ITE 2020 - 2021 Flashcards
What are 5 nerves that innervate the foot?
1. Posterior Tibial
2. Sural
3. Superficial Peroneal
4. Deep Peroneal (Deep Fibular Nerve)
5. Saphenous Nerve (Branch of Femoral Nerve)
How and where does the Sciatic Branch branch off?
List their major and minor branches
At popliteal fossa divides into common peroneal and tibial nerves
Common Peroneal
- Superficial Peroneal
- Deep Peroneal Nerves (Deep Fibular Nerve)
Tibial Nerves
- Posterior Tibial
- Sural Nerves
Identify the:
Axillary Vessels (Vein and artery)
Muscles (Tricep, Coracobrachialis) Biceps)
Nerves (Median, Musculocutaneous, Radial and Ulnar)
What is the RIFLE Criteria?
What do the define oliguria as (Include 12 and 24 hours)
The RIFLE criteria
(Risk, Injury, and Failure; and Loss; and End-stage kidney disease) add time frames to oliguria defining it as urine output of:
< 0.5 mL/kg for 12 hour or <400 mL pe rday
urine output < 0.3 mL/kg for 24 hours
What is anuria defined as?
Anuria is defined as urine output < 50 mL in 12 hours or urine output < 50-100 mL in 24 hours
List the RIFLE Criteria for:
GFR Criteria & Urinary Output Criteria for Each of the 5 phases
See images
Risk - Creatinine jumps 1.5x or GFR decreases 25%, UOP <0.5 mL/kg/hr for 6 hours
Injury - Creatinine jumps x2 or GFR decreases 50%, UOP <0.5 mL/kg/hr for 12 hours
Injury - Creatinine jumps x3 or Cr >4 (Acute rise in >0.5 or GFR decreases 75%, UOP <0.3 mL/kg/hr for 24 hours or Anuria for 12 hours
Loss - Persistent Failure = Complete loss of renal function >4 weeks
ESRD = Complete Loss of kidney function for >3 months
What is the biggest difference between HFJV and HFOV?
In HFJV exhalation is passive (depends on passive lung and chest-wall recoil) whereas in HFOV gas movement is caused by in-and-out movement of the “loudspeaker” oscillator membrane. Thus in HFOV both inspiration and expiration are actively caused by the oscillator, and passive exhalation is not allowed
What is important to remember about CO2 removal in both high-frequency jet ventilation (HFJV) and high-frequency oscillatory ventilation (HFOV)?
In both HFJV and HFOV, CO2 removal is inversely proportional to frequency (opposite of what we usually do in conventional ventilation modes).
This is because of the higher the frequency the lower the amplitude, which is the key to CO2 removal.
What are the benefits of centrifugal cardiopulmonary bypass pumps vs. roller pumps?
Less blood element destruction
Lower line pressures
Lower risk of air emboli
Elimination of tubing wear
Elimination of Spallation
What is spallation in terms of CPB (Cardiopulmonary Bypass)?
Spallation = The breakup of a bombarded nucleus into several parts
I.e. Creation of plastic microemboli (spallation),
When referencing certrifugal CPB pumps, why do they require flowmeters?
Centrifugal pumps require flowmeters on the arterial portion of the CPB circuit since flow can vary from alterations in pump preload and afterload.
Centrifugal pump blood flow varies depending on pump preload and afterload.
Are roller CPB pumps preload and afterload dependent in terms of pump flow?
Assuming the inflow and outflow are not occluded, roller pump flow is essentially only dependent on the speed of the rollers
What is the effects of electrolytes (K and Ca) on rapid NaHCO3 administration?
Drop in Both K and Ca
How does Acidosis vs. Alkalosis affect K levels?
In the setting of acidosis, excess hydrogen ions enter cells, resulting in the extracellular movement of potassium to maintain electrical balance, thus increasing the measured serum (K+).
Conversely, during alkalosis, extracellular potassium ions move into cells to balance the extracellular movement of hydrogen ions, resulting in decreased plasma (K+). This is the mechanism behind bicarbonate administration in the setting of severe hyperkalemia.
How does pH affect the ionized free calcium levels?
Acidosis = Hypercalcemia
Alkalosis = Hypocalcemia
Explanation:
Sodium bicarbonate can transiently lower blood calcium levels. Calcium binding to albumin is dependent on serum pH. In states of acidosis, the excess hydrogen ions displace calcium bound by albumin and thus ionized levels of calcium increase. This process is reversed in the setting of alkalosis and should be considered before administering sodium bicarbonate to a patient with pre-existing hypocalcemia.
Bicarbonate can cause hypotension and hypertension
List the mechanisms of why this is both possible.
Hypotension:
- Systemic acidosis causes (a) pulmonary vasoconstriction (b) increased levels of ionized calcium available for cardiac myocytes.
Administration of bicarbonate could therefore result in acute vasodilation and ventricular depression, resulting in decreased blood pressure.
Hypertension
Conversely, proponents of bicarbonate administration argue that severe acidosis can cause cardiac depression and reduced response to vasopressors (which have reduced efficacy at low pH), and thus bicarbonate administration would serve to increase blood pressure.* Additionally, a typical bolus of sodium bicarbonate contains 1,000 mEq/L of sodium, compared with 154 mEq/L in a bag of normal saline, and therefore blood pressure can transiently *increase from an acute osmotic load.
You just slammed 2 amps of bicarbonate in the cardiac room and you notice a patient’s pupils now are asymmetric, the patient is posturing and you have cushings triad hemodynamics.
What happened and why?
ICP Causing herniation
Theoretically, the Sodium Bicarbonate increase in CO2 would cause cerebral vasodilation and increased intracranial pressure, although direct clinical evidence for this has not been found.
What is a normal CVP?
2-6 mmHg
What is a normal PCWP?
6-12 mmHg
What is a normal Cardiac Index?
2.5 - 5 L / min/ m2
What is a normal SVR?
800 - 1200 dynes x sec / cm5
What are the 4 classes of distributive shock?
Distributive shock, also referred to as vasodilatory shock, can be divided into four classes
1. Septic shock
2. Anaphylactic shock
3. Neurogenic shock
4. Shock associated with adrenal crisis.
What are the 3 most anesthetically relevant joint manifestations of RA?
Several joint manifestations of RA can lead to anesthetic difficulties or complications.
- Atlantoaxial subluxation may make intubation more difficult and cause spinal cord trauma with neck manipulation
- Temporomandibular joint synovitis can limit mandibular motion
- Cricoarytenoid arthritis can cause hoarseness, pain on swallowing, and possible postextubation laryngeal obstruction
What are the most common extra articular cardiovascular complications of rrheumatoid arthritis patients?
Left sided regurgitant lesions (Mitral > Aortic)
Pericarditis, cardiomyopathy, myocarditis, cardiac amyloidosis, coronary artery arteritis, accelerated coronary atherosclerosis, cardiac valve fibrosis, cardiac conduction system abnormalities, aortitis with dilation of the aortic root and resultant aortic regurgitation, pericardial effusion, and vasculitis which may lead to visceral or myocardial/cerebral ischemia
Among the valvular diseases associated with RA, mitral valve disease including mitral regurgitation is the most common. Aortic valve disease, especially aortic regurgitation, is also often seen.
Stenotic valve lesions are not typically associated with RA.
Fortunately, most valvular heart disease associated with RA is generally mild.
What are the extra articular pulmonary manifestations of Rheumatoid arthritis?
Pleural effusion, pulmonary hypertension and/or pulmonary interstitial fibrosis which can cause decreased lung volumes and vital capacity (causing a ventilation-perfusion mismatch)
What are the neurological extraarticular manifestations of RA?
Neuro: Peripheral neuropathies (nerve compression, carpal tunnel, tarsal tunnel), chronic pain and keratoconjunctivitis sicca (dry inflammation of the conjunctiva and cornea).
What are the hematological extraarticular manifestations of RA?
Chronic Anemia
Thrombocytopenia
Neutropenia (Felty’s Syndrome)
Felty’s syndrome is a rare, potentially serious disorder that is defined by the presence of three conditions: rheumatoid arthritis (RA), an enlarged spleen (splenomegaly) and a decreased white blood cell count (neutropenia), which causes repeated infections.
What are the renal extraarticular manifestations of RA?
Renal: chronic renal failure possible (drugs, amyloidosis, vasculitis)
All diuretics will do what to urine Sodium and urine Potassium? (One exception)
Increase (Potassium sparing)
How does blood pH change with each class of diuretic?
(Carbonic Anhydrase, Loop, K Sparing and Thiazide)
Blood pH Decreased - Acidemia with carbonic anhydrase inhibitors, K+ sparing
Blood pH Increased - Alkalemia with loop diuretics, thiazides
What is the Wind Up phenomenon?
The wind-up phenomenon is caused by repeated stimulation of peripheral C fibers resulting in increased action potentials at the dorsal horn (spinal synapse) causing an amplified response.
What is the difference in allodynia and hyperalgesia?
Allodynia is a painful response to a non-painful stimulus. This subject was given a painful stimulus.
Hyperalgesia is an exaggerated painful response to an ordinarily painful stimulus.
How do you perform a Lateral Femoral Cutaneous Nerve Block?
The anterior superior iliac spine is an important landmark for performing a lateral femoral cutaneous nerve block.
The LFCN is best blocked where it is located between the sartorius (medial landmark) and tensor fascia lata (lateral landmark) muscles
The nerve can reliably be anesthetized by injecting 10 mL of local anesthetic approximately:
- 1-2 cm medial
- 1-2 cm inferior
to the ASIS at a depth of 0.5-1 cm from the skin.
What is the condition called where the lateral femoral cutaneous nerve is entraped?
Damage to the LFCN can lead to pain and paresthesias on the lateral upper thigh, which may extend down towards the lateral knee. This condition is called meralgia paresthetica and is most commonly caused by entrapment and compression of the nerve as it passes between the inguinal ligament and the ilium. It may also be caused by direct nerve damage, trauma, or diabetic neuropathy.
What are the nerve roots of the lateral femoral cutaneous nerve?
L2-L3
How does respiatory alkalosis affect serum [electrolyte]:
Calcium
Potassium
Phosphate
Explain the pathophysiology of each
All low
Hydrogen-potassium transporters pump hydrogen ions out of cells in the setting of alkalosis in order to restore physiologic pH. Simultaneously, potassium is pumped intracellularly to ensure electroneutrality, thus leading to hypokalemia.
Alkalosis can cause Hypophosphatemia. A rising cellular pH stimulates the glycolytic pathway, enhancing sugar-phosphate production. This triggers increased cellular uptake of phosphorus, thus decreasing serum phosphorus concentration.
Hypocalcemia is caused by increased calcium binding to negatively charged plasma proteins as the proteins release hydrogen ions to restore physiologic pH.
What patient types of high-risk cardiac conditions would qualify “Recommendation for IE Prophylaxis according to 2017 AHA/ACC guideline?
- Prosthetic cardiac valves including transcatheter-implanted prosthetic valves
- Patients with implanted prosthetic material such as annuloplasty rings and artificial chordae tendineae
- Patients with a history of infectious endocarditis
- Patients with a history of unrepaired cyanotic congenital heart disease
- Including cyanotic congenital disease patients with a repair, but with a residual shunt or valvular regurgitation near an implanted patch or device
- Patients with a history of cardiac transplantation who have a regurgitant valvular lesion due to a structurally abnormal valve
In addition to being a high risk patient, what procedure would qualify the need for prophylactic antibiotics to prevent infective endocarditis?
First, only patients who are undergoing dental procedures that “involve the manipulation of gingival tissue…periapical region of teeth, perforation of the oral mucosa, urinary mucosa is peiced in the setting of actuve UTI or colonizataion” are to be considered for prophylactic antibiotics
Infectious Endocarditis in cardiac transplant patients should be prophylaxed for how long post op?
Examples: (frequent central venous catheter placement, frequent endomyocardial biopsies to assess for rejection, intense immunosuppressive therapy, and because of the endothelial disruption that comes from the transplantation surgery itself.)
6 months
What is a type and screen?
Antibody screen:
The recipient’s serum is mixed with commercially supplied RBCs (known as screen cells) containing selected antigens commonly implicated in hemolytic transfusion reactions (other than ABO-Rh).
Antigens not represented in screen cells are unlikely to cause clinically significant hemolytic reactions.
It will detect the vast majority of antibodies that can cause a hemolytic reaction.
What is a type and cross?
The recipient’s serum is mixed with donor RBCs.
What is the chance of cross matching detecting a potentially dangerous antibody that was missed by the antibody screen?
What populations are at risk for this?
It is possible for some patients, especially those with a history of multiple transfusions or pregnancies, to carry antibodies that would not be detected during an antibody screen.
However, the chance of cross matching detecting a potentially dangerous antibody that was missed by the antibody screen is less than 1 in 10,000.
What are the preservatives in:
Aminoester local anesthetics
Aminoamide local anesthetics
What is more likely to cause an allergic reaction
Aminoesters, which are degraded into an allergen, para-benzoic acid (PABA) = More likely for allergic reaction
Aminoamides and their metabolites are not associated with allergens and hypersensitivity reactions. It is more likely that the preservatives in the local anesthetic preparation such as methylparaben are responsible for any allergic reactions.
What are the autonomic changes associated with aging?
Include: Beta receptor, Alpha receptor, Autonomic activity
Increase in sympathetic nervous system activity
Decreased parasympathetic nervous system activity.
Decrease in beta receptor responsiveness
Maintained alpha receptor responsiveness
How are Carcinoid tumors diagnosed?
Presence of excessive amounts of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) in urine.
24 hour urinary 5-HIAA (Metabolite of serotonin) of > 30 mg
Normal 5-HIAA is 3-15 mg (For reference)
How are pheochromocytomas diagnosed?
Urinary Vanillylmandelic acid (VMA) is elevated in patients with tumors that secrete catecholamines.
Norepinephrine is metabolised into normetanephrine and VMA.
What are the usual cardiac manifestations of carcinoid syndrome with right sided involvement?
Cardiac manifestations are due to fibrosis of the endocardium, primarily on the right side. Pulmonic stenosis is usually predominant. The tricuspid valve is often fixed open resulting in regurgitation.
What does the 11 Beta-Hydroxylase hormone do?
11β-hydroxylase is responsible for the conversion of 11-deoxycorticosterone to corticosterone (precursor to aldosterone) and the conversion of 11-deoxycortisol to cortisol.
Explain how Adenosine plays a role in arterial vs. portal vein perfusion of the liver
Adenosine is produced in the space of Mall surrounding the local hepatic vasculature and diffuses into the portal vein.
As portal venous blood flow decreases, the decreased flow allows the accumulation of adenosine in the hepatic vasculature.
This increased concentration of adenosine causes vasodilation of the hepatic artery and increased hepatic arterial blood flow.
As portal venous flow increases, the increased flow washes the adenosine out of the hepatic vascular system resulting in vasoconstriction of the hepatic artery.
This is known as the “adenosine wash-out hypothesis.”
What is the maximum effect of HABR (Hepatic Artery Buffer Response)?
Double the hepatic arterial blood flow
Liver Perfusion
What is the % of blood flow from hepatic artery vs. portal system
What is the % of oxygen of hepatic artery vs. portal system
The liver gets 20-25% of the cardiac output via the portal vein and the hepatic artery.
The portal vein is responsible for 75% of the blood flow while the hepatic artery is responsible for 25% of the blood flow.
However, both vascular structures each deliver 50% of the oxygen supply to the liver.
A decelerating flow pattern on inspiration is characteristic of which method of controlled ventilation?
A decelerating flow pattern on inspiration is characteristic of a pressure control breath.
Volume control delivers the breath to the patient as a what type of breath? Waveform
Volume control delivers the breath to the patient as a fixed flow breath (square waveform).
What spirometry pattern in seen with ascites?
FEV1/FVC
FVC
FEF25-75%
Tense abdominal ascites elicits an extrinsic restrictive lung disease pattern, which is indicated on pulmonary function testing by a:
Decreased forced vital capacity (FVC) (50%)
Both intrinsic and extrinsic restrictive forces lead to a decreased FVC due to a decrease in TLC.
Reduced functional residual capacity (FRC)
The FEV1/FVC ratio (90%) and FEF25-75% are generally normal (90%)
The forced expiratory volume in one second (FEV1) is usually decreased as well because of the reduced lung volumes. Since both the FEV1 and the FVC are reduced with restrictive lung pathology, the FEV1/FVC ratio is usually normal. The forced expiratory flow during the middle 50% of the FVC (FEF25-75%) is typically normal in restrictive lung disease unless small airway damage is also present from other etiologies.
Both the FEF25-75% and the FEV1/FVC ratio are measures of ventilatory capacity.
What is Vital Capacity?
List VC in terms of sums of different lung spaces
Vital capacity (VC) is the maximal amount of air that can fill the lungs and participate in gas exchange.
VC = TLC - RV
VC = IRV + ERV + TV
What is the FRC?
The amount of gas that can be forcefully and maximally exhaled from a maximal inhaled volume is the forced vital capacity (FVC).
What are the FVC, FEV1, FEV1/FVC, FEF25-75%, FRC, and TLC for Restrictive Lung Disease
FVC - Very low
FEV1 - Very low
FEV1/FVC - Normal
FEF25-75% - Normal
FRC - Very Low
TLC - Very Low
What are the FVC, FEV1, FEV1/FVC, FEF25-75%, FRC, and TLC for Obstructive Lung Disease?
FVC - Normal or slightly increased
FEV1 - Very low
FEV1/FVC - Very Low
FEF25-75% - Very Low
FRC - Normal or increased
TLC - Normal or increased
Normally, a patient’s FEV1 is approximately what percentage?
Normally, a patient’s FEV1 is approximately 75-80% of their FVC, meaning that they can exhale 75-80% of their vital capacity in one second.
Normal ranges for FEF25-75% are typically what percentage of the predicted value?
Normal ranges for FEF25-75% are typically 80-120% of the predicted value.
What is the FEV1/FVC ratio for Obstructive Disease?
Why is this?
Patients with chronic obstructive pulmonary disease (COPD) have a lower than predicted FEV1/FVC ratio. This is due to airway collapse with forced exhalation, which leads to a decreased FEV1. Therefore, a reduction in the FEV1/FVC ratio occurs as the patient’s FVC is typically unchanged or slightly increased.
Patients with COPD will also have a what FEF 25-75%?
What is this?
Patients with COPD will also have a low FEF25-75% due to small airway collapse during exhalation.
What is Conn Syndrome?
Primary Hyperaldosteronism
Conn Syndrome has serum levels of:
Sodium?
Potassium?
Renin?
BP?
pH?
HIgh Sodium –> Hypertension
Low Potassium
Low Renin
Metabolic Alkalosis (Chronic Loss of Hydrogen ions)
Conn Syndrome:
Preoperative management?
Intraoperative Management?
Preoperative management = Spirinolactose (Takes weeks), Potassium Supplementation, K sparing diuresis
Intraoperative Management- Avoid hyperventilation (Will decease K more), Cortisol eplacement with bilateral adrenalectomies for multiple aldosteronomas
Why would you want a faster HR for mitral regurgitation?
Chronic MR is typically asymptomatic in its earlier stages due to compensatory mechanisms that reduce afterload and increase left ventricular compliance, promoting forward flow. In its more severe stages, reduced ejection fraction, increased LV pressures and regurgitant volume are seen. This can be remedied by increasing heart rate to reduce systolic time, reducing afterload, and maintaining normal sinus rhythm and normovolemia.
A patient has an MI and found to have new MR.
What happened anatomically? What is the result.
Acute mitral regurgitation may also occur from posteromedial papillary muscle rupture after a myocardial infarction. This papillary muscle has a single blood supply, rendering it more susceptible to ischemia and rupture. Lastly, functional mitral regurgitation may occur from overdistended ventricles such as in dilated cardiomyopathy.
The mitral valve papillary muscles in the left ventricle are called the anterolateral and posteromedial muscles.
- Anterolateral muscle blood supply: left anterior descending artery - diagonal branch (LAD) and left circumflex artery - obtuse marginal branch (LCX)
- Posteromedial muscle blood supply: right coronary artery - posterior interventricular artery (RCA)
The posteromedial muscle ruptures more frequently because it only has one source of blood supply, hence RCA occlusion can cause papillary muscle rupture.
What can Midazolam do to parkinson’s patients?
Also, midazolam may precipitate a worsening of dyskinesias in patients with Parkinson disease.
What electrolyte abnormality is concerning for Digoxin toxicity and why?
Hypokalemia
Digoxin toxicity is more likely to occur in the setting of hypokalemia since digoxin competes with potassium for the same binding site on the Na+/K+ ATPase.
With less potassium, more digoxin is able to bind and its effects (and side effects) become more pronounced.
Digoxin toxicity is also more likely to occur in patients concurrently taking amiodarone, quinidine, or verapamil as these drugs cause an increase in serum digoxin concentration.
What are the 4 benefits of Digoxin?
Benefits:
- Positive inotrope improves contractility
- Decreases HR by slowing AV conduction through the node
- Sympatholytic action on baroreceptors
- Decreases renal sodium reabsorption (mild diuresis)
How does Phenytoin affect neuromuscular blockade?
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.
Chronic phenytoin administration reduces the duration of action and increases the ED95 of aminosteroid NDNBDs by as much as 50%.
What are the 4 combination of multiple different mechanisms responsible for this?
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
What is the enzyme and gene, respectively that is involved in Warfarin?
second enzyme called vitamin K reductase (encoded by the VKORC1 gene) is responsible of regenerating active (reduced) vitamin K.
Warfarin is metabolized by what cytochrome P450 isoform?
Warfarin is metabolized by the cytochrome P450 2C9 isoform (CYP2C9)
Warfarin is avoided in pregnancy because of?
Teratogenic
Warfarin must be avoided in pregnant women because it can cause abortion, fetal hemorrhage, and birth defects (nasal hypoplasia, stippled epiphyseal calcifications).
Of all the Vitamin K dependent factors (10, 9, 7, 2, Protein C/S) which affect PT/INR?
PT/INR is the method of choice to monitor warfarin therapy since it is prolonged by reduced functional levels of the vitamin K-dependent factors II, VII, and X. (1972 C/S)
Of note, not all vitamin K-dependent factors affect PT/INR (e.g. factor IX, proteins C, S, and Z do not), while reductions in some vitamin K-independent factors, such as fibrinogen and factor V, can also prolong PT/INR.
Can Warfarin be given during breastfeeding?
Warfarin is not present in milk and can be safely given to nursing mothers.
(Cannot be given during gestation as it is teratogenic)
Draw a Normal Flow Loop
Include:
TLC, VC, RV
Label Axis
Label Expiration and Inspiration
What flow loop is seen here?
A variable INTRAthoracic airway obstruction (e.g., distal tracheal tumor or mediastinal mass) produces a flow-volume loop with a plateaued EXPIRATORY curve and the flow rate is usually decreased.
During expiration, intrathoracic pressure becomes positive which further decreases the airway diameter, enhances the degree of obstruction, and impairs airflow. The inspiratory curve is usually normal since the negative intrathoracic pressure generated during inspiration helps keep the airway open.
What flow loop is seen here?
A variable EXTRAthoracic airway obstruction (e.g., vocal cord paralysis or dysfunction, proximal tracheal tumor, glottic strictures) produces a flow-volume loop with a plateaued INSPIRATORY curve and the flow rate is usually decreased.
During inspiration, the negative inspiratory pressure causes the obstruction to increase. The expiratory curve is usually normal since the positive airway pressure generated during expiration helps keep the airway open.
What flow loops is seen here?
A fixed upper airway obstruction or fixed large airway obstruction (e.g., foreign body, tracheal stenosis, large airway tumor) impairs BOTH inspiration and expiration leading to a flow-volume loop with plateaued and decreased inspiratory and expiratory flows.
How do you tell the difference between a Flow-Volume loop of obstructive vs. restrictrive lung disease?
Restrictive = Moves to the Right
Obstructive = Moves to the Left
What is the characteristic of thyrotoxic cardiomyopathy in terms of histological changes?
Triiodothyronine (T3) exerts direct effects on the myocardium and may result in thyrotoxic cardiomyopathy, characterized by fibrotic and fatty changes with lymphocytic and eosinophilic infiltration.
How does RV, TV, TLC< and VC change with aging?
RV = Increases TV = No change
TLC = Decrease
VC = Decrease
What is the most common indication for retrograde cardioplegia?
Aortic Valve Insufficiency
How does nitric oxide inhaled work?
What is the half life?
How does it affect V/Q Ratios
Inhaled nitric oxide is an inhaled pulmonary vasodilator with an extremely short half that is used to improve pulmonary blood flow in area that are receiving ventilation.
It optimizes V/Q mismatch and also reduces pulmonary blood pressures.
What is the relationship between frequency, wavelengths, resolution and penetration in terms of ultrasound quality?
Higher frequency (shorter wavelengths) means better resolution, but worse penetration.
Lower frequency (longer wavelengths) gives better penetration but sacrifices resolution.
What are the 3 components of resolution of ultrasound physics?
Resolution is actually a very complex concept and is split into:
- Axial resolution
- Temporal resolution
- Lateral resolution
Define the 3 terms of resolution (Ultrasound Physics)
Axial resolution
Axial resolution is a function of the probe frequency and pulse width and represents the resolution along the vertical projection of the ultrasound beam. Resolution is improved with higher frequency, lower wavelength, and shorter pulse width.
Define the 3 terms of resolution (Ultrasound Physics)
Lateral resolution
Lateral resolution is the resolution along the horizontal axis of the ultrasound image and is a function of the beam formation. The image has both and near and far field.
The near field is columnar in shape, the length of which increases with higher frequency.
The far field results in a divergence of the beam and blurring of the ultrasound image produces.
Divergence increases with lower frequency and wider ultrasound probes.
# Define the ultrasound physics term: Temporal Resolution
Temporal resolution is the ability of the probe to differentiate moving objects in time and is the “frame rate” of the ultrasound image.
With decreasing scan depth, temporal resolution improves.
What does Antithrombin 3 inactivate?
Antithrombin III inactivates multiple coagulant factors, most notably thrombin (factor II), factor Xa, and other factors in the intrinsic pathway (see figure below)
What is different about enoxaparin vs. UFH in terms of its mechanism?
Enoxaparin similarly binds and enhances the effects of AT3. However, the enoxaparin-induced conformational change of AT3 makes enoxaparin preferentially inhibit factor Xa
When is it reasonable to monitor enoxaparin with labs? (What population)
Monitoring may be recommended in patients with extreme BMIs (high or low), renal impairment, or in pregnant patients.
What is the basic pathophysiology of Malignant Hyperthermia?
Malignant hyperthermia-susceptible patients have RYR1 defects that, in the presence of a triggering agent (succinylcholine or any volatile anesthetic)
Cause prolonged opening of the channel which leads to sustained muscle contraction.
This produces a generalized hypermetabolic state characterized by increased CO2, lactate, and heat production which can progress to muscle cell breakdown and leads to hyperkalemia*, *rhabdomyolysis*, and their sequelae (*arrhythmias*; *liver, kidney, and other end-organ damage, and death).
In a suspected MH patient, what must be used in order to reduce/prevent damage to the kidneys?
Diuretics and Mannitol (Keep UOP 1-2 mL/kg/hr)
CK levels will rise and can cause myoglobinuria
Each 20 mg Vial of Dantrolene contains 3 grams of Mannitol
In a suspected MH patient, what is your dose of Dantrolene?
What is the proposed mechanism of Dantrolene?
Dose for Crisis: IV: Initial: 2.5 mg/kg*; monitor patient continuously and give repeat doses of *1 mg/kg* until symptoms subside or a *cumulative dose of 10 mg/kg is reached
MOA: Acts directly on skeletal muscle by interfering with release of calcium ion from the sarcoplasmic reticulum; prevents or reduces the increase in myoplasmic calcium ion concentration that activates the acute catabolic processes associated with malignant hyperthermia
What are the 4 most common MAOI (Mono-amine oxidase inhibitors)?
- Isocarboxazid
- Phenelzine
- Selegiline
- Tranylcypromine
What are the signs and symptoms of Serotonin Syndrome?
What is the most common criteria (name)?
- Spontaneous clonus
- Inducible clonus plus agitation or diaphoresis
- Ocular clonus plus agitation or diaphoresis
- Tremor plus hyperreflexia
- Hypertonia plus temperature > 38 °C plus ocular clonus or inducible clonus
Hunter Toxicity Criteria
Serotonin syndrome results from coadministration of multiple serotonergic medications. It results in tachycardia, clonus, hyperreflexia, ataxia, and confusion.
What are some S/S of Neuroleptic Malignant Syndrome?
(Hint: What do they have to take? What is S/S? Course? Muscle Tone, Reflexes, Mydriasis)
Neuroleptic malignant syndrome occurs in patients taking antipsychotic medication. It is characterized by muscle rigidity and altered consciousness. Both first-generation neuroleptic medications*, such as haloperidol, and *newer atypical antipsychotics have been implicated in neuroleptic malignant syndrome.
What is the treatment for serotonin Syndrome?
- Discontinue serotonergic agents (Fent, SSRI, Ondansetron)
- Supportive care
- Benzos (Diazepam 10-20 mg IV
- Cyproheptadine (Serotonergic antagonist) 12 mg PO and repeat 2 mg Q2H (Max of 32 mg / day)
- Dexmedeotmidine
- Hyperthermia (If severe, intubate sedate and paralyze)
- Chlorpromazine (Phenothiazine with anti-serotonergic effects 50-100 mg IM
What is the treatment for neuroleptic malignant syndrome?
- Agitation should be controlled with Benzodiazepines
Lorazepam 2 mg IV q5 min until agitation and muscle rigidity resolves
- Supportive/Fluid resuscitation
- Cooling measures
- Intubation and paralysis for severe cases, chest wall rigidity or respiratory failure
Use NON-DEPOLARIZING paralytic agent
What is the glucocorticoid, mineralcorticoid potency and duration of action of:
Hydrocortisone
Prednisone
Prednisolone
Methylprednisolone
Dexamethasone
Fludrocortisone
Hydrocortisone 1, 1, 8-10 hours
Prednisone 4, 0.8, 18-36 hours
Prednisolone 4, 0.8, 12-26 hours
Methylprednisolone 5, 0.5, 18-36 hours
Dexamethasone 25-30, 0, 36-54 hours
Fludrocortisone 10, 120, 18-36 hours
Can antiemetic doses of dexamethasone be used for adrenal suppression?
8 mg of dexamethasone is equivalent to 200 mg of hydrocortisone and will suffice to prevent adrenal insufficiency with most commonly performed surgeries
Why don’t we use fludrocortisone for perioperative stress dose steroids?
Fludrocortisone is a potent mineralocorticoid. Even in patients with symptomatic adrenal suppression, treatment with fludrocortisone is not recommended since most of the problems from adrenal suppression are secondary to both mineralocorticoid and glucocorticoid deficiency and thus both need to be supplemented.
What is the agent of choice for treating adrenal suppression during stressful surgeries and why?
Hydrocortisone is the agent of choice for treating adrenal suppression during stressful surgeries because it has a 1:1 glucocorticoid: mineralocorticoid effect. However, most current literature suggests that dexamethasone alone is appropriate for prophylaxis in patients with possible secondary adrenal insufficiency (e.g. due to steroid use).
When is mineralcorticoid prophylaxis appropriate?
Mineralocorticoid prophylaxis is most appropriate for patients with primary adrenal insufficiency (unrelated to chronic steroid use).
Draw the Frank Starling Curve.
What is on the X axis?
What is on the Y axis?
What are the 3 classes of medicines used to treat?
X axis = Cardiac Output
Y axis = EDV (Of the LV)
Classes:
- Diuretics
- Ionotropic agents
- Vasodilators
Compare the saturated vapor pressure of isoflurane, sevoflurane, and desflurane.
Sevoflurane = 157
Isoflurane = 240
Desflurane = 669
Morphine Metabolites:
What are they?
What is primary?
What is active?
What is most potent?
What are the effects of each?
1. Morphine - 6 - Glucuronide (Primary active metabolite)
100 fold potent, yet (CAVEAT) exhibits an equal or decreased affinity for mu-opioid receptors. Its increased potency, however, can lead to significant respiratory depression in renal failure due to accumulation from delayed excretion.
2. Morphine - 3 - Glucuronide (Minority inactive metabolite)
Nearly 300 fold lower affinity for the μ-receptors but it may have neuroexcitatory effects; myoclonus and allodynia are seen after large doses.
What are the 3 medication classes and specific medications used for fibromyalgia?
- Tricyclic antidepressant (e.g. amitriptyline, nortriptyline)
- Serotonin-norepinephrine reuptake inhibitor (e.g. duloxetine aka Cymbalta, milnacipran, venlafaxine)
- Alpha-2/delta calcium channel modulator (e.g. gabapentin, pregabalin)
What oxygen tension is required in the full term infant to close the ductus arteriosus?
Oxygen is the most influential factor in the closure of the ductus in the full-term infant.
The ductus arteriosus is usually functionally closed by the second day of life. In a full-term infant, a PaO2 of about 50 mmHg constricts the vessel.
Oxygen tension is not as influential in closing the preterm neonate’s ductus arteriosus
Draw the 4 chamber echo view
What is the distribution of coronary blood flow
RCA = Right heart and basal septum
Middle septum = RCA or LAD
Apical septum = LAD
Lateral wall = LAD or Circumflex
Draw the 2 chamber echo view
What is the distribution of coronary blood flow
Inferior Wall (Left) = RCA
Anterior Wall (right) = LAD
Draw the Long Axis of the LV view
What is the distribution of coronary blood flow
Posterior wall (left) = RCA or Circumflex
Anteroseptal wall (right and base) = LAD
Draw the echo view of transgastric Short Axis
What is the distribution of coronary blood flow
Notice, the distribution depends on coronary dominance
Rank the Bioavailability of Midazolam depending of the route
“I SMiLN RO“
- IV 100%
- SQ 96%
- IM 85-87%
- SL / Buccal 74.5%
- Intranasal 50-83%
- Rectal 18-52%
- Oral 15-52%
A full Oxygen E-cylinder contains how many Liters* and *pressure?
~2000 psi (1900- 2200)
660 Liters
A full Nitrous Oxide E-cylinder contains how many Liters and pressure?
1590 Liters
745 psg
A full Carbon Dioxide E-cylinder contains how many Liters and pressure?
1590 Liters
838 psi
A full AIR E-cylinder contains how many Liters and pressure?
(Appoximately Same as Oxygen)
1900 psi
620 Liters
A full Helium E-cylinder contains how many Liters and pressure?
500 Liters
1600 psi
What are the colors for a CO2 E cylinders in the United States?
Gray
What are the colors for a Helium E cylinders in the United States?
Brown
Draw a Normal Pressure Volume Loop indicating:
Cardiac cycle
X Axis
Y Axis
LVEDV, LVESV, CPP, AoDP, LVESP, AoSP, Contractility
X axis = LV Volume
Y Axis = LV pressure
Draw the Pressure Volume Loop for Milrinone
What is the treatment for Myxedema Coma?
-
Thyroid Replacement
- Levothyroxine preferred (TSH secretion regulation and conversion to T3)
- Liothyronine (most potent form) can precipitate myocardial ischemia - Hydrocortisone (5-10%) of patients can have adrenal insufficiency
The lumbar plexus gives rise to what 3 major nerves (regarding blocks)?
The sacral plexus gives rise to what 2 major nerves (regarding blocks?
The lumbar plexus gives rise to the femoral nerve, obturator nerve, and lateral femoral cutaneous nerve.
The sacral plexus gives rise to the posterior cutaneous nerve of the thigh and sciatic nerve.
The sciatic nerve provides cutaneous innervation to what locations?
The sciatic nerve provides cutaneous innervation to the posterior thigh and all of the leg and foot below the knee, except for a medial strip supplied by the saphenous nerve.
At the popliteal fossa, the sciatic nerve divides into what two nerves?
Tibial and common peroneal nerves
What are the 3 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.
Hypokalemic Periodic Paralysis
Inheritance Pattern?
Autosomal Dominant
What are the triggers for hypokalemic periodic paralysis?
Strenuous exercise
Excitement
High sodium
Carbohydrate meals
Fibrinolysis:
What is the substrate, enzyme and byproduct of clot breakdown?
Fibrinolysis (fibrin breakdown), a normal hematologic activity that leads to removal of thrombus when endothelium heals, is conducted mostly by the enzyme plasmin, the product of cleavage of plasminogen by tissue plasminogen activator (tPA).
Why do we use aminocaproic acid for Cardiopulmonary Bypass cases?
Fibrinolysis can be excessive and lead to bleeding, for example after cardiopulmonary bypass (cardiopulmonary bypass causes the endothelium to release tPA).
Currently available antifibrinolytic agents (aminocaproic acid and tranexamic acid) are analogs of the amino acid lysine, and as such they competitively inhibit the binding of plasmin(ogen) lysine binding sites to the lysine residues in fibrin.
In other words, they prevent the formation of the ternary complex mentioned above.
Antifibrinolytic agents have been shown to reduce total perioperative blood loss and the number of patients transfused in major cardiac, orthopedic, or liver surgery. Currently, the ASA guidelines give a recommendation to “use” such agents for prevention of bleeding in patients undergoing cardiopulmonary bypass, but only of “consider using” for other indications.
Other than low fibrinogen concentations, what are the two other acceptable indications for cryoprecipitate?
fibrinolysis, massive transfusion, and low fibrinogen concentration (definitions of “low” vary and are typically higher in pregnancy).
What is the mechanism of action of TXA (Tranexamic Acid)?
- Competitively inhibits activation of plasminogen (via binding to the kringle domain), thereby reducing conversion of plasminogen to plasmin (fibrinolysin), an enzyme that degrades fibrin clots, fibrinogen, and other plasma proteins, including the procoagulant factors V and VIII.
- Directly inhibits plasmin activity, but higher doses are required than are needed to reduce plasmin formation.
Going from medial to lateral, which is the correct order of neurovascular structures in the antecubital fossa?
Median Nerve, Brachial Artery, Radial Nerve
What is the largest nerve in the body unprotected, and thus is most injured during surgeries?
It is the largest nerve in the body that is not protected by muscle or bone, is the ULNAR NERVE
The ulnar nerve travels down the medial aspect of the upper and lower arm. It could be considered the most medial neurovascular structure in the arm at the level of the elbow, however at the level of the antecubital fossa it courses posterior to the medial epicondyle of the humerus
What are the components of the MELD Score?
MELD: “I Crush Several Beers Daily” for INR, creatinine, sodium, bilirubin, dialysis
“C DIBS” on MELD
How do opioid, barbiturate, and other sedative-hypnotic medication administration shift the Ventilatory response curve?
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.
How do Volatile anesthetics shift the ventilatory response curve?
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.
How does hypoxemia, acidosis, surgical stimulus and increased ICP shift the ventilatory response curve?
Surgical stimulus and heightened states of arousal (e.g. fear or anxiety) cause hyperventilation. This typically causes a leftward shift and increased slope of the carbon dioxide ventilatory response curve (VRC).
General Anesthesia resembles:
What EEG findings?
General anesthetic effects on the brain most resemble the naturally occurring non-rapid eye movement (NREM) sleep pattern on EEG (slow-frequency, large-amplitude).
There is a transition from the low amplitude, fast-frequency pattern of wakefulness, to the high amplitude, slow-frequency EEG of NREM sleep.
Blood PaCO2 is measured how?
Blood PCO2 is measured by a Severinghaus electrode using a method that builds upon the pH electrode mechanism.
Carbon dioxide from the blood sample equilibrates across a semipermeable membrane with a bicarbonate solution.
The reaction generates H+ ions and the PCO2 is determined by the degree of pH change resulting from the H+ ion generation.
Blood PaO2 is measured how?
Blood PO2 is most commonly directly measured by a Clark electrode which detects the amount of current that flows between the two electrodes (amperometric).
Oxygen from the blood sample diffuses across a semipermeable membrane and is reduced at the cathode, resulting in a reaction that produces a measurable current that is directly proportional to the PO2.
What two bones make up the hard palate?
The hard palate (maxilla and palatine bones) forms the anterior two-thirds of the roof of the mouth.
(The palatine bone is highlighted in green in the image)
The tongue is anchored to the mandible by what muscle?
The tongue is anchored to the mandible by the genioglossus muscle.
When sleeping or under general anesthesia, the tongue often displaces posteriorly into the oropharynx causing upper airway obstruction
Where does the spinal cord and dural sac end in both adults and infants?
In adults, the spinal cord ends at about L1-L2 (conus medullaris) and the dural sac ends at about S1-S2
In an infant, these landmarks are shifted slightly caudad with the spinal cord ending at L3-L4 and the dural sac terminating at S3-S4.
The lateral antebrachial cutaneous nerve is a branch of the What nerve?
It provides cutaneous innervation to what areas?
It arises from what nerve roots?
What block is needed to block it?
The lateral antebrachial cutaneous nerve is a branch of the musculocutaneous nerve.
It provides cutaneous innervation to the lateral half of the forearm.
It arises from C5-C6 and therefore is part of the brachial plexus and would most likely be blocked by a supraclavicular nerve block.
Quantitatively, what is a concerning change in SSEP monitoring?
SSEPs are quantified by the amplitude of the signal generated and the latency of the signal, which is the time it takes for the impulse to reach the cortex. Anything that decreases the amplitude or increases the latency is concerning. This could be from direct damage to the nerve or ischemic insult.
A clinically significant decrease in amplitude is 50% from baseline and a 10% increase in latency.
Draw a graph comparing the PVR compared to lung volumes
In normal healthy adults, PVR is lowest when breathing at normal tidal volumes, with a nadir at functional residual capacity (FRC).
Increasing or decreasing lung volumes beyond FRC and normal tidal volumes results in an increase in PVR, creating a U-shaped curve, illustrated below.
This general relationship exists for both normal breathing and positive-pressure breathing.
An OB Anesthesiology attending asks you:
How does a spinal work to control pain? What is your response?
Neuraxial fentanyl results in rapid onset of analgesia primarily through activation of mu receptors in the substantia gelatinosa in the dorsal horn of the spinal cord.
Opioids activate G-protein coupled inhibitory receptors both pre and postsynaptically to inhibit the release of excitatory neurotransmitters (presynaptic) and hyperpolarize postsynaptic neurons to inhibit neuronal transmission.
In the brain, exogenous and endogenous opioids work in the area of the periaqueductal gray matter of the midbrain and rostral ventromedial medulla and modulate descending inhibitory pain pathways.
Systemic administration, ascent in the CSF to the brain (hydrophilic opioids such as morphine), and absorption from neuraxial administration (primarily with lipophilic opioids such as fentanyl) activate these descending inhibitory pathways.
Neuraxial administration of opioids results in analgesia primarily by action in the dorsal horn of the spinal cord in the substantia gelatinosa where they inhibit release of excitatory neurotransmitters such as substance P and glutamate and inhibit afferent neural transmission to the brain from incoming peripheral pain neurons.
Transtracheal injection of local anesthetic will block what nerve?
Transtracheal injection of local anesthetic will block the recurrent laryngeal nerve.
How does respiratory rate affect the degree of citrate toxicity?
Hypoventilation does not increase the risk of toxicity; the reverse is true.
Hyperventilation increases the risk of citrate toxicity in a certain subset of patients because it causes a decrease in ionized calcium ions.
This is why signs of hypocalcemia can be seen in patients who have anxiety attacks and hyperventilate. In certain patients, hyperventilation will result in ionized calcium ions binding to proteins. Since citrate toxicity is actually due to hypocalcemia, anything that decreases the ionized calcium ions will increase the risk for citrate toxicity.
What is the gold standard for ICP monitoring?
Elevated Intracranial Pressure
Gold Standard:
A ventriculostomy catheter is the most cost-effective, accurate, and reliable method of monitoring intracranial pressure (ICP) and is currently the gold standard for ICP measurement.
It is also very useful in that it provides a way to drain cerebrospinal fluid (CSF), and samples for lab analysis.
What are the two types of cutting needles that increase PDPH risk?
What are the two non-cutting needles that cause less PDPH?
Pencil-point needles such as the Sprotte and the Whitacre (non-cutting) have less risk than a cutting needle such as the Quincke and Touhy (cutting)
What is the mechanism of action of Digoxin?
Digoxin exerts these effects through inhibition of the sodium-potassium adenosine triphosphatase (Na/K ATPase) pump that is located in the myocardium.
This inhibition of this crucial transporter in the myocardial cell membrane results in an increase in the concentration of intracellular sodium.
This increased sodium in the myocyte decreases the activity of another membrane protein known as the sodium-calcium exchanger
Because this molecule will normally extrude a single calcium molecule from the intracellular cytoplasm in exchange for bringing three sodium molecules into the intracellular space, and increased intracellular sodium concentration will tend to increase the concentration of calcium within cardiac myocytes.
This increased intracellular calcium is the primary means by which digoxin exerts its clinical effect.
What is the best anatomical location to achieve a lumbar sympathetic plexus block?
Correct needle position at the lumbar sympathetic plexus is at the anterolateral aspect of lumbar vertebral bodies (L1-L5). The best approach is just cephalad to the middle of the L3 vertebral body due to the highest rate of successful block.
How does solubility of CO2 change with hypothermia? (Affects on pH and PaCO2)
The solubility of CO2 will increase as the patient’s temperature decreases, resulting in a relative respiratory alkalosis in a hypothermic patient as the partial pressure of CO2 above the solution decreases as more CO2 is dissolved in the serum.
This respiratory alkalosis (pH high and PaCO2 low) is not apparent when the arterial blood sample is rewarmed to 37 degrees Celsius and it is common for the arterial blood gas to appear normal.
What effect is the process of oxygen binding to hemoglobin and displacing carbon dioxide, which will result in a downward shift in the carbon dioxide dissociation curve?
The Haldane effect is the process of oxygen binding to hemoglobin and displacing carbon dioxide, which will result in a downward shift in the carbon dioxide dissociation curve. This facilitates the removal of carbon dioxide from the body.
What effect is the process of carbon dioxide binding to hemoglobin causing oxygen to be displaced, which will result in a rightward shift of the oxygen-hemoglobin dissociation curve?
The Bohr effect is the process of carbon dioxide binding to hemoglobin causing oxygen to be displaced, which will result in a rightward shift of the oxygen-hemoglobin dissociation curve.
What are the different waves seen in EEG monitoring?
TrueLearn Insight : Order in which frequency decreases and amplitude increases: BAT Drink
Beta wave: > 14 Hz, low amplitude
Alpha wave: 8-13 Hz, high amplitude
Theta wave: 4-7 Hz, high amplitude
Delta wave: 0.5-4 Hz, maximum amplitude
Gamma waves have a frequency of 25 to 100 Hz and are thought to be involved in cortical processing.
Beta waves are typically > 14 Hz in frequency and are usually found in patients who are concentrating, or sometimes in patients under anesthesia. (or sedation)
Alpha waves have a frequency of 8 to 13 Hz & found in awake patients resting with their eyes closed.
Theta waves have a frequency of 4 to 7 Hz and are also associated with sleep and sedated states.
Delta waves have a frequency of 0.5 to 4 Hz and are found in patients under deep sleep, sedation or general anesthesia.
What is seen on the capnogram here?
A “double peak” appearance is commonly observed with capnography in patients with chronic obstructive pulmonary disease (COPD) who have received a single lung transplant, reflecting the difference in function of the transplanted and native lung.
A capnogram from a patient with a single lung transplantation due to chronic obstructive pulmonary disease will show a “double peak” pattern, reflecting the difference in function between the healthy transplanted lung and the diseased native lung. The rapid initial exhalation from the healthy, transplanted lung produces the first peak, while the slower rate of rise of exhaled carbon dioxide from the diseased, obstructed lung produces the second peak.
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.
What is shown here on the ETCO2 capnogram?
An incompetent inspiratory valve allows exhaled gas (containing CO2) to enter the inspiratory limb of the breathing circuit during expiration.
Therefore, the CO2-containing gas is inspired by the patient during the following inspiration. This extends the expiratory alveolar plateau (phase 3–4).
A decrease in CO2 occurs after the extended plateau and represents the sampling of CO2-free gas that arrived from further proximal in the inspiratory limb. Thus the inspiratory downstroke (phase 4–1) is significantly blunted and the inspiratory phase is shortened (see Figure 3). During the latter portion of inhalation, the CO2 concentration may or may not reach zero, depending on fresh gas flow (FGF).
What ETCO2 tracing is seen here?
Incompent Expiratory Valve
Capnogram of incompetent expiratory valve. The capnograph shows a markedly elevated inspiratory segment that does not return to zero, representative of rebreathing of CO2. Over time, the ETCO2 will rise, but the shape of the tracing is otherwise essentially normal.
Rank the modalities to detect Venous Air Embolisms in terms of most to least sensitive.
MOST
TEE
Precordial Doppler
Pulmonary Artery Cathter
Transcranial Doppler
Moderate
ETN2
ETCO2
Low
Oxygen Saturation
Diect Visualization
Esophageal Stethoscope
ECG
List all the factors that cause a leftward shift on the hemoglobin-oxygen dissociation curve?
CO poisoning
Hypothermia
Hypocapnia
Alkalemia
Reduced concentrations of 2,3-bisphosphoglycerate (an enzyme formed during anaerobic metabolism which readily binds deoxygenated hemoglobin)
Hypophosphatemia
For a femoral nerve block, local anesthetic is deposited in between what layers?
Local anesthetic can then be deposited beneath the fascia iliaca or between the two layers of fascia iliaca containing the femoral nerve.
While performing an ultrasound-guided femoral nerve block, a “pop” through the fascia iliac is felt while advancing the needle just prior to the successful deposition of local anesthetic. You will have a sudden change in resistance once in this space.
