O
500% increase

Answer 491

A

In patients with a coronary supply that is right-dominant, the RCA also gives rise to the AV nodal artery which supplies the AV node.

The most common cause of AV node disruption and resulting complete heart block is a myocardial infarction, most frequently a blockage in the RCA.

Answer 492

A

The SA node is supplied by the RCA in about 60% of cases and by the LCA or its branches in about 40% of cases.

Supply of the SA node does not depend on coronary dominance of the patient.

Answer 493

A

Thyroid Replacement Therapy

Levothyroxine is the preferred therapy because it allows the controlling enzyme systems to regulate TSH secretion as well as conversion to T3.

Liothyronine, the most potent form of thyroid hormone, can be given intravenously though it risks precipitating myocardial ischemia.

Hydrocortisone may also be given because 5% to 10% of patients with myxedema coma also have adrenal insufficiency.

Answer 494

A

*S**noring
*T**ired during the day
*O**bserved apneas
*P**ressure (high blood pressure)
*B**MI > 35
*A**ge >50
*N**eck size
*G**ender (male)

<3 = Low risk of OSA

≥3 = High risk of OSA

Answer 495

A

Sleep studies are scored with an apnea/hypopnea index (AHI).

Mild OSA is defined as 5-15 events/hour of sleep (AHI 5-14).

Moderate OSA is defined as 15-30 events/hour of sleep (AHI 15-29).

Severe OSA is defined as greater than 30 events/hour of sleep (AHI 30+).

Answer 496

A

Sevoflurane metabolism has not resulted in the formation of TFA intermediates and the potential for hepatic toxicity is low.

Instead, sevoflurane metabolism yields a compound hexafluoroisopropanol (HFIP), which does not accumulate and rapidly undergoes phase II biotransformation.

This contributes to the low hepatotoxic potential for sevoflurane.

Answer 497

A

Two types of postoperative liver injuries have been reported to be associated with halothane administration.

The first type is a mild injury characterized by nausea, lethargy, and fever.

The second type, mediated by the patient’s immune system, is severe acute hepatitis with histological findings of widespread hepatic necrosis. This is rare (1 in 15,000 cases on initial exposure) and associated with acute elevations in ALT and AST and onset of jaundice within 2 to 14 days of halothane administration.

Answer 498

A

Desflurane, as a consequence of trifluoroacetic acid (TFA) reactive intermediates, has been implicated in the formation of dangerous immunogenic compounds.

Answer 499

A

It operates on the principle that the amount of infrared light absorbed at a specific wavelength is proportional to the partial pressure of the gas analyzed because absorption will be greater with a greater amount of gas molecules.

Intensity of IR light detected will therefore be inversely proportional to the amount of gas in the sample.

Answer 500

A

Approximately 25-30% of rocuronium is renally excreted.

It is cleared primarily by hepatic uptake* and *hepatobiliary excretion.

Answer 501

A

Citrate intoxication occurs with massive transfusions, most notably with fresh frozen plasma.

The rate of transfusion needs to exceed 1 mL/kg/min, which is approximately equivalent to one unit of packed red blood cells (PRBCs) every 5 minutes in an adult.

Answer 502

A

Hemodynamics - Hypotension, Narrowed Pulse Pressure, Increased LVEDP (Decrease in Coronary Perfusion Pressure)

EKG - Prolonged QT, Narrowed QRS, Flat T waves

Answer 503

A

CPDA-1 anticoagulant allows PRBC and whole blood storage for up to 35 days

Citrate is the anticoagulant (binds calcium necessary for clot formation)
Phosphate is incorporated for cellular function and ATP production
Dextrose is the nutrition source for glycolysis
Adenine is incorporated for ATP production

Answer 504

A

EDTA is an irreversible binder of calcium

Answer 505

A

Minimal Sedation - Normal rersponse to verbal

Moderate sedation - Purposeful rersponse to verbal/tactile

Deep - Purposeful response after repeated/painful

General anesthesia - Unarousable

Answer 506

A

Carbon Dioxide

Answer 507

A

Brown

Answer 508

A

~400L (25% full)

A full E cylinder of nitrous oxide is 8.80 kg and has a pressure of 745 psig, an empty cylinder is 5.90 kg.

Answer 509

A

Grade III: no cords visible, only epiglottis visible.

*Grade IIIa: only epiglottic edge visible (epiglottis** raised).
*Grade IIIb**: downfolded or floppy epiglottis is visible.

Answer 510

A

PaCO2 is always greater than ETCO2 with a gradient of 2-5 mm Hg in spontaneously breathing, nonanesthetized patients

Yes. under anesthesia = 5-10 mm Hg in mechanically ventilated patients.

Ex: ETCO2 is 40, you will have PaCO2 of 45-50 mmHg

Answer 511

A

This is because desflurane is near boiling point at room temperature (73 F), which means an unpredictable amount is in liquid form, while the rest of it may be in gaseous form.

This heated vaporizer reliably converts desflurane to the gaseous form.

Answer 512

A

5 metabolites - but primarily undergoes glucuronide conjugation without any phase I metabolism and, because of this, is less affected by age and renal disease

The main metabolite of lorazepam is inactive and water-soluble, thus is excreted rapidly by the kidneys

Answer 513

A

QTc prolongation (20%)

Headache (11%)

Transient transaminitis (5%)

Constipation (4%)

Answer 514

A

Ondansetron is known to cause QTc prolongation in nearly 20% of patients. However, the prolongation is typically 20-30 msec or less, which is clinically insignificant (though statistically significant)

except in patients with already prolonged QTc intervals or those with additional risk factors for prolonged QTc intervals (e.g. hypokalemia, hypocalcemia, hypothyroidism, history of myocardial infarction, long QT syndrome, and recent use of other medications that prolong the QTc interval).

Answer 515

A

TIVA (Vapor can prolong QTc)

Correct Potassium (Hypo can exacerbate)

Correct Calcium (Hypo can exacerbate)

Get TSH and Free T4 levels (Hypo can exacerbate)

Answer 516

A

HIGH RISK FACTORS + HIGH RISK PROCEDURES ARE REQUIRED

*The high-risk factors are:**
1) Prosthetic heart valves
2) Prior history of infective endocarditis
3) Unrepaired cyanotic congenital heart disease
4) Completely repaired congenital heart defect (the first six months after procedure)
5) Repaired congenital heart disease with residual defect
6) Valvular disease in a transplanted heart

Of note, prophylaxis is NOT required in patients with bicuspid aortic valve, acquired aortic/mitral disease, or hypertrophic cardiomyopathy (HOCM).

The high-risk procedures are:*
1) Dental work – highest risk for infective endocarditis in procedures that involve gingival tissue manipulation or perforation of the oral mucosa. For example, tooth extractions, or drainage of a dental abscess. However, routine dental cleaning is not a high-risk procedure that requires prophylaxis.
2) Respiratory tract procedures that warrant prophylaxis are those involving incision/biopsy of the respiratory tract mucosa. This includes tonsillectomy, adenoidectomy, and bronchoscopy with biopsy.
3) Skin or musculoskeletal tissue procedures

Answer 517

A

The current prophylactic regimen is:

Amoxicillin

OR

Ampicillin 2 g given 1 hour before the procedure.

Answer 518

A

Those who are allergic to penicillin can be given clindamycin 600 mg.

OR

Azithromycin 500mg or ceftriaxone 1g

Answer 519

A

The order of non-depolarizing muscle relaxant potentiation is desflurane > sevoflurane > isoflurane > halothane > TIVA (e.g. propofol).

Answer 520

A

Increasing the heart rate increases inotropy through the Treppe (or Bowditch) effect?

Answer 521

A

Additionally, administration should not exceed 10mg/min because of the risk of vancomycin infusion syndrome (i.e. “red man syndrome”).

Vancomycin infusion syndrome is characterized by hypotension, tachycardia, generalized pruritus, and red rash.

Answer 522

A

Methylene blue (1-2 mg/kg) is the primary pharmacologic treatment of methemoglobinemia.

Answer 523

A

Methylene blue is a monoamine oxidase inhibitor. Doses > 5mg/kg in the setting of selective serotonin reuptake inhibitor use may precipitate serotonin crisis.

For this reason, indigo carmine may be preferred for use in detecting ureteral injury.

Answer 524

A

Patients with G6PD-deficiency are unable to generate NADPH sufficiently and therefore methylene blue is not only ineffective, but paradoxically serves as an oxidant stress leading to hemolysis.

Ascorbic acid (vitamin C) can serve as an electron donor (antioxidant), and is the treatment of choice of methemoglobinemia in the setting of G6PD-deficiency.

Answer 525

A

Collapse <50% suggests volume overload

Caval Index >50% suggests fluid responsiveness

Answer 526

A

IVC <1.5 cm suggests volume depletion

IVC >2.5 cm suggests volume overload

Answer 527

A

At high altitudes, the partial pressure of desflurane will decrease in proportion to the reduction in atmospheric pressure as it correlates to the calibration pressure, usually 760 mmHg (1 atm)

OR

Another way of saying this is gas delivered will be inversely proportional to altitude

Answer 528

A

Anatomic dead space is equal to the volume in the portions of the airways not involved in gas exchange (i.e. oronasopharynx, trachea, bronchi, and most of the bronchioles).

Alveolar dead space is the volume in the alveoli that is not being perfused and not involved in gas exchange.

Physiological Dead Space = The sum of alveolar and anatomic dead space

Answer 529

A

Approximately 2 mL/kg in the adult patient.

Also, remember that the dead space to tidal volume ratio (Vd/Vt) is usually 33% since tidal volume is approximately 5-7 mL/kg.

Answer 530

A

Dead space is increased in the upright position relative to the supine position.

This occurs due to an increase in alveolar dead space since the apices of the lungs are essentially non-perfused in the upright position due to the effects of gravity on blood flow distribution.

Answer 531

A

Positive pressure ventilation (PPV) increases alveolar dead space and can worsen ventilation to perfusion matching.

A spontaneously breathing patient with healthy lungs has a dead space to alveolar ventilation ratio of 1:2 whereas the ratio will be 1:1 with PPV.

Positive intrathoracic pressure can decrease cardiac output and therefore pulmonary perfusion due to decreased venous return to the right heart.

Answer 532

A

Large quantities of natural licorice will induce hyperaldosterone-like effects including:

hypokalemia

hypertension

hypernatremia

Fluid overload

metabolic alkalosis

Answer 533

A

Mixing propofol with lidocaine has been shown to decrease the stability of the propofol emulsion and may cause pulmonary embolism.

The FDA recommends against mixing propofol with any other therapeutic medications prior to administration.

When 40 mg of lidocaine was added, droplets of greater than 5 mcm were detected at 30 minutes. The theoretic human risk of embolism occurs at droplet sizes greater than 5 mcm

Answer 534

A

The second gas effect occurs when nitrous oxide and a volatile anesthetic are used concurrently.

Uptake of nitrous oxide is significant because of the high concentration used (the concentration effect).

When a significant amount of nitrous oxide is removed from the alveoli into the blood the relative alveolar concentration of the volatile agent being used increases.

This increase speeds up the anesthetic onset for the volatile agent, which is the second gas effect.

Answer 535

A

The concentration effect occurs when a high concentration of anesthetic can be used. Currently the only anesthetic in clinical use in which the concentration effect can be demonstrated is nitrous oxide.

This effect explains why nitrous oxide has a more rapid onset than desflurane.

Answer 536

A

Measure of lipophilicity.

The oil:gas coefficient is related to anesthetic potency and minimum alveolar concentration (MAC).

The higher the oil:gas coefficient the lower the MAC.

Isoflurane has an oil:gas coefficient of 99 and a MAC of about 1.

Whereas desflurane has an oil:gas coefficient of 19 and a MAC of about 6.

Answer 537

A

Solubility of commonly used anesthetics is:

desflurane > nitrous oxide > sevoflurane > isoflurane from least soluble to most soluble.

(Note des is greater than nitrous)

Answer 538

A

Medial Nerve

Answer 539

A

Unopposed parasympathetic stimulation following spinal anesthesia causes increased gastrointestinal secretions.

Answer 540

A

After single lung transplantation, the capnogram would be unique for each lung, if they were to be separated.

The transplanted lung, assuming it is healthy, would produce an essentially normal pattern of exhalation (see Figure 1).

The native lung, however, is still diseased and will show an obstructive appearance (slow, blunted upstroke, phase 2–3) and no plateau of exhalation (phase 3-4) is reached.

Combined, this causes a “double peak” appearance, as in Figure 2. The first peak is from the normal (transplanted) lung, while the second peak of the tracing represents exhalation from the native, diseased lung.

Answer 541

A

Replace the Exhausted CO2 absorbent or increase the flows

Capnogram of incompetent inspiratory valve. The expiratory alveolar plateau is extended due to inspiration of CO2-rich gas at the beginning of inspiration. The blue arrows above indicate where inspiration actually began in the patient. The inspiratory phase is shortened, has a blunted downstroke, and the CO2 nadir may or may not reach zero.

Answer 542

A

Incompentent Expiratory Valve

Answer 543

A

Bleeding

Answer 544

A

Infection resulting from improper storage is the most common risk associated with autologous blood transfusion.

Answer 545

A

Does not place the recipient at risk of immune-mediated reactions
Reduce*** the incidence of complications associated with allogeneic donor blood, such as ***hemolytic and non-hemolytic (febrile, urticarial, and post-transfusion purpura) reactions resulting from donor proteins triggering an immune-mediated reaction in the recipient

Answer 546

A

Physostigmine is an anticholinesterase with a tertiary amine structure that can be used as a treatment for central anticholinergic syndrome.

Reversal of toxic anticholinergic effects: Note: When administering by IV injection, administer no more rapidly than 1 mg/minute to prevent bradycardia, respiratory distress, and seizures from too rapid administration. Slower administration (ie, over no less than 5 minutes) may be preferable (Howland 2019).

IM, IV: Initial: 0.5 to 2 mg; may repeat every 10 to 30 minutes until response occurs. Subsequent doses may be required to manage life-threatening anticholinergic effects (Krenzelok 2010).

Answer 547

A

This is typically done for hemodynamically unstable patients, such as during massive hemorrhage or trauma.

Scopolamine IV may also be given preoperatively to reduce the risk of awareness in selected populations.

Sedation, amnesia: IM, IV, SubQ: 0.3 to 0.6 mg 3 to 4 times/day

Answer 548

A

The Poiseuille Law states that:

Q = ΔP(π * radius4) / (8 * viscosity * length)

Where: Q = flow, Δ = change in, P = pressure, π = 3.14159… (the mathematical constant).

Answer 549

A

Nitroprusside is metabolized to cyanide ions and toxicity can occur following lengthy infusions. The three major mechanisms for nitroprusside toxicity are

1) Cyanide ions bind to cytochrome c oxidase and inhibit cellular aerobic respiration.
2) Formation of cyanmethemoglobin which is unable to carry oxygen.
3) Thiocyanate production which causes CNS-related effects.

Answer 550

A

The internal branch of the superior laryngeal nerve (SLN) provides sensation to the entire larynx above the glottis. Laryngospasm can result from stimulation of this nerve.

Answer 551

A

Nervous System

Decreased gray/white matter
Decreased neurotransmitters (acetylcholine, dopamine)
Decreased epidural space
Decreased CSF volume
Increased permeability of dura mater

Answer 552

A

Cardiovascular System

Decreased ventricular compliance (dependent on atrial kick)
Decreased beta-receptor responsiveness (decreases maximal heart rate)
Increased sympathetic nervous system activity
Increased stiffness of large arteries (Hypertension common)

- Increased afterload

Decreased diastolic dysfunction

LVEDP increases (due to decreased diastolic dysfunction)

Answer 553

A

*Respiratory System**
Decreased vital capacity
Increased residual volume
Increased closing capacity
Increased anatomic dead space
Increased lung compliance
Increased pulmonary vascular resistance

Answer 554

A

Decreases

Answer 555

A

AC power source

Interference from an alternating current (AC) source produces a thick ECG tracing which alternates up-and-down 60 times a second (60 hertz) in the United States, see above.

Interference can occur if an AC power cord is lying across the ECG cable or the ECG monitor. It can also occur if the ECG cable or monitor is too close to an AC source.

Answer 556

A

A right-to-left intracardiac shunt slows the rate of inhalational induction of anesthesia since the shunted blood is not involved in gas exchange within the alveoli.

Conversely, a right-to-left shunt speeds the rate of intravenous induction because a portion of the drug bypasses the lungs, directly enters the left side of the heart and is quickly delivered to brain tissue. Note, if you feel these sentences contradict each other please re-read carefully.

Answer 557

A

Decreased CO = Faster induction

allows for increased partial pressures of anesthetic gases within the alveoli, resulting in a faster rate of induction. The alveolar partial pressures of the anesthetic remain elevated since less blood can interface with the same number of alveoli filled with a volatile agent. The slow diffusion of a volatile agent into the blood results in faster delivery of the agent to brain tissue. This is because a greater volume of blood is saturated with volatile agent per liter of cardiac output delivered per unit of time.

Higher CO = Slower induction

more blood is involved in gas exchange resulting in increased uptake of anesthetic gas and a larger dilutional effect. This decreases the partial pressure of gas within the alveoli, reduces delivery to the brain, and slows the rate of induction.

Answer 558

A

The effect of cardiac output on the rate of induction is particularly accentuated in agents that have a higher blood:gas partition coefficient. This partition coefficient is a distribution ratio describing how the volatile anesthetic distributes itself between liquid (blood) phase and the gaseous phase (in the alveoli) when the partial pressures are identical in both phases.

If the blood:gas partition coefficient is > 1, then more drug is dissolved in the blood (higher solubility, such as isoflurane or halothane).

If the blood:gas partition coefficient is < 1, more drug exists in the gaseous state and not dissolved in blood (lower solubility, such as desflurane or nitrous oxide). These relationships hold as long as the partial pressures are equal in both phases.

Blood:gas partition coefficients of key anesthetic gases

Desflurane 0.42

Nitrous Oxide 0.46

Sevoflurane 0.69

Isoflurane 1.46

Halothane 2.54

The rate of a rise of FA:FI as a function of cardiac output. A decrease in cardiac output (e.g. from 10 L/min to 2.5 L/min) will increase the alveolar partial pressures of the volatile agent by slowing uptake and speeding the rise of FA:FI ratio. This effect is less pronounced in the insoluble volatile anesthetics (e.g. desflurane) and more pronounced in the soluble ones (e.g. isoflurane). The effect of changing cardiac output is less pronounced for the more insoluble anesthetics.

Answer 559

A

New generation carbon dioxide absorbents do not contain strong bases and as a result, are much less likely to react with volatile anesthetics and generate carbon monoxide.

Answer 560

A

Fresh frozen plasma should be avoided in the following situations:

Use to correct mildly elevated INR (< 1.8) without signs of bleeding
Use to correct a vitamin K deficiency that could be corrected with vitamin K
Use as a primary volume expander (absolute contraindication)
Use to correct a factor deficiency when recombinant factor replacement is available

Answer 561

A

Low dosing: 0.5 to 3 mcg/kg/min

At lower concentrations, dopamine primarily acts on the D-1 dopamine receptors to produce vasodilation of the renal, mesenteric, and coronary vasculature.

The main result is an increase in the glomerular filtration rate and renal blood flow (RBF)

Furthermore, low dose dopamine will result in sodium excretion which will increase urine output.

Answer 562

A

Moderate dosing: 3 to 10 mcg/kg/min

Beta-1 Receptors

Contractility increases (Ionotropy)
Minimal change in HR anad SVR
Increase in splanchnic and renal blood flow

Answer 563

A

High dosing: >10 mcg/kg/min

Higher doses will stimulate the Alpha 1 and beta-1 receptors to increase release of norepinephrine from sympathetic nerve terminals.

The end result is an increase in heart rate, systolic blood pressure, and pulse pressure.

Diastolic blood pressure is minimally affected however pulmonary vascular resistance may increase.

At the highest doses, dopamine administration will stimulate alpha-1 receptors which results in peripheral vasoconstriction.

Answer 564

A

Cyclopentolate is an anticholinergic drug often used during ocular surgery to induce mydriasis that can lead to CNS toxicity, including convulsions, if absorbed systemically.

Answer 565

A

The area postrema of the brainstem, also known as the chemoreceptor trigger zone, contains dopamine, serotonin, acetylcholine, histamine, and neurokinin type 1 receptors.

Dopamine - Haloperidol

Serotonin - Zofran

Acetylcholine - Diphenhydramine, Scopalamine, other Anti-cholinergics

Histamine - Diphenhydramine

Neurokinin 1 - Aprepitant

Antagonism of these receptors can help treat and prevent nausea. However, any medication leading to central antagonism of dopamine receptors can potentially cause EPS.

Answer 566

A

Although routinely used to decrease risk for aspiration, recent evidence suggests cricoid pressure may actually increase the risk for reflux in anesthetized patients.

Cricoid pressure decreases LES tone without influencing gastric pressure.

This leads to a decreased barrier pressure and therefore potentially increases the risk of aspiration.

The clinical significance of this, however, has not been determined.

Opponents of cricoid pressure affirm that succinylcholine increases LES tone, making the need for cricoid pressure during rapid sequence induction (RSI) questionable.

Cricoid pressure continues, however, to be the standard of care during RSI.

Answer 567

A

The duration of action of midazolam (half-life 1.7-2.6 hours) exceeds that of flumazenil (half-life 0.7-1.3 hours). This makes recrudescence of benzodiazepine-induced somnolence after metabolism of flumazenil likely in this context.

Approximately half

Answer 568

A

Efficacy is the maximum effect of a drug. It does not depend on dose.

Potency is the relative dose required to achieve a given effect and is related to receptor affinity and is dose dependent

Answer 569

A

The potency of a partial agonist may be higher than that of a full agonist.

The efficacy of a partial agonist cannot be higher than that of a full agonist.

Answer 570

A

Antacids such as 0.3 M sodium bicitra can be given 15-30 minutes prior to induction to increase gastric pH, however, they will increase gastric volume which is not of particular concern as the real damage to the lungs with aspiration will be caused by the acidity of the fluid, not necessarily the volume.

Answer 571

A

decrease the secretion of gastric acid, resulting in a reduction in gastric volume and an increase in gastric pH. They can be used for aspiration prophylaxis in at-risk patients.

H2 blockers must be given approximately 30 minutes prior to induction of anesthesia to have effectiveness and they last for approximately 9-12 hours (except cimetidine which only lasts 3-4 hours and has multiple side effects such as P450 inhibition, hypotension, arrhythmias and CNS depression). They have no effect on gastric fluid already present and do not speed clearance of gastric fluid already present.

Answer 572

A

Metoclopramide is a gastrokinetic drug that relaxes the pylorus and duodenum and increases upper GI motility to increase clearance of gastric fluid, however, it does not alter gastric fluid pH.

Metoclopramide also increases lower esophageal sphincter tone because of cholinomimetic actions and can have extrapyramidal side effects as it is a D2 receptor blocker.

Answer 573

A

Since plasma cannot be washed of IgA, it must come from a deficient donor.

Answer 574

A

The complement system is activated in a hemolytic transfusion reaction that typically occurs when ABO incompatible blood is given.

A hemolytic transfusion reaction will result in the destruction of donor red blood cells and the release of hemoglobin in the blood.

Free circulating hemoglobin can precipitate in the kidneys resulting in kidney failure.

The antibody mediated immune response results in the release of bradykinin, serotonin, and histamine leading to flushing, bronchospasm, and hypotension.

In addition, 30-50% may develop disseminated intravascular coagulation (DIC).

If the patient is under general anesthesia, initial signs include hypotension and hemoglobinuria.

Answer 575

A

Nonhemolytic

Caused by cytokines and the release of intracellular contents in leukocytes.

In addition to fever, patients may have chills, myalgias, headache, and non-productive cough.

The use of leukoreduced blood minimizes this reaction.

Answer 576

A

Graft versus host disease may occur in immunocompromised patients when viable donor lymphocytes become engrafted, proliferate, and establish an immune response against the recipient. Other patients at risk are individuals receiving blood from a close relative.

The host does not recognize the lymphocytes as foreign while the donor cells recognize the host as foreign.

Measure = Blood given to immunocompromised patients and blood from first degree relatives should be irradiated to inactivate donor lymphocytes.

Answer 577

A

Intubating doses of neuromuscular blocking drugs are increased in cirrhosis because of the increase in volume of distribution.

Maintenance doses of hepatically metabolized and/or cleared drugs should be reduced and neuromuscular function carefully monitored as duration of action is prolonged.

**Paradox**

Neuromuscular blocking agents are highly water-soluble due to quaternary amine structures and thus an increase in body water, such as with cirrhosis, CHF, or renal failure, results in decreased plasma concentration of neuromuscular blockers requiring an increase in intubating dose.

It is important to remember, however, that clearance of drugs dependent on hepatic metabolism is reduced and therefore they will have a prolonged duration of action. Rocuronium, vecuronium, and pancuronium will all have increased duration of action secondary to impaired hepatic metabolism (caveat: rocuronium is not metabolized but is cleared by the liver in the bile) and therefore maintenance dosing should be reduced and neuromuscular monitoring carefully followed.

Answer 578

A

A breakdown product, laudanosine, is cleared by the liver but levels produced are insignificant clinically.

Laudanosine decreases the seizure threshold, and thus it can induce seizures if present at sufficient threshold concentrations; however such concentrations are unlikely to be produced consequent to chemodegradable metabolism of clinically administered doses of cisatracurium or atracurium..

Laudanosine is a benzyltetrahydroisoquinoline alkaloid

Answer 579

A

apnea time is increased from 3 minutes to 9 minutes.

Answer 580

A

1) Anesthetic potency = lipid solubility
- Higher solubility enhances diffusion through nerve sheaths/membranes.
- Less lipid solubility results in less potent agents (Less diffusion)
(ex: procaine is the least lipid-soluble and least potent LA, bupivacaine is highly lipid soluble and the most potent.

Answer 581

A

2) Time to onset/Onset of action = pKa = dissociation constant: determines the pH at which a drug’s ionized (charged) and unionized (uncharged) forms are in equal concentrations.

This determines the amount of drug in the unionized form. This is why many local anesthetics do not work in acidic areas such as abscesses.

pKa Lidocaine = 7.9

pKa Bupivicaine = 8.1

pKa Chloroprocaine = 9 (Paradox due to volume)

Answer 582

A

Duration of action = protein binding.

Agents that are highly protein bound will remain bound for longer, increasing the duration of action.
Duration of action is also influenced by peripheral vascular effects (such as use of vasoconstrictors)
* Why we add epinephrine to our local anesthetics*

Answer 583

A

ICEBALLS

Location of injection = some areas of the body will have more local anesthetic absorbed. Mnemonic: BICEPSS - Intravenous (Blood) > Intercostal > Caudal > Epidural > brachial Plexus > Axillary > (lower lumbar) Sciatic > Subcutaneous

Answer 584

A

Procaine

7 mg/kg

15-60 minutes

Answer 585

A

Chloroprocaine

Max = **11 - 14 mg/kg** (Without vs. with epinephrine)
Duration = **15-30 minutes**

Answer 586

A

*30-60** without epi
*120-360** with epi

Answer 587

A

mepivacaine

Max = 7 mg/kg

Duration:

45-90 without epi
120-360 with epi

Answer 588

A

Bupivacaine

Max dose

5 (not to exceed 175mg or 70cc)
5 (not to exceed 225mg or 90cc)

Duration

120-140 without epi

180-240 with epi

Answer 589

A

Factors affecting the height of an intrathecal block include:

Patient position
Baricity of anesthetic
Dose of local anesthetic

Answer 590

A

Bradycardia following spinal anesthetic injection is more common in patients with:

1. High baseline vagal tone

2. Anesthetic levels above T5

3. Associated with decreased cardiac preload (i.e. reverse Bainbridge reflex).

Answer 591

A

Sympathectomy of cardioaccelatory fibers (T1 - T4)
Drop in preload and SVR (decreased stretch on myocardium which will result in “reversed bainbridge reflex”)
High Baseline vagal tone (Young atheletes, vasovagal syndromes or autonomic nerve pathology)
Decreased mechanoreceptor stretch can induce the Bezold-Jarisch reflex with increased parasympathetic output, contributing to bradycardia.

Normally, the carotid sinus baroreceptor response to hypotension (increased heart rate and contractility) dominates, but in the setting of an acute drop in ventricular preload (e.g. spinal anesthetic or nitrate use), the Bezold-Jarisch reflex may occur before the carotid sinus reflex.

Answer 592

A

Thromboelastography (TEG) is both a quantitative and graphic evaluation of clotting function. Typical management is:
R value

K value

Alpha Angle

MA value

Answer 593

A

MA value decreased -> platelets.

Answer 594

A

Cryoprecipitate

Answer 595

A

Anti-fibrinolytics (TXA)

Answer 596

A

Reaction time (R) is from time zero to initial clot formation, defined as a width (amplitude) of 2 mm. Normal range is 1-3 minutes.

Answer 597

A

Coagulation time (K) measures speed of clot formation and strengthening. It is equal to the time from amplitude of 2 mm to 20 mm and relies on fibrinogen.

Treatment = Cryoprecipitate

Answer 598

A

Maximum amplitude (MA), measures the strength of the fully formed clot. It is the maximal width of the TEG. This reflects clot strength as determined by platelet number and function (primarily) as well as fibrin cross linking. Normal is 50-60 mm.

Answer 599

A

Alpha-angle is the speed of clot formation, and is represented by the angle between baseline and a line tangential to the TEG at 2 mm amplitude. Like the K value, this relies on _fi_brinogen. Normal alpha angle is 45-55 degrees.

Answer 600

A

Echothiophate is an anticholinesterase used to treat refractory glaucoma by causing miosis. Systemic absorption can cause up to a 95% decrease in plasma butyrylcholinesterase (pseudocholinesterase) function. Patients using echothiophate eye drops have demonstrated prolonged neuromuscular block after succinylcholine administration. It may take up to 4-6 weeks after discontinuation of the drug for normal butyrylcholinesterase activity to return.

Answer 601

A

Renin secretion can be caused by 3 different mechanisms:

Decrease in serum NaCl concentration sensed by the kidneys
Decrease in blood pressure sensed by kidney baroreceptors
Activation of renal B1 receptors by norepinephrine.

Answer 602

A

Increase in blood pressure caused by an increase in systemic vascular resistance

Activates the angiotensin1 (AT1) receptors on vascular smooth muscle cells, causing constriction of the arterioles

Augments the sympathetic nervous system by inhibiting norepinephrine reuptake into nerve terminals. It also stimulates the release of catecholamines from the adrenal medulla.

Centrally mediated increased thirst and enhances the release of vasopressin. These effects are almost immediate, but are not long-lasting.

Stimulates remodeling of the cardiovascular system, causing hypertrophy of cardiac cells and increased collagen deposition

Decrease in the urinary excretion of both sodium and water.

Stimulates the adrenal cortex to synthesize and release aldosterone.

Aldosterone also acts on the kidneys to decrease the urinary excretion of sodium and water. This ultimately leads to an increase in blood volume and therefore blood pressure.

Answer 603

A

Pros
Use of opioids as adjuncts for neuraxial anesthesia and analgesia can significantly enhance block quality, density, and duration of analgesia.

Cons

However, this comes at the price of an increased risk of side effects including sedation, respiratory depression, pruritus, and nausea/vomiting, compared to local anesthetics alone.

Answer 604

A

The ASA recommends a longer period of monitoring for respiratory depression following a single neuraxial dose of morphine compared to fentanyl.

For lipophilic opioids: continual monitoring for at least 20 minutes following administration and then at least hourly monitoring for the next two hours.

For hydrophilic opioids: at least hourly monitoring for the first 12 hours and then monitoring at least every two hours for the next 12 hours.

Answer 605

A

A mnemonic to help recall light absorption by wavelength is SeXy DARLing: at SiX hundred wavelength, Deoxyhemoglobin Absorbs Red Light.

Answer 606

A

Red light at 660 nm and infrared light at 940 nm (some manufacturers use 905, 910, or 920 nm) is pulsed through the tissue. A ratio of the absorbance of red to infrared light is calculated and that calculated number is translated to the oxygen saturation reading.

At red wavelengths, deoxyhemoglobin absorbs more light than oxyhemoglobin

At infrared wavelengths, oxyhemoglobin absorbs more.

Answer 607

A

The difference in blood pressure at 2 different sites equals the height difference in cm multiplied times the conversion factor 0.74.

Ex: height difference of 22 cm, equaling 16

A mnemonic to help remember which comes first (pressure or height) is “pH” or “pH 15 20”, where a pressure of 15 mmHg correlates to a height of 20 cm.

Answer 608

A

Several risks for MMR have been proposed and include:

Inadequate dose of succinylcholine
Inadequate time for onset
Side effect of other induction medications (etomidate, high dose synthetic opioids)
Temporomandibular joint dysfunction
Duchenne muscular dystrophy
Myotonia congenita, and possibly other muscle disorders.

Answer 609

A

Fresh gas flow (FGF) must be greater than or equal to 1-2 times minute ventilation in the Mapleson D semi-open breathing system to prevent rebreathing during controlled ventilation.

The FGF during spontaneous ventilation must be equal to 2-3 times minute ventilation in the Mapleson D, E, and F circuits.

Answer 610

A

The advantages of a Bain circuit (coaxial version of a Mapleson D system) include:

(1) conservation of moisture due to partial rebreathing
(2) warming of fresh gas inflow by surrounding expiratory gas
(3) scavenging waste is easier from the APL valve
(4) advantageous when access to the patient is limited.

Answer 611

A

Most drugs occurs via two processes, phase I and phase II metabolism.

Phase I includes oxidative and reductive reactions including hydrolytic reactions and those catalyzed by the hepatic cytochrome P450 enzymes

Phase II reactions involve conjugation of the drug or its metabolite(s) with a substrate such as glucuronic acid. Once a drug is metabolized, it is much more efficiently eliminated from the body.

Answer 612

A

The patient’s circulatory function must be continually monitored via three mechanisms.

First, continuous ECG must be used from the beginning of anesthesia until preparing to leave the anesthetizing location.
Second, arterial blood pressure and heart rate must be determined and evaluated at least every five minutes.
Finally, pulse monitoring must be continually evaluated such as via pulse palpation, heart sound auscultation, intraarterial pressure monitoring, and/or pulse plethysmography or oximetry.

Answer 613

A

In all anesthetics in which “clinically significant changes in body temperature are intended, anticipated, or suspected” temperature must be monitored.

Answer 614

A

Intracellular volume (ICV) - The ICV contains two-thirds of TBW and represents 40% of total body weight.

Extracellular volume (ECV). The ECV contains one-third of TBW and represents 20% of total body weight.

Subdivided into plasma volume and interstitial fluid volume.

Plasma volume comprises 20-25% of the ECV and represents 4% of total body weight.

Interstitial fluid volume comprises 75-80% of the ECV and represents 16% of total body weight.

Answer 615

A

Bradycardia may occur in patients treated with sugammadex.

The incidence is approximately 1% with 2 mg/kg and 4 mg/kg doses, and 5% with 16 mg/kg doses.

Answer 616

A

Intrapulmonary shunt reduces the speed of inhalational induction.

Answer 617

A

When perfusion is affected (reduced cardiac output, pulmonary embolism), the speed of induction of inhalational agents is increased. The impact is more significant with soluble agents such as isoflurane. The rise of FA/FI is steeper with lower perfusion of the lungs.

When ventilation is affected (intrapulmonary shunt), the speed of induction of inhalational agents is decreased. This occurs to a greater degree with insoluble agents (desflurane, sevoflurane). The rise of FA/FI is less steep.

Answer 618

A

*The list of patients who should receive prophylaxis is below:**
Patients with a prosthetic cardiac valve
Patients who have history of infective endocarditis
Patients with unrepaired cyanotic congenital heart disease (including palliative shunts/conduits)
Patients with congenital heart defects which were repaired with prosthetic material within 6 months of the procedure
Patients with repaired congenital heart disease with residual defects at the site, or adjacent to the site, of a prosthetic patch or device
Cardiac transplantation recipients who develop cardiac valvulopathy (substantial leaflet pathology and regurgitation)
*Of note, prophylaxis only applies to certain surgical procedures:**
Dental* procedures that involve *manipulation of gingival tissue or the periapical region of teeth or perforation of the oral mucosa
Invasive respiratory tract* procedures that involve *incision or biopsy of the respiratory mucosa (e.g. tonsillectomy, adenoidectomy)
Infected skin, skin structure, or musculoskeletal tissue

Answer 619

A

The preferred prophylactic regimen is Amoxicillin 2 g given as a one time oral dose 30-60 min before the procedure.

Answer 620

A

This negative force can be upwards of -50 to -100 cm H2O of pressure.

The negative pressure causes a significant increase in preload, thereby increasing pulmonary blood volume. There is also a significant increase in left ventricular afterload, which causes a decreased cardiac output.

The increase in pulmonary blood volume along with a decrease in cardiac output will increase the pulmonary transudative pressures. With all this occurring, pulmonary vascular resistance increases causing a shift of the intraventricular septum. The ventricular septal shift to the left causes a left ventricular diastolic dysfunction, which further increases pulmonary hydrostatic pressures.

Answer 621

A

Active cardiac conditions mandate further preoperative evaluation and treatment.

*Active Cardiac Conditions:**
1) Unstable coronary syndromes

(UA, MI)
2) Decompensated heart failure

(NYHA class III or IV, severe angina)
3) *_Significant arrhythmias_*

(high-grade AV block, Mobitz type II AV block, third-degree AV block, symptomatic ventricular arrhythmias, supraventricular arrhythmias (including atrial fibrillation) with uncontrolled ventricular rate > 100 bpm at rest, symptomatic bradycardia, and newly recognized ventricular tachycardia)
4) Severe valvular disease
Severe aortic stenosis (mean pressure gradient > 40 mmHg, aortic valve < 1.0 cm^2, or symptomatic) and symptomatic mitral stenosis (progressive dyspnea on exertion, exertional presyncope, or heart failure).

Answer 622

A

*Revised Cardiac Risk Index Variables:**
1) History of ischemic heart disease
2) History of congestive heart failure
3) History of cerebrovascular disease
4) Insulin therapy for diabetes
5) Preoperative serum creatinine > 2.0 mg/dL
6) High-risk type of surgery

Answer 623

A

Criteria:
1) Acute lung injury (ALI)
- Acute onset
- Hypoxemia (PaO2:FiO2 ≤ 300 mm Hg or SpO2 < 90%
on room air, or other clinical evidence of hypoxemia
- Bilateral infiltrates on frontal chest radiograph
- No evidence of left atrial hypertension as the sole
explanation for the clinical findings
2) No pre-existing ALI before transfusion
3) Onset during or within 6 hours of transfusion
4) No temporal relationship to an alternative
risk factor for ALI

Answer 624

A

New onset or exacerbation of three or more of the following within 6 hours of transfusion:

Acute respiratory distress (dyspnea, cough, orthopnea) Symptoms
Increased brain natriuretic peptide (BNP) Labs
Increased central venous pressure (CVP) Hemodynamics
Evidence of left heart failure Clinical diganosis / Echo
Evidence of positive fluid balance I/O balance
Radiographic evidence of pulmonary edema Imaging

Answer 625

A

Y axis = % Hemoglobin Saturated (SaO2)

X axis = PaO2

Answer 626

A

Excluding patients less than one year of age, the MAC of each of the potent anesthetic gases declines with age.

There is a linear model that describes the change in MAC of approximately 6% per decade, a 22% decrease in MAC from age 40 to age 80, and a 27% decrease in MAC from age 1 to age 40 years.

Answer 627

A

MAC rises at one month of age, peaks at approximately 6 months of age, and regresses back to normal at 1 year of age.

Sevoflurane demonstrates a much higher increase in MAC compared to the slight increase with desflurane and isoflurane.

The MAC of sevoflurane is often up to 2.5-3% higher in patients 1 month to 1-year-old.

Answer 628

A

Increases MAC Requirements

Answer 629

A

Tetanus acts by preventing neurotransmitter release (glycine and GABA) from inhibitory neurons in the spinal cord.

The lack of inhibition causes increased muscle contractions to the point of tetanus.

Answer 630

A

Botulism toxin has a similar mechanism of preventing neurotransmitter release (acetylcholine), but botulism affects the alpha motor neuron causing flaccid paralysis.

Answer 631

A

The classic “carcinoid triad” consists of flushing, diarrhea, and right-sided cardiac involvement.

It is caused by tumor release of vasoactive amines* (e.g. serotonin, norepinephrine, histamine, and dopamine), *polypeptides* (e.g. bradykinin, somatostatin, vasoactive intestinal peptide, and glucagon), and *prostaglandins.

The cardiac involvement is generally limited to only the right side of the heart since, as discussed above, most of the vasoactive hormones are metabolized while in the pulmonary circulation before returning to the left side of the heart.

Answer 632

A

KEY = Acute vs. Chronic CCB usage

Calcium channel blockers can augment depolarizing and nondepolarizing muscle relaxants, particularly when the two drugs are administered concurrently to CCB-naïve patients (Calcium channel blockers given acutely)

Consider the careful titration of NBDs in this setting. In patients taking chronic CCBs, the augmentation effect is clinically insignificant.

Answer 633

A

Cytochrome p450 is involved in phase I metabolism by oxidizing many drugs.

Answer 634

A

The MABL of a patient = [EBV * (starting Hct - target Hct)] / (starting Hct).

Age Group. EBV (mL/kg)

Premature infant 90-105

Full term newborn 80-90

Infant (3 months - 1 year) 70-80

Child 1-12 years 70-75

Adult Female 60-65

Adult Male 65-70

Answer 635

A

Methylparaben is the methyl ester of para-hydroxybenzoic acid, which is structurally similar to para-aminobenzoic acid (PABA), differing only in having a hydroxyl group vs amino group in the para position.

Thus, cross-sensitivity between these compounds can occur.

Answer 636

A

Sulfites such as sodium metabisulfite are added as antioxidants for the catecholamine content.

Lidocaine vials with epinephrine will typically contain metabisulfite, which may also elicit allergic responses.

Answer 637

A

pH: increases 0.017 per °C decrease

PaCO2: decreases* 2 mm Hg per °C *decrease

PaO2: decreases* 5 mm Hg per °C *decrease

Blood pH and the solubilities of gases in blood are inversely related to temperature while the partial pressures of gases are directly related to temperature.

Answer 638

A

Class: Antihistamine (H1 antagonist used as an antiemetic)

Dosing: Nausea and vomiting: IV, rectal: 12.5 to 25 mg every 4 to 6 hours, as needed

Administration: Through non-patient IV can cause tissue necrosis

IV use should be avoided when possible since severe tissue damage has occurred with IV administration; in selected patients, promethazine has been diluted and infused at a maximum rate of 25 mg/minute.

To minimize phlebitis, consider administering over 10 to 15 minutes, limiting initial dose to 1/4 or 1/2 the usual dose (eg, in adults 6.25 to 12.5 mg), further diluting the 25 mg/mL strength in 10 to 20 mL NS, and administering through a large bore vein (not hand or wrist) (Reynolds 2014) or via a running IV line at port farthest from patient’s vein

Answer 639

A

A mnemonic to help is “pH 15 20” to remember the pressure of 15 mm Hg is equal to a change in height of 20 cm.

Answer 640

A

Nerve conduction studies are beneficial in evaluating both motor and sensory deficits.

Evaluate between existing subclinical polyneuropathy and some distinction of axon loss and demyelination

Electromyography can help determine the timing of the nerve injury.

Answer 641

A

Male
Thin or Obese (BMI > 38)
Prolonged bed rest
Genetic predispositon (Bilateral neuropathy found)

Presents 48 hours after surgery

Answer 642

A

Sensory = Resolve in 5 days (self limiting)

Motor = Neurology consult

Always seek neurologic consultation. Sensory injuries usually resolve, whereas motor injuries are more severe and mandate EMG (can help determine if it was present preoperatively, as denervation signs take ~ 3 weeks to develop).

Reversible motor nerve injuries usually take 3-12 months to recover and require physical therapy to prevent atrophy and contractures in the interim

Answer 643

A

Local anesthetics with a pKa closer to a physiologic pH will have more drug in the nonionized form, and therefore more drug available for use.

pH < pKa = ionized.

pH = pKa, 50% of the molecules will be ionized and 50% will be unionized.

pH > pKa = Non-ionized

Answer 644

A

Cerebral blood flow is:

Inversely related to PaO2 when less than 50 mm Hg while remaining unchanged with PaO2 > 50 mmHg

Directly related to body temperature

PaCO2 (within normal physiologic ranges)

Extremes of MAPs (< 50 or >150 mm Hg) and remains unchanged within the autoregulatory range of MAPs (50-150 mm Hg)

ICP

Answer 645

A

Differential blockade with local anesthetics results in sympathetic blockade first, followed by pain/sensory blockade, then motor blockade last

Answer 646

A

This is (at least in part) explained by differential susceptibility of nerve fibers to local anesthetics being:

A-delta, A-gamma > lA-alpha, A-beta > C.

Answer 647

A

Compliance = Change in Volume / Change in Pressure

Elastance = Change in Pressure / Change in Volume

Answer 648

A

Remember, Compliance is [Change in Volume] / [Change in Pressure]

calculate static respiratory system compliance:
CS = [Tidal Volume] ÷ (Plateau Pressure – PEEP)

Dynamic = Just replace the plateau pressure with peak pressure during inspiration

Answer 649

A

The gauge pressure will continue to read 745 psig (“full”) until approximately 16% or 253 liters of the nitrous oxide remains.

Answer 650

A

A full E-cylinder of nitrous oxide is approximately 8.80 kg; an empty cylinder is approximately 5.90 kg. At room temperature, one gram of nitrous oxide is equivalent to 0.55 liters of gas at 20 °C. Thus, to calculate the volume of nitrous oxide in an E-cylinder based on weight, the following formula may be used:

Volume remaining (L) = (cylinder weight (g) – 5900 g) x 0.55 L/g

Volume = ( 6.5 - 5.9 ) x 0.55 = 0.33 liters

Answer 651

A

Volume remaining (L) = (gauge pressure (psig) / 745 psig) x 253 L

Volume = (400/745) x 253 liters = 135 Liters

Answer 652

A

Acute onset (within 72 hours)
Bilateral pulmonary infiltrates on chest radiograph
Noncardiogenic pulmonary edema
PaO2/FiO2 ratio of < 300

(The Berlin definition stratifies ARDS into mild, moderate, and severe based on the PaO2/FiO2 ratio of 200-300, 100-200, and < 100 respectively).

Answer 653

A

application of PEEP, conversion to extracorporeal membrane oxygenation (ECMO), use of inhaled nitric oxide, or inverse ratio ventilation.

Oxygen therapy is of limited value* with *large intrapulmonary shunts due to limitation of gas exchange and requires alternative therapies to improve V/Q matching.

Answer 654

A

V/Q

Dead space = Ventilation but no blood flow

Shunt = No ventilation but blood flow

Answer 655

A

Nonanion gap metabolic acidosis (where the anion gap is normal at 8-12 mEq/L) is typically caused by

1. Chloride-containing acid administration

2. Increased HCO3- loss or loss of HCO3- precursors

3. Decreased renal acid excretion

Answer 656

A

Total parenteral nutrition often contains ammonium chloride and metabolism of the amino acids it contains can create HCl.

Together, hyperalimentation can lead to excess Cl- and therefore a nonanion gap acidosis.

Answer 657

A

Increased HCO3- loss is usually via the gastrointestinal (GI) tract or the kidneys.

Causes of increased GI losses include diarrhea, GI fistulas (e.g. pancreatic, biliary, bowel), high ostomy output, or use of bile or phosphorus binding drugs.

Renal losses can be caused by use of carbonic anhydrase inhibitors (e.g. acetazolamide) or type 2 (proximal) renal tubular acidosis (RTA).

Answer 658

A

Decreased acid excretion is due to:

Hypoaldosteronism
Renal causes including acute and/or chronic renal failure or type 1 (distal) RTA.

Answer 659

A

ACCRUED: Acid infusion, Compensation for respiratory alkalosis, Carbonic anhydrase inhibitors, Renal tubular acidosis, Ureteral diversion, Extra alimentation, Diarrhea.

FUSEDCARS: Fistula, Ureteroenterostomy, Saline administration, Endocrine (hyperparathyroidism), Diarrhea, Carbonic anhydrase inhibitors, Ammonium chloride, Renal tubular acidosis, Spironolactone.

Answer 660

A

In patients with a high anion gap metabolic acidosis, HCO3- concentrations decrease as it is consumed buffering a large amount of pathologic anions. This leads to a high anion gap.

Answer 661

A

Glucagon also helps raise blood sugar by three indirect effects.

First, it stimulates lipolysis which produces two substrates for gluconeogenesis: glycerol and free fatty acids.

Second, it inhibits hepatic glycolysis. Since glycolysis consumes glucose to create ATP, stopping this process allows glycolytic intermediates to be shunted into the gluconeogenesis pathway.

Third, glucagon inhibits hepatic glycogen synthesis so that available glucose is released into the bloodstream and not stored within the liver.

Answer 662

A

Depolarizing = Avoid Succinylcholine because patients have denervation or misuse myopathy leading to a higher risk for hyperkalemia

Nondepolarizing agents (Roc, Cis, Vec) can be variable, with a resistance being seen in patients with up-regulation of acetylcholine receptors or a sensitivity in patients with muscle weakness and decreased muscle mass.

Answer 663

A

Key = think of the disorders as conditions that either up-regulate or down-regulate the number of acetylcholine receptors and then infer what use of a specific type of muscle relaxant will do based on the pathophysiology.

Up-regulation of acetylcholine receptors include multiple sclerosis, burns, stroke, spinal cord injury, Guillain-Barre syndrome, prolonged immobility, and muscular dystrophies.

Succ = Contra
Have to use NMBD

Down-regulation of acetylcholine receptors is myasthenia gravis.

Less susceptible to SCh, more susceptible to non-depolarizing NMBDs

Answer 664

A

Burns (24 hours until 1-2 years after)

In patients who have suffered a burn injury, the Ach receptors typically start to increase after 48-72 hours.

In general, succinylcholine should be avoided after 24-48 hours as fatal hyperkalemia may ensue.

Answer 665

A

Risk of reaction increases significantly after 16 days

Answer 666

A

If using NDMR give small doses and monitor neuromuscular function: twitch monitor may not be accurate depending on site (orbicularis occuli underestimates muscle paralysis)

Answer 667

A

Anesthetic Implications:

Sensitive to Succinylcholine

Sensitive to Non-Depolarizing Neuromuscular Blockers

Poor response to anti-cholinesterases = Neostigmine is ineffective for reversal of NDMR

Answer 668

A

Downregulation of ACh Receptors

Prolonged response to depolarizing paralytic (Succinylcholine)

Succinylcholine should be avoided as it is degraded by plasma cholinesterase - may result in prolonged paralysis: neostigmine should be avoided since it will worsen the primary problem

Answer 669

A

The management steps for loss of pipeline pressure are the same as those for pipeline crossover:

1) Open the emergency oxygen cylinder fully (not just the three or four quick turns used for checking).
2) Disconnect the pipeline connection at the wall because something is wrong with the oxygen pipeline.
3) Ventilate by hand with the anesthesia breathing circuit, rather than with the mechanical ventilator (which may use cylinder oxygen for the driving gas if the pipeline is unavailable).

Answer 670

A

Decreased 2, 3-DPG concentration shifts the dissociation curve to the left and decreases oxygen unloading to the tissues.

2, 3-DPG may decrease significantly during hypoxemia. It also decreases in the blood cell products during storage.

Red cell 2, 3-DPG in stored blood diminishes in storage and is effectively zero after 1-2 weeks (rate of decline depends on types of preservative used). After transfusion, red cell 2, 3-DPG returns to 50% after 7 hours and to normal level after 48 hours.

Answer 671

A

Dosage Adjustments of Insulin Peri-operatively

Pre-operatively, patients on rapid or short-acting insulin can continue it till the day of surgery without any other changes.

Those taking intermediate* insulin (usually twice a day dose) *should take only 75% of the normal dose the night before surgery* and *50% of the normal dose the day of the surgery.

With long-acting insulin, the patient needs to reduce their dose by 50% on the morning of the surgery.

Answer 672

A

This has led to the recommendation that metformin be continued until the day of the surgery.

The exception is patients with renal dysfunction, who will need to discontinue the metformin 24-48 hours prior to surgery.

Answer 673

A

The greater the solubility (Ex: Isoflurane is most soluble) of an inhaled anesthetic, the more rapid the uptake into the bloodstream
- The greater the uptake, the slower the rate of rise of FA/FI

(Ex: Hence why Iso is so slow)

Answer 674

A

Cardiac output (Low Cardiac output will increase rate of rise but only with Iso)
Solubility (Iso vs. Des)
Alveolar-to-venous partial pressure difference

(#3 Ex: Low (PArterial - PVenous), meaning less blood uptake
A high pulmonary artery to pulmonary vein gradient means high solubility in the blood. A higher blood solubility means lower diffusion into the CNS, which slows onset.)

Answer 675

A

Non-hemolytic febrile transfusion reaction

Non-hemolytic reaction is defined as a temperature increase of >1 °C without concurrent hemolysis.

A non-hemolytic febrile transfusion reaction occurs because recipient antibodies cause lysis of donor leukocytes found in the red cell transfusion product.

Answer 676

A

Antibodies in the donor blood bind to the recipient’s leukocytes, which then adhere to the vascular capillary bed in the pulmonary circulation.

This causes damage and extravasation of intravascular fluid.

Answer 677

A

Transfusion of soluble leukocyte mediators

Answer 678

A

GP IIb-IIIa receptor inhibitors that prevent platelet aggregation and thrombus formation.

Answer 679

A

adenosine diphosphate (ADP) receptor inhibitors which impair the ADP-dependent activation of the GP IIb-IIIa complex.

Answer 680

A

GP IIb-IIIa receptor inhibitors and thus prevent platelet aggregation and thrombus formation.

Answer 681

A

K = Always efflux

Ca = Influx

Answer 682

A

Excessive bicarbonate administration

Conversion (such as citrate or lactate to HCO3 by the liver)

Excessive chloride loss such as with nasogastric suctioning

Increased renal reabsorption (hyperaldosteronism)

Volume contraction (as seen with diuretic therapy).

Answer 683

A

CV: Cardiac depression, Arrhythmia and vasoconstriction

Pulm: Impaired central respiratory drive and Difficult ventilator weaning

Hypokalemia

Answer 684

A

Treatment involves correction of the cause

(e.g. volume resuscitation with normal saline increases chloride, which increases renal bicarbonate losses)

Acetazolamide (promotes renal bicarbonate loss)

Infusions of acid such as ammonium chloride

Dialysis.

Answer 685

A

A general rule of thumb is that for every 1 mEq/L increase in serum bicarbonate, the PaCO2 should increase by 0.5 mm Hg.

This mechanism is limited by stimulation of peripheral chemoreceptors to hypoxemia and thus PaCO2 rarely increases above 55 mm Hg.

Answer 686

A

The Bainbridge reflex increases heart rate* by inhibiting parasympathetic activity when stretch receptors located in the *right atrial wall sense increased pressure.

Reverse Bainbridge Reflex during after spinal

More common in patients with high baseline vagal tone, anesthetic levels above T5, and is associated with decreased cardiac preload

Answer 687

A

Prevents overinflation of the lungs

When subjected to excessive stretching (e.g. during CPAP or PEEP), pulmonary stretch receptors trigger the reflex which temporarily prevents inspiration and allows expiration to occur.

Answer 688

A

Begins 2-3 weeks following acute injury.

It may occur with stimulation below the level of spinal cord injury leading to uninhibited sympathetic stimulation

Approximately 85% of cases occur with SCI above the T5 level.

Answer 689

A

Usual dose: 20 ppm via mechanical ventilation circuit; dosage range: 5 to 20 ppm

Answer 690

A

Unlike in OSA, there is no effort to breathe during periods of apnea in CSA.

Thus one of the classic signs of OSA, snoring, does not commonly occur in patients with pure CSA.

Most cases of CSA are secondary to an underlying medical condition (e.g., heart failure, stroke, certain neuromuscular disorders), narcotic use, or altitude changes.

Answer 691

A

≥5 episodes per hour of sleep of complete cessation of airflow during breathing lasting ≥10 seconds despite maintenance of neuromuscular ventilatory effort, accompanied by an SaO2 decrease of at ≥4%

Answer 692

A

The total number of episodes of apnea or hypopnea* (reduction of airflow of greater than 50%) divided by the *total sleep time creates a apnea/hypopnea index (AHI).

An AHI of 5-15 events per hour indicates mild disease

An AHI of 15-30 indicates moderate disease

Severe disease is indicated by an AHI of >30.

Answer 693

A

1) Primary hemostasis: platelets form a clot to plug vascular injury.
2) Coagulation: fibrin forms mesh over the clot to stabilize it.
3) Fibrinolysis: after the injury is repaired, the clot is broken down.

Answer 694

A

Liver disease affects all 3 phases (Hemostasis, Coagulation, Fibrinolysis).

Patients with advanced liver disease have dysfunction of BOTH procoagulants and anticoagulants. This creates a balance in the coagulation system and these patients rarely have spontaneous bleeding or clotting.

Answer 695

A

1. Platelet count

2. Platelet function analysis

3. Von Willebrand Factor (vWF)

4. Bleeding time

Answer 696

A

Appropriate platelet count is necessary to generate adequate thrombin levels. This threshold is thought to be around 50-60.

Answer 697

A

Factor VIII and vWF, are produced in the endothelial cells and are not reduced in liver disease. In fact, they are increased.

Answer 698

A

They are NOT at increased risk for spontaneous bleeding. This is because in liver disease the procoagulants and anticoagulants are both decreased. As long as there is adequate platelet count, patients with liver disease will continue to generate thrombin and fibrin. However, as the liver disease advances, it becomes more difficult to maintain hemostasis even with the balance that has been established. Some shift towards clotting, and others towards bleeding.

Answer 699

A

Coagulation management in liver disease patients:

1) Maintain platelet count at 50-60; in high-risk surgery maintain >100
2) Keep fibrinogen >100
3) Transfuse to maintain Hgb > 7
4) Do not give FFP prophylactically or chase INR levels
- Increased INR in these patients does not necessarily reflect risk of bleeding
- If FFP is to be given, dose is 20-40 mL/kg

Answer 700

A

One lead = V5 (75%)

Two Leads = II and V4 (82%)

Intraoperative monitoring of Leads II and V4 is the preferred lead combination as it allows for rhythm monitoring and is sensitive for myocardial ischemia. Alone, V5 has the highest sensitivity for myocardial ischemia, however, this is not recommended for intraoperative monitoring.

Answer 701

A

Meperidine’s beneficial effects are multimodal and center around the kappa opioid receptor.

Answer 702

A

Pressure measurement via simple manometry, also referred to as tube or column manometry, is performed by attaching tubing to the thin-walled needle or the catheter that has been inserted into the presumed central venous site prior to dilation.

This tubing is then held below the level of the vein, allowing blood to fill the tubing followed by raising it vertically above the patient against gravity.

The blood-air interface will settle at the level where hydrostatic pressure in the tubing is equal to the intravascular pressure. If it is misplaced in the artery, the blood will rise out the top of the tubing.Recall that a pressure of 10 mmHg correlates with a height of 15cm.

Answer 703

A

Indications:

Seizure Prophylaxis for preeclampsia
Tocolytic agent in preterm labor
- relaxing uterine smooth muscle and vascular tone

1.8 - 2.5 mg/dL Normal

Answer 704

A

4.8 - 9.6 mg/dL Therapeutic for obstetric floor

Flushing, nausea, vomiting, sedation, dizziness, and muscle weakness

Muscle weakness results from both a decreased release of acetylcholine (secondary to presynaptic calcium channel blockade) as well as decreased motor end plate sensitivity to acetylcholine.

Answer 705

A

Patient has hypermagnesemia therefore hypocalcemia

If these patients need general anesthesia, one must be aware that they may not have fasciculations with succinylcholine, and they will have an increased sensitivity to nondepolarizing neuromuscular blockers necessitating a decreased dose

Answer 706

A

6 - 12 mg/dL ECG changes begin

Prolonged PR interval, widened QRS, Look for heart blocks

Answer 707

A

12 mg/dL Loss of Deep Tendon Reflexes, Respiratory Depression

18 mg/dL The SA and AV node blocked → complete heart block

20-25 mg/dL Cardiac arrest (asystole)

Answer 708

A

Correction of excessive microvascular bleeding in the presence of a INR > 2

2._ Correction of excessive _microvascular bleeding secondary to coagulation factor deficiency* in patients transfused with more than one blood volume
3. Urgent reversal of warfarin therapy
4. Correction of known coagulation factor deficiencies for which specific concentrates are not available
5. For heparin resistance

Answer 709

A

5 - 8 mL/kg then recheck values to guide resuscitation

Answer 710

A

PO = Most pre-dictable

IV = Can have anaphylaxis

SQ/IM not recommended

24 hours to take effect regardless of route

Answer 711

A

It should be noted that some products available in the U.S. contain negligible amounts of factor VII which is key for clotting in trauma patients (these products are known as three-factor PCCs).

Four-factor PCC contains higher amounts of factor VII.

Answer 712

A

Warfarin Reversal, Urgent Surgery:
INR 1.5 - 1.9: consider PCC, FFP may not be useful

Answer 713

A

INR 1.9 - 5:

PCC or FFP

1-3 mg of IV vitamin K

Kcentra, Beriplex P/N [Canadian product]: Vitamin K antagonist (VKA) reversal in patients with acute major bleeding or need for an urgent surgery/invasive procedure:

IV: Individualize dosing based on current pre-dose INR. Dosage is expressed in units of factor IX activity. Administer with vitamin K concurrently. Repeat dosing is not recommended (has not been studied).

Pretreatment INR: 2 to <4: Administer 25 units/kg; maximum dose: 2,500 units

Pretreatment INR: 4 to 6: Administer 35 units/kg; maximum dose: 3,500 units

Pretreatment INR: >6: Administer 50 units/kg; maximum dose: 5,000 units

Answer 714

A

*PCC**: 50 U/kg (Max dose of 5000 units)
*FFP** (5-8 cc/kg)

Vitamin K 2-5 mg IV over 30 minutes

Answer 715

A

Kcentra, Beriplex P/N [Canadian product]:

Administer at room temperature at a rate of 0.12 mL/kg/minute (~3 units/kg/minute); do not exceed 8.4 mL/minute (~210 units/minute).

Do not allow blood to enter into syringe (fibrin clot formation may occur).

Answer 716

A

For INR 1.5 - 1.9

1 mg PO Vitamin K

Answer 717

A

INR 1.9 - 5:

1 - 2.5 mg PO vitamin K*, if INR still elevated 24 hours after dose give *1 - 2 mg PO vitamin K

Answer 718

A

INR 5 - 9

2.5 - 5 mg PO vitamin K, if INR still elevated 24 hours after dose give 1 - 2 mg PO vitamin K

Answer 719

A

Do not administer twice daily prophylactic doses of LMWH while a neuraxial catheter is in place.

You may administer once daily prophylactic doses of LMWH while a neuraxial catheter is in place starting 12 hours after needle insertion.

Answer 720

A

For patients that were receiving therapeutic doses (1 mg/kg) of LMWH, wait 24 hours after the last dose.

For patients that were receiving prophylactic doses (30-40 mg BID) of LMWH, wait 12 hours after the last dose.

Answer 721

A

Do not administer therapeutic doses of LMWH while a neuraxial catheter is in place.

Do not administer twice daily prophylactic doses of LMWH while a neuraxial catheter is in place.

You may administer once daily prophylactic doses of LMWH while a neuraxial catheter is in place starting 12 hours after needle insertion.

Answer 722

A

12 hours after last LMWH dose

Answer 723

A

4 hours

Answer 724

A

Age

Site of Injection

Position

Airway Pressure

Local Anesthetic Concentration

Local Anesthetic Volume

Answer 725

A

- Older = Greater spread

Decreased compliance of epidural space

Therefore space will expand less when LA injected thus cranial & caudal spread increases

Less fat in epidural space in older patients so spread is more

Answer 726

A

Thoracic spread caudally

Low Thoracic spread cephalad

Mid thoracic spread both directions

Answer 727

A

Lateral = More spread (Vs. Sitting)

Trendelenburg results in greater spread of local anesthetics

Answer 728

A

Airway Pressure

Mechanical ventilation with CPAP increases spread

Secondary to compression of epidural space from increased intrathoracic pressure

Answer 729

A

Local Anesthetic Concentration

Increase block height with higher doses

Also affects block density/intensity

Local Anesthetic Volume

Most significant effect on epidural spread and the number of segments blocked

Answer 730

A

Metabolism: Liver

Elimination: GI Tract - Bile and Feces

Answer 731

A

E cylinder Roughly 2000 psi for 660 L

Direct Relationship

I.E. 500 psi = (25% of 660L) = 165 Liters

Answer 732

A

1. Anticholinergic medications

Help restore balance to the dopaminergic and cholinergic balance

Preferred

Diphenhydramine (Both anticholinergic and antihistamine)

Benadryl 12.5 - 50 mg IV

Benztropine

Initial dose: IM, IV, Oral: 1 to 2 mg once.

Subsequent doses: Oral: 1 to 2 mg 1 to 2 times daily.

3-8 all per True Learn but couldn’t find doses

Anticholinergic medications such as diphenhydramine (recall that it is both anticholinergic and antihistamine) and benztropine are considered first-line therapies for EPS since they can rapidly (five minutes or less when administered IV) improve and/or eliminate symptoms. They work by restoring the dopaminergic-cholinergic balance.

Trihexyphenidyl
Atropine
Anti-histamines
Benzodiazepines (Refractory to anticholinergics or when anticholinergics are contraindicated)

Directly relieve muscle spasms

Beta-Blockers (Refractory to anticholinergics or when anticholinergics are contraindicated)
Dopamine Receptor Agonist
Alpha Adrenergic Agonists

Answer 733

A

Multiple Surgeries

Healthcare workers

Atopic Histories

Tropic Fruits - Avocado, Kiwi, Banana, Chestnuts, Stone Fruits

Answer 734

A

Grade I involves cutaneous-mucous signs

Grade II corresponds to mild cutaneous-mucous features that may be associated with cardiovascular and/or respiratory signs

Grade I and II non-life threatening

Cardinal sign of grade III is cardiovascular collapse that may be associated with cutaneous-mucous signs and/or bronchospasm

Grade IV is cardiac arrest

Answer 735

A

Elevated in Anaphylaxis

Peak between 15-60 minutes in Grade I and II

Peak between 30 - 120 minutes in Grade III/IV reactions

Half Life of tryptase = 2 hours

Answer 736

A

SSRIs inhibit CYP2D6 which reduces the activation of many opioids (e.g. codeine, hydrocodone oxycodone) to more potent forms (e.g. morphine, hydromorphone, oxymorphone).

Answer 737

A

Codeine → Morphine

Hydrocodone → Hydromorphone

Oxycodone → Oxymorphone

Answer 738

A

Hydrocodone → Hydromorphone

Slightly weaker analgesic than morphine

Conversion increases analgesic potency by a factor of 4

Oxycodone → Oxymorphone

Slightly stronger than morphine

Conversion increases its analgesic potency by a factor of 2

Answer 739

A

Decrease number and causes aggregation

Answer 740

A

Blocks the musculocutaneous, radial, ulnar, and median nerves

Fails to block the medial aspect of the upper arm supplied by the intercostobrachial nerve* (not a branch of the brachial plexus) and therefore supplementation of the supraclavicular block with an *intercostobrachial nerve block may be needed to prevent tourniquet pain.

Answer 741

A

Block the lateral & Medial antebrachial cutaneous nerve

Answer 742

A

Methoxyflurane created the largest concentrations of inorganic fluoride ions and fluoride-induced nephrotoxicity. Enflurane was related to renal concentration effects of fluoride ions causing nephrotoxicity. Sevoflurane produces more fluoride ions than enflurane while being administered, but the concentration of fluoride rapidly declines with cessation of administration, owing to its low blood and tissue solubility.

Fluoride ion production: methoxyflurane > sevoflurane > enflurane > isoflurane > desflurane.

Answer 743

A

Dosing: SubQ: 0.25 mg/dose;

may repeat every 20 minutes for 3 doses (maximum: 0.75 mg/1-hour period) (NAEPP 2007)

Answer 744

A

3U load and begin infusion at 18U/hour

Repeat 3U loads every 3 minutes and increase gtt to 46U/hour

Answer 745

A

0.2 mg IM

q20 min x2 then q2-4 hours

Answer 746

A

0.25 mg IM

q20 min don’t exceed 8 doses in 24 hours

Answer 747

A

HTN

Headache

N/V

Pulmonary Hypertension

Chest Tightness

Answer 748

A

N/V

Flushing

Bronchospasm

Diarrhea

Pulmonary Hypertension

Answer 749

A

600 - 1000 mcg buccal mucosa/OR

10 minute onset

SE: 38.1 Temp anad N/V, diarrheaa

Answer 750

A

Clinically indistinguishable from anaphylaxis

Mechanism: Uncontrolled histamine release by a mechanism not involving IgE.

Triggers: Protamine, IV contrast dye, opioids, d-tubocurarine, and thiopental.

Tryptase will rise

Answer 751

A

Volatile anesthetics potentiate (Increase) neuromuscular blockade by DECREASING sensitivity of the postjunctional membrane to depolarization* and *INCREASING skeletal muscle blood flow which both augment neuromuscular blockade.

In addition, potentiation of neuromuscular blockade occurs by depression of upper motor neurons.

Answer 752

A

Renal Allografts enhanced survival - The only established clinical effect of TRIM

Answer 753

A

PAO2 = [(Patm – PH2O) * FiO2] – (PACO2 / R)

Where:
PAO2 = alveolar oxygen tension

Patm = barometric pressure

PH2O = water vapor pressure

FiO2 = percent of inspired oxygen

PACO2 = alveolar carbon dioxide tension

R = respiratory quotient (CO2 produced per O2 consumed).

Answer 754

A

A normal A-a gradient is < 10 mm Hg

normal a-A ratio is >0.75.

Answer 755

A

Pressure on Carotid Sinus

Sensory fibers increased that send action potentials to the cardioregulatory and vasomotor centers in the medulla oblongata

(See image below)

Answer 756

A

In doses of 25-50 mcg/kg (max dose of 4 mg) significant amnesia may remain up to 4-6 hours after a dose without excessive sedation, but above 4 mg there is no added benefit and it will prolong sedation.

IV: 1 to 4 mg or 20-40 mcg/kg (maximum single dose: 4 mg) once 5 to 20 minutes before procedure; if needed based on incomplete response and/or duration of procedure, may repeat the dose (usually at 50% of the initial dose) after ≥5 minutes

Answer 757

A

Midazolam = 2 hours

Lorazepam = 6-8 hours

Answer 758

A

Management of pipeline failure or gas crossover:

1) Disconnect the pipeline connection at the wall.
2) Open the emergency oxygen cylinder fully.
3) Ventilate by hand with the anesthesia breathing circuit.

Answer 759

A

Hypercalcemia –> Antagonizes non-depolarizing neuromuscular blockade therefore you need higher doses

Magnesium = Opposite

Answer 760

A

Less respiratory depression (<10%) compared to prop (10-25%)

Onset is slower (4-10 minutes)

Answer 761

A

1. Paresthesias >50% of patients (an abnormal sensation, typically tingling or pricking)

5 minutes after pushing

burning, tingling, and/or stinging sensations and usually occur in the perianal or genital regions

Can be buttock, chest, ears, nose

Resolve spontaneously

LA, NSAIDs, or opiates don’t decrease incidence

2. Pruritits 15-30% of patients (Genitals)

Answer 762

A

Acidiotic –> more H+ attach to albumin –> Hypercalcemia

Alkalosis –> Less H+ attach to albumin –> Hypocalcemia

Answer 763

A

The signs of citrate toxicity include those associated with hypocalcemia

Hypotension

Arrhythmias

narrow pulse pressure

Increased intraventricular end diastolic pressure

Increased central venous pressure

Answer 764

A

The following diagnoses should be considered in patients with a large R wave in lead V1:

1) Right ventricular hypertrophy (RVH)
2) Posterior wall MI
3) Wolff-Parkinson-White syndrome (WPW)
4) Muscular dystrophy
5) Right atrial enlargement (RAE)
6) Right ventricular strain with ST-T wave abnormalities

Answer 765

A

Hypernatremia = Increase MAC

Hyponatremia = Decrease MAC

Answer 766

A

Hypocarbia = Increase MAC

Hypercarbia = Decrease MAC

Answer 767

A

Coronary venous drainage ultimately converges in the coronary sinus, which subsequently empties into the posterior right atrium.

While 85% of coronary blood flow to the left ventricle empties into the coronary sinus

15% will eventually drain via Thebesian veins into the atrial and ventricular cavities.

Answer 768

A

Anterior = RCA

Great = LAD

Middle = PDA

Answer 769

A

Internal Branch of Superior Laryngeal Nerve (CN X) = Sensory above the cords

Recurrent Laryngeal Nerve (CN X) = Sensory below cords and Trachea

Answer 770

A

Greatest to Least:

Desflurane (60% increase)

Isoflurane and Sevoflurane (40%)

Nitrous Oxide (20%)

Answer 771

A

Thromboxane

Responsible for platelet aggregation (Aspirin blocks this)

The prevention of its formation by aspirin prevents platelet aggregation for the life of the platelet.

Thromboxane is also a potent vasoconstrictor, and its inhibition may promote coronary perfusion.

Answer 772

A

*Characteristics of addicted anesthesiologists include:**
50 percent < 35 years old (bimodal distribution) Young
Residents are over-represented. “Often they are the last individuals in your department you would expect.”

A high proportion are members of Alpha Omega Alpha.

67-88 percent are male
75-96 percent are White
76-90 percent opioids were the drug of choice
33-50 percent of polydrug users
33 percent with a family history of an addictive disease
65 percent were associated with academic departments (greater vigilance and younger age)

Answer 773

A

Lithium prolongs action of both depolarizing and nondepolarizing neuromuscular blockers.

Answer 774

A

Mivacurium

Answer 775

A

Decreasing barometric pressure (higher output) will increase the output of the vaporizer.

Answer 776

A

Urine Osmolality
Urine Sodium
FENa or FEUrea (if on diuretics)
BUN/Creatinine

Answer 777

A

Prerenal: UOsm of >500, UNa of <10, FENa of <1%, BUN/Cr of >20

Intrinsic: UOsm of <350, UNa of >20, FENa >2%, BUN/Cr of <15

Post renal: UOsm of <350, UNa of >40, FENa of >4%, BUN/Cr of >15

Answer 778

A

The gold standard for the distinction between the two is the kidneys response to a fluid challenge.

If enough fluid is given to reverse signs of volume depletion and the serum creatinine does not return to baseline within 72 hours, ATN is the likely diagnosis.

Answer 779

A

The presence of “muddy brown casts” of epithelial cells found in the urine during urinalysis is pathognomonic for ATN

Answer 780

A

Mechanism: Vasopressin receptor type 2 (V2) antagonist.

Indications:

Tolvaptan was originally approved for use in patients with acute heart failure

Now used in patients with excessive antidiuretic hormone secretion (SIADH).

Answer 781

A

The average FRC in the adult is approximately 30 ml/kg

(~2100 mL for a 70 kg adult).

Answer 782

A

The greatest decrease in functional residual capacity (FRC) occurs when going from 60° upright to supine (0°) or when being placed in Trendelenburg (head-down) more than -30°.

The FRC does not significantly decrease when changing from a supine position to Trendelenburg less than -30°.

However, beyond -30°, the drop in FRC is considerable

Answer 783

A

Less susceptible to SCh (Give a higher dose)

more susceptible to non-depolarizing NMBDs (Give a lower dose)

Answer 784

A

1) Esophageal
2) Tympanic
3) Pulmonary artery
4) Nasopharyngeal

Answer 785

A

Consequences of Hypothermia

Coagulopathy

Increased infections

Changes in oxygen delivery

Increase in myocardial oxygen demand

Increase in blood transfusion requirements

Poor wound healing

Changes in drug metabolism

Answer 786

A

Decrease in pH (Right shift)

Decrease in 2,3 DPG (Left shift)

Increase in Potassium

Potassium gradually moves out of PRBCs during storage in order to maintain electrochemical neutrality with the hydrogen ions that are generated from anaerobic metabolism. After three weeks of storage, potassium levels may reach 20-35 mEq/L*, though there is usually only 20-60 mL of plasma in one unit of PRBCs. After 4-5 weeks of storage, transfusion of one unit of PRBCs can add *5-7 mEq of potassium. Massive transfusions, particularly in neonates, can lead to hyperkalemia.

Answer 787

A

After the first 24 hours following the burn injury and has implications for both depolarizing and nondepolarizing neuromuscular blocking drug use. When the burned area exceeds 10% of the total body surface area (TBSA), succinylcholine administration between 24 hours and 1 year after the injury becomes contraindicated due to exaggerated hyperkalemia.

Answer 788

A

Starting 1 week following the burn and peaking approximately 5-6 weeks following the injury.

The resistance is primarily due to the significant increase in the number of acetylcholine receptors but is also due to production of altered isoforms of the acetylcholine receptor, increased renal excretion, and altered serum protein binding of the drugs.

Resistance leads to an increased time to onset (slowed up to 30%), decreased duration of action, and decreased overall effect. These effects can be at least partially overcome by increasing the dosage of the drug

Answer 789

A

Vasodilators

Answer 790

A

Ionotropes and Vasodilators

Answer 791

A

Increase in preload (IVF bolus)

Answer 792

A

Incompetent Expiratory Valve

1. Replace Exhausted CO2 absorbent

2. Increase gas flows

Answer 793

A

Incompetent Inspiratory Valve

Answer 794

A

Butorphanol

Mechanism:

Partial Opioid Agonist and Mixed Agonist-Antagonist

Synthetic mu agonist-antagonist opioid analgesic

Partial agonist activity at the κ-opioid receptor

Indications:

Relieve Biliary Colic

Side Effect: Does not cause biliary spasm, does not sufficiently contract sphincter of Oddi and increase common bile

Answer 795

A

The recommended precurarization dosage for a nondepolarizing agent is 10% of the ED95, given about 3-5 minutes prior to succinylcholine. Using 10% of the intubating dose (20% of the ED95) is associated with an unacceptably high rate of side effects, including dyspnea in an awake patient.

Rocuronium

ED 95 - 0.3 mg/kg

Precurarization - 0.03 mg/kg

Answer 796

A

1. Decreases in SSEP amplitude

2. Increases in latency are indicative of insults to the somatosensory pathway such as cerebral ischemia.

Answer 797

A

Thromboelastography (TEG) is both a quantitative and graphic evaluation of clotting function. Decreased MA values primarily suggest quantitative and/or qualitative platelet dysfunction or, to a lesser extent, inadequate fibrinogen.

The best treatment is administration of platelets.

Answer 798

A

Midazolam and all benzodiazepines cause a dose dependent decrease in minute ventilation.

The decreased minute ventilation is mainly a result of decreased tidal volume.

Benzodiazepines decrease the respiratory sensitivity to CO2 and act synergistically with opioids.

Answer 799

A

Decrease in tidal volume, which causes a decrease in minute ventilation.

The respiratory rate is often preserved, but with higher doses of medication apnea may occur.

The depression in minute ventilation seen after midazolam occurs rapidly (less than 5 minutes) and lasts for about 1 hour.

Synergistic with opioids to depress minute ventilation.

Answer 800

A

Lorazepam

Answer 801

A

Note, these maximum allowable doses are based on the duration of action and half-life of each local anesthetic (LA). The maximum allowable doses are for the following time windows:

Chloroprocaine: 30-60 minutes for 12 mg/kg

Lidocaine: 60-90 minutes for:

Lidocaine without Epi - 5 mg/kg

Lidocaine with Epi - 7 mg/kg

*Ropivacaine**: 90-120 minutes for 3 mg/kg
*Bupivacaine**: >120 minutes at 2.5 mg/kg

Answer 802

A

More likely in females of child bearing age having minor surgery

Answer 803

A

Pretreatment with a nondepolarizing muscle relaxant

2. Administration of lidocaine

3. NSAIDs have all been tested and found to decrease the incidence of myalgias from succinylcholine.

Answer 804

A

Lingual nerve, recurrent laryngeal nerve, and hypoglossal nerve.

Risk factors include:

Overinflation of a small-fitting cuff

Prolonged operative times (>2-4 hours)

Lidocaine lubrication

Difficult insertion

Use of nitrous oxide

Cervical joint disease

Answer 805

A

Hofmann elimination reaction is a pH- and temperature-dependent reaction

Proceeds more readily when pH (alkalotic) and temperature are increased

Answer 806

A

An intubating dose of cisatracurium (0.1-0.15 mg/kg)

Duration of action: 30-60 minutes

Elimination half-life: 22-25 minutes

Answer 807

A

Relative contraindications to the use of closed circuit or low flow anesthetic techniques include:

sevoflurane use and patients with alcoholism, malnutrition, cirrhosis, or ketoacidosis.

Answer 808

A

The required FGF (oxygen) can be determined by calculating the metabolic demand for oxygen, approximately 3-3.5 mL/kg/min (for adults) * patient weight in kilograms.

Ex: 100 kg guy should get 350 mL/min of oxygen flow

Answer 809

A

Stent type: Minimum duration of DAPT:

Bare-metal stent 30 days

Drug-eluting stent 3 month minimum, 6 month ideally

Answer 810

A

Advancing age
Lower educational level
History of previous CVA w/o impairments

Answer 811

A

Small doses of succinylcholine (e.g. 0.1-0.5 mg/kg) can be used.

Answer 812

A

The Larson maneuver involves medial and cephalad pressure at the laryngospasm notch.

The notch is located just behind the earlobe, bordered by the base of the skull superiorly, the mastoid process posteriorly, and the ramus of the mandible anteriorly.

Answer 813

A

The diagnosis of carbon monoxide poisoning is made by co-oximetry, when elevated levels of COHb (>15%) are found on arterial or venous blood gas analysis.

Answer 814

A

A bolus of 1.5 mL/kg (20%) should be delivered over one minute followed by an infusion of 0.25 mL/kg/min.

The infusion should be run until at least 10 minutes following restoration of cardiovascular stability.

The infusion may be increased to 0.5 mL/kg/min in the setting of persistent hypotension

Bolus (1.5 mL/kg) may be repeated 2x in the setting of continued cardiovascular collapse

Answer 815

A

Epinephrine by itself is highly arrhythmogenic and these effects may be even more pronounced in the setting of LAST.

Animal studies do not support its use

Animal studies have shown that lipid-only resuscitation of bupivacaine toxicity had better outcomes than epinephrine-only resuscitation due to the presence of severe arrhythmias seen in the latter.

Despite this, the use of small doses of epinephrine is still recommended since epinephrine provides critical inotropic and vasopressor support.

Answer 816

A

Afferent Branch - Internal Branch of superior laryngeal nerve

The internal branch of the superior laryngeal nerve is responsible for sensory innervation of the trachea at and above the level of the vocal cords. This means that the internal branch of the superior laryngeal nerve functions as the afferent limb of the laryngospasm reflex.

Efferent Branch - Recurrent Laryngeal nerve

The efferent branch of the laryngospasm reflex is mediated by the recurrent laryngeal nerve. The recurrent laryngeal nerve innervates all the intrinsic muscles of the larynx, with the exception of the cricothyroid muscle. The lateral cricoarytenoid and transverse arytenoid muscles are major adductors of the vocal cords and responsible for laryngospasm

Answer 817

A

The central venous pressure (CVP) tracing includes 3 waves (a, c, v) and 2 descents (x, y).

The a-wave is caused by right atrial contraction.

The c-wave occurs when the right ventricle contracts, causing the tricuspid valve to bulge into the right atrium.

The emptying of the right ventricle produces the x-descent.

The v-wave is due to the filling of the right atrium

y-descent is the passive emptying of the right atrium.

Answer 818

A

Nicotinic

Skeletal muscle* and *autonomic ganglia

Muscarinic

End organ receptors on salivary/gastric glands

Smooth muscle [bronchial, gastrointestinal, bladder, and vascular]

SA and AV nodes of the heart

Answer 819

A

Bradycardia and Hypotension

Answer 820

A

Bronchospasm

Increased respiratory secretions

Answer 821

A

Increased peristalsis, salivation, GI secretions

Answer 822

A

Miosis

Decreased intraocular pressure

Answer 823

A

Excessive neostigmine may lead to a depolarizing block, similar to succinylcholine, because of excessive motor end plate depolarization by acetylcholine.
In addition, some animal studies have shown that neostigmine might directly block the acetylcholine receptors in high doses.
Lastly, neostigmine can potentiate the effect of succinylcholine by inhibiting pseudocholinesterase

Answer 824

A

Onset = 6-8 hours

Peaks = 30 hours

24 hours to get to 50% (not easily titratable)

Answer 825

A

Mortality rate for physicians re-entering practice after being treated for substance abuse is between 9-13%. For those re-entering training, mortality is 7%.

Answer 826

A

Median

Answer 827

A

Nominal data sets refer to categorically discrete data sets, such as the name of the anesthesia delivered to a patient (e.g. general, regional, local).

Remember, NOMINAL = NAME. The mode, which is a measure of the most frequent value in the data set, is the only measure of central tendency for nominal data sets.

Answer 828

A

One-way analysis of variance (ANOVA)

Answer 829

A

The Poiseuille Law is determined by the equation

Q = (P*pi*r4)/(8*n*l)

where Q = flow rate, P = pressure, r = radius, n = viscosity and l = length of tubing

Answer 830

A

The density of the fluid is not part of the equation and does not directly affect laminar flow rate.

Density is not directly related to Poiseuille’s Law, however, it does help predict if fluid will flow in a laminar or turbulent manner. Poiseuille’s Law only relates to fluid flow that is laminar.

Answer 831

A

In newborns, the dural sac typically ends at S3 and the conus medullaris at L3.

In adults, the dural sac typically ends at S1-S2 and the conus medullaris at L1-L2.

Answer 832

A

Typically, fluid with a Reynolds number greater than 4000 will be turbulent, less than 2300 is laminar, and between is a transition where either can occur depending on other factors such as the roughness of the tubing or plaque in blood vessels.

Answer 833

A

Chi-square testing

Answer 834

A

Platelet Function

Answer 835

A

Glycopyrrolate delays gastric emptying, decreases salivary and gastric secretions, increases heart rate, relaxes bronchial smooth muscle, decreases lower esophageal sphincter tone, and causes urinary retention

Answer 836

A

The duration of action of glycopyrrolate is 2-4 hours so if given shortly before anesthetic induction, the risk of aspiration is slightly increased due to the gastrointestinal side effects discussed above.

Answer 837

A

Sevo > Iso > Des

Sevoflurane undergoes the most extensive metabolism of the inhaled anesthetics used in clinical practice today. Despite demonstrated elevations in serum fluoride concentrations in long cases, it has not been shown to cause fluoride-induced nephrotoxicity.

Answer 838

A

An IV bolus dose of 7 mg/kg may last as long as 10-15 minutes.

Answer 839

A

CPP = AoDP - LVEDP

CPP is coronary perfusion pressure, AoDP is aortic diastolic pressure, and LVEDP is left ventricular end diastolic pressure.

Answer 840

A

Mapleson A is the most efficient user of FGF during spontaneous ventilation, but is the least efficient for controlled ventilation.

Answer 841

A

All Dogs Can Bite (spontaneously): A > D > C > B
Dead Bodies Can’t Argue (controlled): D > B > C > A

Spontaneous = A

Controlled = D

Answer 842

A

The Mapleson F system (also known as the Jackson-Rees modification) is relatively efficient at both spontaneous ventilation (FGF of 2-3 times MV*) and *controlled ventilation (FGF approximately 2 times MV)

Answer 843

A

The Mapleson D system with the Bain modification has the fresh gas inflow tubing running coaxially inside the corrugated breathing tubing. This modification makes it very efficient for CONTROLLED ventilation, typically requiring FGF only 1-2 times MV.

Spontaneous ventilation requires FGF of 1.5-3 times MV to prevent rebreathing.

Answer 844

A

Low-risk patients are those who taking < 5 mg/day of prednisone (or equivalent) regardless of the time duration or patients on glucocorticoid therapy for < 3 weeks regardless of dose.

High-risk patients are those taking > 20 mg/day of prednisone (or equivalent) for > 3 weeks or those with cushingoid symptoms.

Intermediate-risk patients are those taking 5-20 mg/day of prednisone (or equivalent) for > 3 weeks; those who have discontinued glucocorticoid use within the past year; or those who use chronic inhaled or topical glucocorticoids.

Answer 845

A

Stimuli at the eye -> ciliary ganglion -> ophthalmic division of trigeminal nerve -> Gasserian ganglion -> trigeminal nucleus -> vagus nerve -> bradycardia.

Answer 846

A

Leukoreduction is a decrease or complete elimination of donor leukocytes in blood components.

This can reduce the risk of febrile transfusion reactions and the risk of viral transmission (e.g. cytomegalovirus).

It does not fully protect against bacterial infection and does not prevent graft-versus-host disease.

Answer 847

A

At 1.0 MAC of isoflurane, cardiovascular effects include increased heart rate (10-15 beats/min), decreased SVR and blood pressure, and minimal changes in CVP.

Respiratory effects include a mild reduction in minute ventilation, a reduced tidal volume, and an increased respiratory rate.

Answer 848

A

Health care workers, atopic individuals, and those with allergies to certain foods (avocados, bananas, chestnuts, kiwi fruit, papayas, potatoes, tomatoes) have an increased incidence of latex allergy.

Answer 849

A

Nalbuphine is a mu antagonist and kappa opioid receptor agonist which exhibits a plateau effect for respiratory depression.

Answer 850

A

20 minutes

The release of A2 is modulated by the renin-angiotensin-aldosterone system (RAAS).

Blockade of the RAAS by angiotensin-converting enzyme inhibitors or angiotensin receptor blockers may cause profound and refractory perioperative hypotension, particularly after induction of general anesthesia.

Answer 851

A

Normal pulmonary wedge pressure is 6-12 mmHg

Answer 852

A

A “full” E size oxygen cylinder is variously quoted in the anesthesia literature as being pressurized to 1900, 2000, or 2200 psig.

Similarly, major anesthesia textbooks differ in regards to how many liters of oxygen are in a “full” E size oxygen cylinder, most often stating it to be 600, 625, or 660.

Answer 853

A

Drug dosage, drug baricity, and patient positioning are the most important factors influencing level of spinal blockade.

Drug volume is an important factor during epidural blockade.

Answer 854

A

At least 40% of anesthesiology residents who were found to have substance use disorder during training relapsed.

Answer 855

A

Sevoflurane > isoflurane > halothane.

Answer 856

A

1 palpated twitch indicates >90% suppression.
2 palpated twitches indicate 80-90% suppression.
3 palpated twitches indicate 70-80% suppression.
4 palpated twitches indicate up to 65-75% suppression.
Palpation of twitches using TOF testing cannot detect the percentage of receptors bound at < 65%.

Answer 857

A

Physostigmine (0.5 - 2.5 mg IV) may be able to reverse the emergence reactions that are seen with ketamine.

Physostigmine is a centrally acting acetylcholinesterase inhibitor that will increase the amount of acetylcholine in the brain.

The theory behind this mechanism of reversal is that ketamine’s emergence reactions resemble the central anticholinergic syndrome thus, giving physostigmine may shorten the response. However, data is conflicting regarding the reliability of physostigmine for reversal of symptoms.

Answer 858

A

Factors that influence incidence of emergence reactions:

Age: Adult patients are more likely to report a high incidence compared to pediatrics.
Gender: Females are more likely than males.
Dosage: Larger doses with rapid administration increase the risk.
Psychological Susceptibility: Certain personalities types are at an increased risk; those who tend to dream at home and those who score high on the Eysenck Personality Questionnaire (extrovert, neurotic) tend to have a higher risk.
Concurrent Medications: Multiple medications increase the incidence although administering a benzodiazepine prior to administration of ketamine helps decrease the risk.

Answer 859

A

1/C(Resp System) = 1/C (Lungs) + 1/C (Chest wall)

Where C is compliance, RS is respiratory system, L is lungs, and CW is chest wall.

Answer 860

A

A simple face mask supplies an FiO2 of approximately 35-50% with oxygen flows of 5-10 L/min.

Nasal cannulas provide an FiO2 of 25-40% with flow rates up to 6 L/min.

Answer 861

A

An IM dose of 2-5 mg will raise blood pressure and lower heart rate typically within 10-15 minutes from injection.

Answer 862

A

Ketorolac = Vasoconstriction of afferent glomerular arterioles.

Prostaglandins dilate afferent arterioles and increase glomerular capillary perfusion pressure. Ketorolac (and other NSAIDs) inhibit this vasodilatory effect and result in afferent arteriolar vasoconstriction.

Answer 863

A

60-65 mmHg of PaO2

Answer 864

A

1) Relatively long incisors
2) Prominent “overbite”
3) Patient cannot bring mandibular incisors anterior to maxillary incisors
4) Less than 3 cm interincisor distance
5) Uvula is not visible when tongue is protruded with patient in sitting position
6) Highly arched or very narrow palate
7) Mandibular space that is stiff, indurated or occupied by a mass
8) Less than three ordinary finger breadth thyromental distance
9) Short neck length
10) Thick neck circumference
11) Decreased extension or flexion of the neck

Answer 865

A

Metoclopramide is a dopamine antagonist that causes increased gastric motility and increased lower esophageal sphincter tone.

Answer 866

A

The Bohr and Haldane effects are complementary principles that help explain the efficient delivery of O2 to the tissue and CO2 to the lungs.

The Bohr effect states that in areas of high CO2, the hemoglobin has less affinity for O2 which is more readily released for consumption by the tissues.

The Haldane effect states that deoxygenated hemoglobin has a higher affinity for CO2. Once the deoxygenated hemoglobin reaches the lungs, the high O2 concentration decreases this affinity and the CO2 is released.

Answer 867

A

AV nodal blockade

Answer 868

A

The equipment ground wire is the most reliable means to prevent microshock.

The ground fault interrupter* can prevent *macroshocks, but does not reliably prevent microshocks

Answer 869

A

There are three main causes of auto-PEEP:

Dynamic hyperinflation with intrinsic expiratory flow limitation: this occurs in COPD patients. COPD results in loss of elements that keep the lungs open during expiration. During exhalation, the closure of the airways results in air trapping. Applying external PEEP can help relieve this type of auto-PEEP.
Dynamic hyperinflation without expiratory flow limitation: even when the airways are widely patent at the end of exhalation, if the volume delivered is too high, the exhalation time too short, or if exhalation is impeded by a blockage external to the patient (such as with blocked ETT or stuck exhalation valve) then air can get trapped. This is typically seen during rapid breathing patterns, use of high tidal volumes, when inspiration is greater than expiration, or when there is added flow resistance due to small endotracheal tubes. Removing the blockage, decreasing volume, or increasing exhalation time will help alleviate the problem.
Exaggerated expiratory activity without dynamic hyperinflation: when strong expiratory muscle activity contributes to alveolar pressure at the end of the expiratory cycle there will be an end-expiratory gradient of alveolar to central airway pressure. This results in auto-PEEP phenomena even with low lung volumes.

Answer 870

A

From greatest to least, the vapor pressures of the volatile anesthetics are: desflurane > isoflurane > sevoflurane.

Answer 871

A

Nausea and vomiting may be associated with neuraxial block in up to 20% of patients and atropine is almost universally effective in treating the nausea associated with high (T5) neuraxial anesthesia.

Explanation: Unopposed parasympathetic (vagal) activity after sympathetic blockade causes increased peristalsis of the gastrointestinal tract, which can lead to nausea and is the primary mechanism behind nausea after spinal blockade. Atropine is an anticholinergic medication, thus is useful for treating nausea after high spinal blockade.

Answer 872

A

Transurethral surgery of the bladder usually can be performed with spinal anesthesia without further consideration. If the tumor is along the lateral aspect of the bladder then the obturator nerve may be stimulated and the jerk reflex initiated even under spinal anesthesia. An obturator nerve block should be performed to help prevent this. Alternatively, general anesthesia with muscle relaxation can also be performed to prevent the reflex. If neuromuscular blocking agents are not used during general anesthesia, the obturator nerve block will still need to be performed.

Answer 873

A

Cryoprecipitate contains vWF, fibrinogen, fibronectin, factor VIII, and factor XIII.

Brainscape's Knowledge GenomeTM

Basic Exam Flashcards

Brainscape's Knowledge Genome^TM