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ABA Basic Exam > Basic exam content > Flashcards

Basic exam content Flashcards

1
Q

AcH receptor upregulation and NMBA

A

Upregulation results in increased number of immature AcH receptors (fetal subunit) at NMJ that extend into adjacent membranes

  • Increased sensitivity to AcH and Suxx
  • Decreased sensitivity/increased resistance to NDNMBA (why? more receptors need to be antagonized)
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2
Q

ACLS treatment for symptomatic bradycardia

A

1st line: atropine, transcutaneous pacing

2nd line: epinephrine, dopamine

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3
Q

Active cardiac conditions that require perioperative evaluation

A

Unstable coronary syndrome

  • acute MI (<7 days old)
  • recent MI (7-30 days old)
  • unstable angina

Decompensated heart failure

  • NYHA class IV
  • new onset HF

Symptomatic arrhythmias

  • mobitz type II AV block
  • 3rd degree AV block
  • Afib with RVR
  • symptomatic bradycardia

Severe valvular disease

  • severe aortic stenosis (mean pressure gradient >40 mmHg, aortic valve area <1.0 cm2
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4
Q

Allergen associated with latex allergy

A

Banana

Avocado

Kiwi

Pineapple

Mango

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5
Q

Alternative hypothesis (Ha)

A

States a difference DOES exist between the variables being tested

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6
Q

Alveolar gas equation

A

PAO2 = [(Patm - PH20) *FiO2] - (PaCO2/0.8)

Patm = 760 mmHg at sea level

PH20 = water vapor pressure = 47 mmHg at 37C

Increased Patm and FiO2 increase PAO2

Decreased PH2O and PACO2 decrease PAO2

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7
Q

Ambient lights effect on pulse oximetry

A

Increase in ambient light exposure increases DC signal, creating a poor pulse oximeter waveform, limiting its accuracy

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8
Q

Amiloride: MOA, side-effects

A

Potassium-sparing diuretic that acts on distal collecting ducts leading to hyperkalemia and sodium excretion.

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9
Q

Amount of fibrinogen in cryoprecipitate

A

200 mg/unit

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10
Q

Arterial waveforms: central (aorta) vs. peripheral

A

Peripheral waveforms:

Steeper upstroke

Higher systolic peak

Later dicrotic notch

Lower end-diastolic pressure

Wider pulse pressure (diff btw SBP and DBP)

60msec delay in systolic upstroke

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11
Q

ASA classification of physical status: 2

A

Mild systemic dz ex: well controlled DM, HTN, asthma (on inhalers), PREGNANCY, SMOKERS W/O COPD

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12
Q

ASA classification of physical status: 3

A

Severe systemic dz (no immediate threat to life) ex: DM w/ complications (retinopathy), asthma w/ hospitalizations, MI or CVA >6 mo ago, STABLE ANGINA, controlled CHF, ESRD on dialysis

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13
Q

ASA classification of physical status: 4

A

Severe systemic dz with constant threat to life ex: symptomatic CHF, MI or CVA <6 mo ago, UNSTABLE ANGINA, ESRD NOT on dialysis

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14
Q

ASA classification of physical status: 5

A

Moribund pt who won’t survive without surgery ex: septic shock, multi-organ failure, ICH with mass effect

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15
Q

ASA classification of physical status: 6

A

Declared brain dead, organ donor

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16
Q

At what point is cartilage totally absent from the airway wall?

A

Terminale bronchioles

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17
Q

Bainbridge reflex

A

Increases HR by inhibiting parasympathetic activity when stretch receptors located in the right atrial wall sense increased pressure

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18
Q

Benefit of additing opioid to epidural solution

A
  • able to use more dilute LA
  • prolongs duration of analgesia
  • improves quality of sensory blockade
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19
Q

Biggest predictor of difficult intubation in morbidly obese pts?

A

Thick neck circumference (>40 cm)

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20
Q

Boyle’s Law

A

Shows effect of change in volume or pressure when temp remains constant

P1 V1 = P2 V2

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21
Q

Brachial artery catheterization risks

A

#1: vessel thrombosis

Infection

Median nerve injury

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22
Q

Burn pts and NMBA: how is dosing affected, why?

A

Burn pts exhibit resistance to NDNMBA resulting in increased dosing requirements due to upregulation of AcH receptors and increase in plasma protein binding

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23
Q

Calculate minutes until hypoxemia

A

Assumptions:

  1. oxygen consumption in an adult ~3-4 mL/kg/min
  2. FRC 30 mL/kg

min. until hypoxemia = [FRC/O2 consumption] x %O2 in FRC

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24
Q

Cardiovascular complications due to use of ketamine in critically ill patients

A

Ketamine is a direct myocardial depressant and smooth muscle relaxant but also blocks neuronal reuptake of circulating catecholamines, thereby leading to elevation of BP, HR, CO and myocardial oxygen consumption.

However, critically ill patient’s who have depleted their catecholamine stores or lack the ability to compensate via the sympathetic nervous system will experience decreased BP and CO.

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25
Q

Cardiovascular effects due to laparoscopic surgery

A

Increased cardiac filling due to increased intrathoracic pressure

Arrhythmias

Decreased venous return due to vena cava compression

Decreased EF

Decreased renal blood flow (results in decreased UOP 2/2 increased ADH secretion)

Decreased splanchnic perfusion

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26
Q

Cardiovascular effects of desflurane

A

Decreases arterial pressure by decreasing afterload

Increases HR, especially after quick concentration change

Dose-dependent depression of myocardial fxn

Maintains CO

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27
Q

Cardiovascular effects of ketamine

A

Direct myocardial depressant and smooth muscle relaxant. HOWEVER, also decreases neuronal reuptake of circulating catecholamines. Therefore, net result is:

  • elevated BP
  • elevated HR
  • elevated CO
  • increased myocardial oxygen consumption
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28
Q

Cardiovascular effects of Propofol

A

Propofol decreases sympathetic activity, therefore…

  • Decreased SBP and DBP w/o increase in HR (CO, SV and SVR all decrease lowering BP while propofol inhibits baroreceptor response, therefore no reflexive increase in HR occurs)
  • Myocardium depression (due to altered intracellular Ca2+ balance/influx)
  • Both arterial and venous vasodilation
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29
Q

Causes of a sudden drop in EtCO2

A

Cardiovascular collapse (decreased CO)

VAE

PE

Kinked/dislodged ETT

Esophageal intubation

Sample line disconnect

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30
Q

Causes of BOTH elevated peak inspiratory pressure and plateau pressure

A
  • Intrinsic pulmonary dz
  • Ascites
  • Insufflation
  • Tension PTX
  • Trendelenburg positioning
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31
Q

Causes of decreased mixed venous oxygen saturation (SvO2)

A
  • Increased oxygen consumption (fever, shivering)
  • Decreased CO (cardiogenic shock)
  • Decreased [Hgb] (anemia)
  • Decreased arterial oxygen saturation (methemoglobinemia)

Fick Equation:

SvO2 = SaO2 - [VO2/(CO x Hgb x 1.36)]

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32
Q

Causes of elevated peak inspiratory pressures with unchanged plateau pressure.

Why?

A
  • Bronchospasm
  • Kinked ETT
  • Airway secretions
  • Mucous plug

Peak inspiratory pressures directly proportional to changes in airflow resistance, while plateau pressure changes vary with change in lung compliance/elastic changes.

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33
Q

Causes of increased mixed venous oxygen saturation (SvO2)

A
  • Inadequate regional blood flow (PVD)
  • Decreased VO2 (sepsis, CN toxicity, hypothermia)
  • Increased SaO2 (L to R intracardiac shunt, AV fistula)
  • Increased [Hgb] (polycythemia)

Fick Equation:

SvO2 = SaO2 - [VO2/(CO x Hgb x 1.36)]

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34
Q

Causes of non-anion gap acidosis

A

FUSEDCARS:

  • Fistula
  • Ureteral diversion
  • Saline administration
  • Endocrine dfxn
  • Diarrhea
  • Carbonic anhydrase inhibitors (acetazolamide)
  • Ammonium chloride (TPN component)
  • RTA
  • Spironolactone
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35
Q

Causes of prolonged succinylcholine duration of action

A
  1. Pseudocholinesterase deficiency
  2. Liver dz (why? pseudocholinesterase produced by liver)
  3. Pregnancy
  4. Malnutrition
  5. Malignancy
  6. Hypothyroidism
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36
Q

Causes of rebreathing CO2

A

Depleted CO2 absorbent

Dysfunctional circuit valve

Low FGF

Improper calibration of bellows

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37
Q

Central action of opioids in CNS

A
  • Activate descending inhibitory pain pathway via inhibition of GABA receptors in the brainstem
  • Provide analgesia via mu1 receptors in periaqueductal gray matter, locus ceruleus and nucleus raphe magnus
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38
Q

Characteristics of depolarizing blockade

A
  1. No fade in response to repetitive stimuli
  2. No amplification in force of subsequent muscle contractions after period of high-frequency stimulus (tetany)
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39
Q

Characteristics of non-depolarizing blockade

A
  1. Progressive decrease (fade) in response to repetitive stimuli
  2. Potentiation of evoked responses with high-frequency stimulation (tetany) = increased amplitude and decreased fade of response
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40
Q

Characteristics of Propofol-infusion syndrome

A

Acute refractory bradycardia

Severe metabolic acidosis

Cardiovascular collapse

Rhabdomyolysis

Hyperlipidemia/hypertriglyceridemia

Renal failure

Hepatomegaly

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41
Q

Charle’s Law

A

Shows effect of change in V or T when pressure remains constant

V1 / T1 = V2/ T2

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42
Q

CNS effects of ketamine

A
  • increases CMRO2
  • increases CBF (therefore, increases CBV)
  • elevates ICP
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43
Q

CNS effects of meperidine. Why?

A

Tremors

Muscle twitches

Seizures

Meperidine is a synthetic opioid, acts on mu-receptors, metabolized in liver to normeperidine- t1/2 15-30 hrs, no mu-receptor activity but is a CNS STIMULANT.

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44
Q

CNS effects of opioids

A
  • reduce MAC of inhaled anesthetics
  • normeperidine-induced seizures
  • reduce cerebral metabolic oxygen requirement
  • reduce CBF
  • reduce ICP (except in TBI!)
  • opioid induced respiratory depression and associated mydriasis
  • stimulate area postrema in brainstem leading to N/V
  • interfere with serotonin uptake causing serotonin syndrome
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45
Q

CNS effects of propofol

A
  • hypnosis via agonism at beta subunit of GABA-A receptor and inhibition of glutamate binding site on NMDA receptors
  • decreases IOP
  • decreases CMRO2 and CBF, leading to decrease ICP
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46
Q

Common causes of anion-gap metabolic acidosis

A

MUDPILES

Methanol (formic acid)

Uremia

DKA

Paraldehyde

Iron, Isoniazid

Lactic acidosis

Ethanol

Salicylates

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47
Q

Common drugs associated with Serotonin syndrome

A
  • Levodopa, Carbidopa-levodopa
  • SSRI (citalopram, fluoxetine, sertraline)
  • SNRI (duloxetine, venlafaxine)
  • Dopamine-NE reuptake inhibitor (bupropion)
  • Trazodone
  • TCAs (amitriptyline, clomipramine)
  • Valproate, Carbamezepine
  • St. John’s Wort
  • Dextromethorphan
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48
Q

Common trauma related causes of HoTN

A
  • # 1 = hemorrhage
  • Abnl cardiac pump fxn (myocardial contusion, tamponade, coronary artery dissection, valve injury)
  • PTX
  • Hemothorax
  • Spinal cord injury
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49
Q

Complications associated with succinylcholine

A
  1. bradycardia, asystole (esp. in children)
  2. fasciculations, myalgias
  3. elevated IOP
  4. elevated ICP
  5. elevated serum K+
  6. rhabdomyolysis/fatal hyperkalemia in children with muslce dystrophies
  7. malignant hyperthermia (associated with concomittant IA use)
  8. masseter muscle spasm
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50
Q

Complications of neuraxial anesthesia

A

Hypotension

Bradycardia

Postdural puncture HA

Epidural hematoma (reqs emergent evacuation)

Infx- epidural abscess, meningitis

Urinary retention

Transient neurologic sx- spinal only, occurs 24hrs after block wears off, causes severe buttock pain but no sensory or motor deficits

LAST

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51
Q

Complications of sodium bicarbonate administration

A
  • Left shift of oxygen dissociation curve due to increasing pH, leading to tissue hypoxia, subsequent anaerobic metabolism and worsening lactic acidosis
  • Depression of LV contractility, as sodium bicarbonate will transiently decreased serum ionized [calcium]; LV contractility is proportional to serum ionized [calcium]
  • Increased preload, as sodium bicarbonate is a hypertonic solution (~1,800 mOsm/L), leading to increased intravascular volume
  • Risk of elevated ICP and ICH, especially in infants, due to volume expansion in setting of sodium bicarbonate conversion to PCO2 leading to cerebral vasodilation
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52
Q

Conditions associated with latex allergy. Why?

A

Spina bifida

Urogenital syndromes

Frequent exposure to latex foley catheters and surgical equipment with latex

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53
Q

Consideration for pt undergoing retinal detachment surgery with use of SF6 (sulfur hexafluoride)

A

AVOID NITROUS OXIDE FOR 4 WEEKS! N2O can raise IOP by expanding air bubble.

SF6 used as intraocular gas during retinal detachment surgery.

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54
Q

Contraindications for cricoid pressure

A

Active vomiting

Unstable cervical spine

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55
Q

Contraindications of ketamine

A

Increased ICP

Increased IOP or open eye injury

ICM lesion

Ischemic heart disease

Vascular aneurysm

Psych hx, including PTSD, Schizophrenia

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56
Q

Contraindications of LMA

A

Unknown PO status (pt can aspirate around LMA)

Restrictive pulmonary dz (decreased chest wall compliance, LMA not intended for positive pressure ventilation)

Non-supine positioning, ie: lithotomy

Obesity

Pregnancy

Intra-abdominal procedures

Prolonged surgical time

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57
Q

Contraindications of nasotracheal intubation

A

Severe coagulopathy

High-dose systemic anticoagulation

Nasal pathologies or mass lesions

Infection of paranasal sinuses

Basilar skull fracture

TBI with CSF leak

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58
Q

Contraindications to electrical defibrillation

A
  • pulseless electrical activity (PEA)
  • asystole
  • VT with pulse and perfusable rhythm (once unstable, should receive cardioversion; only defibrillate once pulseless)
  • wet environment
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59
Q

Contraindications to sugammadex

A

Pts with allergy to cyclodextrins

Pediatric pts

ESRD

Reversal of agents other than rocuronium/vecuronium

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60
Q

Contraindications to use of EMLA cream

A

Allergy to amides (lidocaine, prilocaine)

Use of class III antiarrhythmics (amiodarone, sotalol, dofetilide)

Hx of congenital methemoglobinemia

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61
Q

Contraindications to use of N2O

A

Venous/arterial air embolism

PTX

Intestinal obstruction with bowel distention

Pneumocephalus

Pulmonary blebs

Intraocular procedures

Tympanic membrane procedures

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62
Q

Coronary artery perfusion of left ventricle

A

LAD, diagonals:

  • medial aspect anterior wall
  • anterior 2/3 septum
  • apex

Left circumflex, marginals:

  • anterior/posterior aspect of lateral wall

RCA:

  • medial posterior wall
  • posterior 1/3 septum
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63
Q

Critical side-effect of Naloxone administration

A

Pulmonary edema

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64
Q

CSF flow

A

Produced in lateral ventricles —> third ventricle via intraventricular foramina —> fourth ventricle via cerebral aqueduct —> subarachnoid space to surround brain and spinal cord

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65
Q

Cushing’s triad

A

HTN

Bradycardia

Respiratory changes

*sign of elevated ICP and impending uncal herniation.

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66
Q

CYP2CP metabolism

A
  • Phenytoin
  • Warfarin
  • Ibuprofen
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67
Q

CYP2D6 metabolism

A
  • Beta blockers
  • Amiodarone
  • Codeine
  • Tramadol, Fentanyl, Oxycodone
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68
Q

Effect of damage to Recurrent Laryngeal nerve, unilateral

A

Hoarseness

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69
Q

Ddx: Large R wave in lead V1

A
  1. Right ventricular hypertrophy
  2. Posterior wall MI
  3. WPW
  4. Muscular dystrophy
  5. Right atrial enlargement
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70
Q

Define critical pressure

A

The pressure required to liquefy a gas at its critical temperature.

Remember, critical temperature is the temperature above which no amount of pressure can convert a gas to liquid.

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71
Q

Define critical velocity

A

Critical velocity is the velocity at which flow turns from laminar to turbulent flow.

Critical velocity is dependent on:

  • radius of the tube (r)
  • viscosity (Π)
  • density (þ)
  • Reynolds number (k)

Critical velocity = kΠ ÷ þr

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72
Q

Definition mixed venous oxygen saturation, SvO2

A

Measure of peripheral tissue perfusion signified by %O2 bound to Hgb in blood returning to right atrium (blood captured from SVC, IVC, coronary sinus)

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73
Q

Definition of critical temperature

A

Highest temperature at which a gas can exist in liquid form

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74
Q

Definition of efficacy

A

Maximum effect produced by a drug.

Efficacy does not depend on dose.

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75
Q

Definition of neurogenic shock

A

Hypotension and bradycardia caused by the loss of vasomotor tone and sympathetic innervation of the heart as a result of functional depression of the descending sympathetic pathways of the spinal cord.

It is usually present after high thoracic and cervical spine injuries and improves within 3 to 5 days.

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76
Q

Definition of potency

A

Dose required to produce a given effect.

Related to receptor affinity. S

maller dose needed for given effect, the higher the potency.

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77
Q

Definition of viscosity

A

Resistance to flow. Also, internal friction between adjacent fluid layers sliding past each other. Increases based on opportunity for hydrogen bonding, components of fluid and molecular size.

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78
Q

Definition: Difficult endotracheal intubation

A

>3 attempts or >10 minutes

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79
Q

Definition: Difficult mask ventilation

A

Inability of unassisted anesthesiologist to maintain SpO2 >92% or prevent/reverse signs of inadequate ventilation.

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80
Q

Definition: General Anesthesia

A

GA occurs when pt loses consciousness and ability to respond purposefully, whether or not airway instrumentation occurs

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81
Q

Definition: Monitored Anesthetic Care

A

MAC = varying levels of sedation, analgesia, anxiolysis; provider must be prepared to convert to general anesthesia when necessary

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82
Q

Describe Alveolar-arterial gradient

A

A-a gradient measures pulmonary shunt to determine the efficacy of pulmonary oxygenation of arterial blood.

A-a gradient in healthy pt < 10mmHg

Normal gradient exist due to physiologic shunting through bronchial and coronary veins that drain deoxygenated blood directly into left heart.

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83
Q

Describe blood/gas coefficient

A

It is the ratio of the concentrations of a compound in one solvent to the concentration in another solvent at equilibrium.

The blood/gas partition coefficient describes how the gas will partition itself between the two phases (blood/alveoli) after equilibrium has been reached.

High solubility = more anesthetic needs to be dissolved = slower onset

MAC decreases as blood gas partition coefficient increases, generally speaking

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84
Q

Describe boiling point

A

Boiling point is reached when vapor pressure is in equilibrium with external ambient pressure exerted on liquid surface.

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85
Q

Describe cardiac side-effect of isoflurane

A

Isoflurane has been shown to dilate coronary arteries that can lead to coronary steal syndrome. Coronary steal refers to narrowed coronary arteries with collateral microvasculature that becomes bypassed leading to myocardial ischemia in that distribution.

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86
Q

Describe dampening of a system.

What are signs of increased dampening?

Name causes of system dampening.

A

Dampening refers to the decrease of signal amplitude that accompanies a reduction of energy in an oscillating system.

Signs of increased dampening include:

  • decrease in SBP
  • increase in DBP

In a pressure transducer system, most dampening arises from factors that decrease energy in the system:

  • friction between tubing and fluid within the tubing
  • 3-way stopcock
  • bubbles
  • clots
  • arterial vasospasm
  • large catheter size
  • narrow, long or compliant tubing
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87
Q

Describe “defibrillation”

A

During defibrillation, a RANDOMLY timed high-voltage electric current is discharged across two electrodes in attempt to SIMULTANEOUSLY DEPOLARIZE a large critical mass of myocardium. This would cause nearly all ventricular myocytes to enter their absolute refractory periods where no action potentials can be generated. At this point, the pacemaker with the highest automaticity (SA or AV node) will take control of ventricular pacing and contraction.

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88
Q

Describe dibucaine-resistant cholinesterase deficiency study

A
  • Examines pt serum in those with suspected genetic mutations in pseudocholinesterase (homozygous, heterozygous)
  • Dibucaine is a local anesthetic that inhibits pseudocholinesterase by 80% (Dib # = 80)
  • If pseudocholinesterase is atypical due to homozygous mutation, dibucaine will inhibit it by only 20% (Dib # =20)
  • If pseudocholinesterase is atypical due to heterozygous mutation, dibucaine will inhibit it by 40-60% (Dib # = 40-60)
  • Pts with homozygous mutation, Dib # 20, will have an extremely prolonged block with phase II characteristics. Heterozygous pts will have a moderately prolonged block.
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89
Q

Describe discovery of meperidine and why this is important in understanding its side-effects

A

First used for its anticholinergic activity, as it has a structure similar to atropine.

Side-effect is tachycardia.

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90
Q

Describe effects of bradykinin

A

Promotes vasodilation by increasing production of arachidonic acid metabolites and nitric oxide.

Increases natriuresis (sodium excretion) via direct tubular effects.

Usually degraded by ACE

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91
Q

Describe features of NMDA receptor activation

A

Cell membrane must be depolarized

Mg2+ removed by depolarization

Glutamate (+/- glycine) bind to ligand-gated channel

Sodium and CALCIUM influx (Ca2+ responsible for 2nd messenger signaling cascade)

Potassium efflux

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92
Q

Describe fluoride-induced nephrotoxicity

A

Related to hepatic metabolism of IA and production of fluoride ions causing direct toxicity to collecting ducts leading to high-output renal failure that is unresponsive to vasopressin.

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93
Q

Describe function of carotid body (ies)

A

Chemoreceptors that respond to reductions in arterial partial pressure of oxygen (PaO2), “hypoxic drive”.

Associated with afferent glossopharyngeal n. that are stimulated when PaO2 < 60-65mmHg, leading to increased MV.

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94
Q

Describe Henry’s Law.

Name a common application of Henry’s Law.

A

States that for a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.

Therefore, at equilibrium, there will be the same number of molecules existing in the gaseous phase and in the dissolved (liquid) phase, both exerting the same kinetic energy.

Common application = solubility of gases

  • As temperature drops, gas solubility increases
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95
Q

Describe Hepatic Artery Buffer Response system

A

Mediated by adenosine, used to maintain total hepatic blood flow when reciprocal changes occur in portal vein

ie: portal vein blood flow increases –> hepatic artery will vasoconstrict

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96
Q

Describe laminar flow

A

Particles flow in one direction, parallel to tube/wall and down a pressure gradient.

Flow is fastest in the center and decreases parabolically due to friction.

Resistance directly related to flow rate.

Poisseuille’s law follows laminar flow.

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97
Q

Describe landmarks for Femoral nerve block

A

Bony structures = ASIS (lateral), pubic tubercle (medial)

Inguinal ligament

Femoral vein –> Femoral artery –> Femoral nerve (medial –> lateral)

Femoral nerve lies superficial to psoas muscle, fascia iliaca draps its anterior

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98
Q

Describe MOA of antiplatelet activity of dipyridamole

A

Dipyridamole inhibits both PDE and adenosine reuptake. Normally, PDE breaks down cAMP. When cAMP levels are high, PLT unable to aggregate due to cAMP inhibition of thromboxane A2.

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99
Q

Describe origin and pathway of cardiac sympathetic fibers

A

Originate at T1-T4, traveling to the heart through cervical (stellate) ganglia.

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100
Q

Describe pharmacology of fenoldopam

A
  • Selective peripheral dopamine-1 receptor agonist
  • Causes systemic arteriolar vasodilation leading to reduced afterload
  • Improves renal blood flow, diuresis, natriuresis
  • Short duration of action and elimination half-time
  • Indicated for short-term management of HTN emergency
  • Side-effects include HA, flushing, reflex tachycardia, elevated IOP (related to arteriole dilation)
  • Contraindicated in pts with allergy to sulfa due to preservative, sodium metabisulfite
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101
Q

Describe production of CSF

A
  • Produced in the lateral ventricles by choroid plexus
  • 20 mL/h (500 mL/d)
  • Total CSF volume 100-150 mL, maintained via absorption at arachnoid villi in cerebral venous sinuses
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102
Q

Describe redistribution. Why is it an important concept?

A

[tissue]=[plasma] causes redistribution in which drugs return from tissues back into plasma, therefore, slowing the rate of decline in [plasma drug]. Redistribution generally delays emergence as tissue reservoirs continue to feed [plasma drug]

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103
Q

Describe relationship between volume of distribution and drug plasma concentration

A

Inverse relationship: Large VOD = lower [drug plasma]

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104
Q

Describe resonance of a system.

Name factors that increase the natural frequency of the system, and therefore minimizes resonance.

A

Every system has a frequency at which it oscillates, called the natural frequency. If a force with similar frequency to the natural frequency of a system is applied, the system will oscillate at maximum amplitude. This is resonance. Resonance produces excessive amplification that distorts the electrical signal. In an invasive arterial BP monitoring system, this results in greater SBP, lower DBP and increased pulse pressure.

Factors that minimize resonance:

  1. Reduce tubing length
  2. Reduce compliance of tubing
  3. Reduce density of fluid in tubing
  4. Increase diameter of tubing
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105
Q

Describe surfactants role in non-respiratory functions of the lung

A

Produced by type II alveolar epithelial cells, surfactant plays many roles outside of decrease surface tension within alveoli:

  • increases bacterial cell wall permeability
  • stimulates macrophage migration
  • stimulates synthesis of IgX and cytokines
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106
Q

Describe the basal ganglia:

  • site of input
  • site of output
  • associated dz state
A
  • Basal ganglia is part of the extrapyramidal system important for control of movement and posture
  • Basal ganglia are made up of the caudate nucleus, putamen, globus pallidus and substantia nigra
  • Site of input is via the striatum made up of the caudate nucleus and putamen
  • Site of output is via the globus pallidus and substantia nigra
  • Globus pallidus sends inhibitory outputs to the thalamus
  • Degeneration of the pars compacta substantia nigra alters basal ganglia neurotransmission causing Parkinson’s disease (dfxn dopaminergic pathway)
  • Degeneration of the caudate and putamen causes Huntington’s disease
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107
Q

Describe the Bezold-Jarisch cardiovascular reflex

A

Parasympathetic-mediated reflex occurs when stretch receptors located in the LV respond to an acute decrease in LV preload, resulting in bradycardia and reduced contractility.

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108
Q

Describe the corticospinal tract

A
  • Descending pathway involved in limb and axial motor movement

Precentral gyrus—> corona radiata and internal capsule—> pons—> 85% decussate to form pyramids and descend as the lateral corticospinal tract—> synapse in anterior/ventral horn onto lower motor neurons—> limb motor movement

…pons—>15% don’t decussate in brainstem but rather continue to descend ipsilaterally as the anterior corticospinal tract—> decussate at the anterior white commissure and synapse in anterior/ventral horn onto lower motor neurons—> axial motor movement

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109
Q

Describe the dorsal column/medial lemniscus pathway

A
  • Ascending pathway carries fibers that control fine touch and proprioception
  • 3 neuron system (DRG, cunate/gracile nucleus, VPL)

Peripheral receptors (Meissner’s and Pacinian corpuscles, muscle stretch receptors, golgi tendon organs)—> cell body located in DRG—> fibers travel up dorsal column (cunate or gracile fasciculus)—> terminate at cell body in medulla oblongata (nucleus of cunate or gracile)—> decussate to become the medial lemniscus—> synapse on the ventral posterior lateral (VPL) nucleus in thalamus—> travel through internal capsule—> terminate in postcentral gyrus

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110
Q

Describe the effect that disease states causing decrease in AcH receptors (ie: MG) has on NMB agents

A

Fewer AcH receptors demonstrates a sensitivity to depolarizing agents (sux, fewer receptors to depolarize) and increased sensitivity to non-depolarizing agents (fewer receptors to impose conformational change on)

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111
Q

Describe the Haldane effect

A

Describes CO2 transport from tissues to lungs

Based on fact that deoxyhgb has 3.5x more capacity for CO2 than oxyhgb

  • Once CO2 enters RBC (Hgb), it combines with H20 to form carbonic acid via carbonic anhydrase
  • Carbonic acid rapidly releases H+ protons, forming bicarbonate, which diffuses from the RBC into plasma; H+ protons bind to histidine residue of Hgb
  • Chloride ions replace bicarbonate to maintain neutrality
  • Once RBC reaches lungs, Hgb is met with high [O2], which decreases Hgb affinity for H+ ions
  • H+ then binds with bicarbonate to form CO2 + H20, CO2 is exhaled
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112
Q

Describe the lateral spinothalamic tract

A
  • Ascending pathway carries fibers involved in pain and temperature
  • 3 neuron system (DRG, substantia gelatinosa, VPL)

Peripheral receptors–> cell body in DRG—> ascend spinal cord through Lissauer’s fasciculus (white matter) 1-2 levels—> synapse onto cell body in dorsal horn = substantia gelatinosa (rex lamina II)—> axons decussate to the lateral spinothalamic tract—> synapse on the ventral posterior lateral (VPL) nucleus of the thalamus—> internal capsule—> postcentral gyrus

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113
Q

Describe the most important feature of CO2 absorbent. Why?

A

Granule size - Smaller granules have greater surface area for absorption but increased resistance to air flow.

Ideal granule size is 4-8 mesh

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114
Q

Describe the oculocardiac reflex (OCR)

A

Reflex that results in bradycardia, possible cardiac arrest secondary to traction on the EOM or pressure on the eyeball.

Stimuli at the eye –> ciliary ganglion –> ophthalmic division of trigeminal n –> gasserian ganglion –> trigeminal nucleus –> vagus n –> bradycardia

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115
Q

Describe the pattern of CNS symptoms in lidocaine toxicity

A

Perioral and tongue numbness > tinnitus > lightheadedness, dizziness > muscle twitching > seizures > coma > respiratory depression > cardiovascular collapse

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116
Q

Describe the Sciatic nerve, including origin and branches

A

Origin = L4-S3, lumbosacral nerve, travels down posterior thigh into popliteal fossa

Branches = Tibial nerve and Common Peroneal nerve

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117
Q

Describe therapeutic window

A

The range of a drug between the concentration associated with desired therapeutic effect and the concentration associated with a toxic drug response.

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118
Q

Describe Transient Neurologic Symptoms following spinal anesthesia.

Name risk factors.

A

Associated with lidocaine spinal anesthesia, causing LBP, buttocks and LE pain/sensory changes.

Risk factors include lidocaine anesthetic, lithotomy, ambulatory anesthesia.

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119
Q

Describe turbulent flow

A

Particles move in all directions, flow rate is the same across the diameter of the tube.

Pressure difference will increase to maintain flow and in turn increases resistance.

Gas density more important than viscosity.

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120
Q

Describes features of Fentanyl CSHT

A

Long and variable CSHT:

Highly lipophilic (hydrophobic) –> large VOD –> rapid redistribution–> requires metabolism by liver enzymes–> slower decrease in plasma drug concentration

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121
Q

Desflurane and impact on MAC delivered due to altitude changes

A

Desflurane Tec 6 vaporizer is a dual-gas blender that will deliver anesthetic directly proportional to the atmospheric pressure change.

In other words, MAC delivered will be inversely proportional to altitude change

(6% des (1 MAC) at 1 atm = 3% des (0.5 MAC) at 0.5 atm)

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122
Q

Desflurane has lower blood:gas coefficient number than N20 but slower rate of induction. Which concept explains this disparity?

A

Concentration effect of N20

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123
Q

Difference between carotid sinus vs. carotid body

A

Carotid sinus is a mechanoreceptor, responding to changes in pressure.

Carotid body is a chemoreceptor, responding to changes in oxygen/CO2 levels in blood.

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124
Q

Difference between physiologic dead space ventilation vs. physiologic shunt

A

Physiologic dead space ventilation applies to areas of the lung that are ventilated but poorly perfused, physiologic shunt occurs in lung that is perfused but poorly ventilated.

The physiologic shunt is that portion of the total cardiac output that returns to the left heart and systemic circulation without receiving oxygen in the lung.

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125
Q

Difference in vapor pressure between volatile anesthetics at 20 C

A

Desflurane 670 >>> Isoflurane 240 > Sevoflurane 160

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126
Q

Differential diagnosis: Hypoxemia and normal CXR

A

Pulmonary embolism

Obstructive lung dz (asthma)

Mucuos plugging

Intrapulmonary shunt

Methemoglobinemia

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127
Q

Downregulation of AcH receptors and NMBA

A

Downregulation causes decreased number of AcH receptors at NMJ due to sustained/chronic receptor agonism (chronic neostigmine use, organophosphate poisoning)

  • Decreased sensitivity/increased resistance to AcH/Suxx
  • Extreme sensitivity to NDNMBA
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128
Q

Drug used in post-op shivering

A

Meperidine

(Demerol)

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129
Q

Drug used to reverse central anticholinergic and also, hypnotic effects of ketamine

A

Physostigmine

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130
Q

Drugs that follow zero-order kinetics

A

THE PAW

Theophylline

Heparin

Ethanol

Phenytoin

Aspirin

Warfarin

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131
Q

Drugs that interfere with CSF production

A

Decrease CSF production:

  • acetazolamide
  • furosemide
  • thiopental

Increase CSF production:

  • desflurane
  • halothane
  • ketamine
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132
Q

E-cylinder gas and corresponding color (U.S.)

A

Oxygen: Green

Nitrous oxide: Blue

Carbon dioxide: Gray

Air: Yellow

Helium: Brown

Nitrogen: Black

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133
Q

ECG: Left anterior descending artery ischemia

A

Effects septal and/or anterior left ventricle

V1-V4, often V5-V6

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134
Q

ECG: Left circumflex artery ischemia

A

Effects lateral left ventricle.

I, aVL, V5-V6

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135
Q

ECG: Left main artery ischemia

A

Involves territory of LAD and LCx

I, aVL, V1-V6

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136
Q

ECG: Right coronary artery ischemia

A

Inferior territory

II, III, aVF

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137
Q

Effect of anti-epileptic drugs on neuromuscular blockade

A

Acute administration –> potentiates blockade

Chronic administration –> decreases duration of action of aminosteroid NDNMBA

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138
Q

Effect of co-administration of Ketamine and Mg2+. Why?

A

Potentiates effect of ketamine.

Mg2+ blocks NMDA receptor channel at rest, therefore, will assist in “antagonizing” the receptor.

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139
Q

Effect of damage to Recurrent Laryngeal nerve,

bilateral

A

Aphonia

Airway obstruction

*Partial injury to nerve = leads to bilateral adduction of vocal cords

Complete transection = paralyzed cords in paramedian position but act as “curtains” so still able to pass ETT

*partial nerve injury is worse

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140
Q

Effect of hypermagnesemia on NMBA blockade

A

Prolongs duration of action of NMBA blockade by inhibiting Ca2+ channels both pre and post-synaptically

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141
Q

Effect of hypokalemia on NDNMBA blockade and reversal

A

Hypokalemia potentiates blockade and decreases effectiveness of anticholinesterase antagonism of nondepolarizing blocks.

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142
Q

Effect of ionotropy

A

Positive ionotropes increase contractility, augment cardiac output and thereby enhance end-organ perfusion.

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143
Q

Effect on output and IA concentration if IA agents are placed into the wrong vaporizer

A

Vaporizers are IA agent specific based on differences in vapor pressure

  • if a vaporizer calibrated for high vapor pressure (ie: iso) is filled with an agent with low vapor pressure (ie: sevo), less output/lower agent concentration will be delivered
  • if a vaporizer calibrated for low vapor pressure (ie: sevo) is filled with an agent with high vapor pressure (ie: isoflurane), increased output/higher agent concentration will be delivered
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144
Q

Effects of Dobutamine

A

High affinity for beta-1 receptors, also acts on alpha-1 and beta-2 receptors but with equal affinity thereby resulting in no net effect on vascular tone

Increases conductance through the SA node

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145
Q

Effects of epinephrine on local anesthetic

A
  1. prolongs duration of block
  2. increases intensity of block
  3. decreases systemic absorption of LA

How? Epinephrine causes vasoconstriction that counteracts the vasodilatory effects inherent to LA. Therefore, epinephrine causes decreased systemic absorption, decreases intraneural clearance of LA and may have direct analgesic effects vvia alpha 2 receptors in brain and spinal cord.

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146
Q

Effects of nitric oxide (NO)

A

Also known as Endothelium-derived relaxing factor (EDRF)

Vasodilation

Antiaggregation of PLTs

Stimulates insulin release in pancreas

Modulates pain response

When bound to Hgb, causes pulm vasodilation

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147
Q

Effects of Phosphodiesterase inhibitors (PDIs) (Milrinone, amrinone, enoximone)

A

1) increase inotropy thereby improving cardiac output
2) improved lusitropy (myocardial relaxation)
3) decrease pulmonary vascular resistance thereby improve right ventricular outflow
4) vasodilation and reduced afterload

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148
Q

EKG finding for right ventricular hypertrophy

A

Large R wave in lead V1

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149
Q

Electrolyte abnormalities caused by thiazides

A

Hyponatremia

Hypokalemia

Hypomagnesia

Hypercalcemia

Hyperglycemia

Hypercholesterolemia

Hyperuricemia

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150
Q

Elimination of methohexital

A

Feces

All other barbiturates are renally excreted

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151
Q

Elimination of neostigmine

A

50% renal excretion, therefore, duration of action is likely to be prolonged in renal failure pts.

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152
Q

Endocrine effects of opioids

A

Suppresses FSH, LSH, ACTH, TSH, GH

Elevates prolactin

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153
Q

Enzyme inhibited by SSRIs?

A

CYP2D6

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154
Q

Equation for coronary perfusion pressure of left ventricle (CPPLV)

A

CPPLV = ADP - LVEDP

(Aortic diastolic pressure - LV end-diastolic pressure)

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155
Q

Equation: CO

A

CO= HR x SV

How to measure CO?

PA catheter

TEE

Esophageal doppler

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156
Q

Equation: Estimate time remaining in an E-cylinder

A

Time remaining (t)= Remaining cylinder pressure (PSi)/ (200 x Flow rate L/min)

(t) is measured in hours

Ex: 1000PSi remaining at Flow rate 5 L/min means you have 1 hr left to use that E-cylinder

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157
Q

Equation: MAP

A

MAP= SVR x CO

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158
Q

Equation: SVR

A

SVR= 80 x (MAP - CVP) / CO

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159
Q

Expected challenges in patients with Ankylosing Spondylitis (AS)

A

Difficult endotracheal intubation- AS as/w atlantoaxial instability and decreased ROM in cervical spine.

Difficult mask ventilation- TMJ hypomobility leads to ill-sealing facemasks.

AS as/w pulmonary fibrosis.

Epidural hematoma- lumbar spine fusion leads to increased attempts.

Many AS pts rely on NSAIDs for pain relief, resulting in plt dfxn and increased bleeding risk.

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160
Q

Explain difference between total body sodium and sodium concentration in vivo

A

Total body sodium caused by increase/decrease in ECV/plasma; involves aldosterone, ANP

Sodium concentration disorders due to excess/deficit of free water; involves ADH

*think: hyperaldosteronism as/w hypervolemia (increased ECV) resulting in HTN but is NOT as/w abnormal [Na+]

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161
Q

Facial nerve muscle innervation and TOF monitoring

A

Facial nerve innervates orbicularis oculi (moves eyelid) and corrugator supercili (moves eyebrow).

Neuromuscular blockade recovery time at the eyelid is similar to that of the adductor pollicis muscle (peripheral muscle), whereas recovery time at the eyebrow is similar to that of laryngeal muscles and diaphragm (central muscles).

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162
Q

Factors that affect the likelihood of terminating ventricular fibrillation via defibrillation (electrical current)

A

Low success:

  • time spent in dysrhythmia (longer time = worse outcome)
  • non-ischemic causes of cardiac arrest (tamponade, Tptx, PE, etc)

Higher success:

  • ischemic causes of cardiac arrest (MI)
  • applying firm pressure on paddles (~25 lbs)
  • using proper paddle size, conductive gel
  • defibrillating on end-expiration
  • stacked shock strengths
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163
Q

Factors that affect the rate of diffusion of gases across a membrane

A

Based on Fick’s Law of Diffusion

Vgas = A x D X (P1-P2) ÷ T

  • A = surface area of barrier
  • D = diffusion cofficient (directly proportional to solubility and inversely proportional to sq root of molecular wt)
  • P1-P2 = partial pressure difference across the barrier
  • T = barrier thickness

Factors that increase diffusion:

  • low molecular weight
  • increased solubility
  • increased partial pressure gradient
  • increased barrier surface area
  • decreased thickness of barrier
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164
Q

Factors that contribute to volume of distribution

A

Lipophilicity and protein binding

Lipophilic drugs and high tissue protein binding drugs have higher VoD

Increased plasma protein binding has smaller VoD

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165
Q

Factors that decrease MAC

A

IV anesthetics

Acute EtOH intoxication

Chronic amphetamine use

Lithium

Advanced age

Hyponatremia

Anemia

Hypercarbia

Hypoxemia

Hypothermia

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166
Q

Factors that determine resistance to gas flow in laminar flow

A

Gas viscosity and radius of the airway

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167
Q

Factors that determine resistance to gas flow in turbulent flow

A

Gas density and increasing flow rate

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168
Q

Factors that enhance alveolar concentration of inhaled anesthetic

A

Low blood solubility, decreased cardiac output, increased ventilation

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169
Q

Factors that increase insulin release

A

Enteral feeds

beta-adrenergic stimulation

alpha-adrenergic blockade

Nitric oxide

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170
Q

Factors that increase likelihood that flow in a tube will become turbulent

A
  • increased velocity
  • increased tube diameter
  • increased fluid density
  • decreased fluid viscosity

Reynolds number describes turbulent vs laminar flow

Reynolds number = (velocity x density x diameter) / viscosity

  • Reynolds number <2000 = laminar flow
  • Reynolds number >4000 = turbulent flow
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171
Q

Factors that increase MAC

A

Amphetamines

Cocaine

Ephedrine

Chronic EtOH use

Hypernatremia

Hyperthermia

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172
Q

Factors that increase risk of emergence rxn with ketamine

A

Adults > pediatrics

Womyn > men

Larger doses with rapid administration

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173
Q

Factors that increase risk of nausea with spinal anesthesia

A

Hx of motion sickness

Block above T5 (sympathectomy)

Hypotension

Opioid use

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174
Q

Factors that increase risk of post-op urinary retention

A
  • Pelvic/GU/rectal surgery
  • Hernia repairs
  • Periop urinary catheterization
  • Hx of urinary retention
  • Neuraxial anesthesia (increased risk with hydrophilic opioids, ie: morphine)
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175
Q

Factors that increase risk of pressure neuropraxia with LMA use

A

Overinflation of cuff

Prolonged operative times

Lidocaine lubrication

Difficult insertion

Use of nitrous oxide (displaces air within cuff and can increase cuff pressure by 30 mm Hg)

Cervical joint dz

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176
Q

Factors that potentiate (prolong) the action of NMBA

A
  • Volatile anesthetics
  • Local anesthetics
  • CCB
  • Beta blockers
  • Antibiotics (aminoglycosides)
  • Magnesium
  • Chronic steroid use
  • Dantrolene
  • Respiratory acidosis
  • Metabolic alkalosis
  • Hypothermia
  • Hypokalemia
  • Hypercalcemia
  • Hypermagnesemia
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177
Q

Factors that predict degree of nerve blockade by local anesthetic

A

Drug concentration and volume

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178
Q

Fasting guidelines

A

Clear liquids, 2H

Breast milk, 4H

Infant formula, 6H

Cows milk, 6H

Solids, 6H

Fried food, 8H

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179
Q

Features of stage 1, GA

A
  • induction stage, ends with LOC
  • respiration is slow but regular
  • eyelid reflex INTACT
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180
Q

Features of stage 2, GA

A
  • “excitement” phase- disinhibition, delirium, spastic movements
  • loss of eyelash reflex
  • divergent gaze
  • reflex pupillary dilatation
  • airway irritability- risk of cough, vomiting, laryngospasm, bronchospasm
  • irregular respirations and breath holding
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181
Q

Features of stage 3, GA

A
  • period when target level of surgical anesthesia is reached
  • cessation of eye movement
  • skeletal muscle relaxation
  • respiratory depression
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182
Q

Fentanyl and propofol are both highly lipophilic with large VOD. Why then does propofol have a shorter CSHT?

A

The rapid redistribution of fentanyl back to plasma prevents the plasma concentration from quickly falling after the infusion is stopped, even though fentanyl is rapidly cleared (1530 mL/min).

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183
Q

Fick equation for cardiac output

A

CO = O2 uptake by lungs (ml/min) / (O2 artery - O2 vein)

*arterial oxygen is from left heart, venous oxygen is from right heart

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184
Q

Fick equation: SvO2

A

SvO2 = SaO2 - [VO2 / (CO x Hgb x 1.36)]

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185
Q

Full E-cylinder: volume, pressure

A

Oxygen- 625 L, 2200 Psi

Air- 625 L, 2200 Psi

Nitrous- 1,590 L, 745 Psi

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186
Q

General causes of metabolic alkalosis

A

Vomiting (NG suctioning)

Diuretic use

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187
Q

GI side-effects of succinylcholine

A

Increased intra-gastric pressure and increased LES tone (LES tone effect > gastric pressure, therefore, as long as LES is competent, there is no increased risk of aspiration)

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188
Q

Graft Versus Host Disease (GVHD):

Pathology, S/Sx, Timing, Ppx

A

Pathology = Viable lymphocytes in DONOR blood attack recipient tissues. Recipient is IMMUNOSUPPRESSED so can’t mount response

S/Sx = fever, rash, cytopenia, liver dfxn, diarrhea

Timing = 3-4 wks post-transplant

Ppx = irradiated blood to reduce donor WBCs or leukoreduction filter use

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189
Q

Hepatic acinus zone most susceptible to toxins, ie: acetaminophen overdose

A

Zone 1, hepatocytes closest to hepatic arterioles and therefore, first zone to come in contact with blood toxins

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190
Q

Hering-Breuer reflex

A

Prevents overinflation of the lungs

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191
Q

How do changes in atmospheric pressure affect boiling point? Why?

A

Lower atmospheric pressure will lower boiling point. Boiling point is reached when vapor pressure of liquid is equal to the external pressure exerted on its surface. Therefore, if external pressure is lower, vapor pressure is lower.

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192
Q

How do changes in cardiac output effect uptake of volatile anesthetics in blood?

A

Higher CO > greater volume of blood perfuses the lungs > removes more inhalation anesthetic from alveoli > decreases concentration of anesthetic in lungs > lowers alveolar, arterial and therefore brain partial pressures of inhaled agent > delay in anesthetic induction

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193
Q

How does a right-to-left cardiac shunt effect IA induction? Why?

A

Slows induction.

First, anesthetic gas leaving pulmonary arteries are diluted by deoxygenated blood from the right heart.

Second, FA/FI is not effected much.

Even though there is a higher gradient between mixed venous partial pressure and alveolar partial pressure (favoring uptake), less lung is perfused to participate in gas exchange, so overall there is decreased uptake.

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194
Q

How does alkalinization speed onset of local anesthetics?

A

Alkalinization increases the percentage of molecules in their unionized form, therefore, molecules that can cross lipid bilayers and act on voltage-gated sodium channels

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195
Q

How does half-life of a drug relate to volume of distribution and drug clearance?

A

Half-life to clearance= inverse relationship, faster clearance= shorter half-life

Half-life to VOD= proportional relationship, larger VOD, longer half-life

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196
Q

How does HR influence hypotension?

A

Either tachycardia or bradycardia can cause hypotension if CO is decreased.

Bradycardia–> enhanced ventricular filling, increased SV but based on CO equation (CO= HR x SV), severely slow HR can lead to decreased CO

Tachycardia–> insufficient time for left ventricular filling resulting in low CO

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197
Q

How does plasma clearance effect context-sensitive half-time of a drug?

A

High plasma clearance = faster/shorter context-sensitive half-time (think Remifentanil)

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198
Q

How does PTH raise serum calcium levels?

A
  • stimulates osteoclastic bone resorption
  • activates distal tubule calcium reabsorption
  • conversion of vitamin D to calcitriol, which increases gut absorption of calcium
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199
Q

How does redistribution effect context-sensitive half-time of a drug? Why?

A

Slower redistribution = faster/shorter context-sensitive half-time

Drug is being cleared from plasma faster than drug returning to plasma from tissue compartments.

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200
Q

How does single administration epidural morphine compare to fentanyl?

A

Fentanyl is much more lipophilic than morphine, and will cross out of the epidural space resulting in a more restrictive segmental spread!

Since morphine is more hydrophilic, it does not cross out but rather remains within the epidural space with greater chance of rostral spread. This is why we worry about delayed respiratory depression with neuraxial morphine!

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201
Q

How long after the last dose of LMWH can neuraxial procedure be performed?

A

Therapeutic doses- 24 hrs

Prophylactic doses- 12 hrs

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202
Q

How much CO2 can soda lime absorb?

A

23-26L of CO2 per 100g of absorbent

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203
Q

How to calculate appropriate metabolic compensation for respiratory alkalosis

A

Acute = 24 - 0.2 x (40 - PaCO2)

Chronic = 24 - 0.5 x (40 - PaCO2)

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204
Q

How to calculate appropriate metabolic compensation for respiratory acidosis

A

Acute = 24 + 0.1 x (PaCO2 - 40)

Chronic = 24 + 0.4 x (PaCO2 - 40)

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205
Q

How to calculate appropriate respiratory compensation for metabolic derangement

A

Metabolic acidosis: Winter’s Formula

PaCO2 = (1.5 x HCO3-) + 8

Metabolic alkalosis: Summer’s Formula

PaCO2 = 40 + 0.6 x (HCO3- - 24)

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206
Q

Indication if CO2 absorbent cannister is too hot

A

Excessive CO2 production is occuring

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207
Q

Indications for arterial line

A

Surgery requiring deliberate HoTN, HTN- vascular, intracranial, trauma

Pts with severe valvular dz

CAD

CHF who can’t tolerate alterations in BP

Need to monitor ABG- pHTN, ARDS

Expected large volume shifts

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208
Q

Indications for perioperative non-invasive cardiac stress test

A

1) intermediate or high risk elective surgery
2) poor functional status (<4 METS) or unknown functional status
3) pt would agree to angiography if test were positive
4) care team agrees it would change pts overall care/outcome

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209
Q

Indications for prophylactic antibiotics to prevent infective endocarditis

A

Used in high-risk patients undergoing high-risk operations

High-risk factors:

  • prosthetic heart valves
  • prior hx of IE
  • unrepaired congenital cyanotic heart dz
  • repaired congenital heart dz (within first 6 mo of repair)
  • repaired congenital heart dz with residual defect
  • valvular dz in transplanted heart

High-risk operations:

  • dental work EXCEPT routine cleanings
  • respiratory tract biopsy
  • skin, MSK procedures
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210
Q

Inhalation anesthetic agent potentiation of neuromuscular blockade

A

Desflurane > sevoflurane > isoflurane > halothane > nitrous oxide

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211
Q

Inhaled anesthetic with highest vapor pressure

A

Nitrous oxide (3,800 mmHg)

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212
Q

Inspiratory effects on cardiac physiology

A

1) increased venous return –> increased RV preload
2) increased pulmonary venous capacitance –> decreased LV preload
3) increased intrathoracic pressure means LV has more pressure to overcome when contracting –> increased afterload
4) decreased LV preload + slight increase LV afterload –> slight decreased arterial BP
5) more RV preload delays pulmonic valve closure causing physiologic split of S2 (pulm and aortic valve closure)
6) increased HR due to inhibited vagal tone

213
Q

Intraop signs of Tension PTX

A

HoTN

Tachycardia

Decreased chest wall movement

Hyperresonance to percussion

Arterial hypoxemia

Decreased/absent breath sounds

Elevated inspiratory pressures

214
Q

Intraoperative signs and symptoms of anaphylaxis

A

Tachycardia

Refractory HoTN

Decreased pulmonary compliance

Arrhythmia

Urticaria

Periorbital/perioral edema

215
Q

Ions responsible for termination of neuronal action potentials

A
  1. voltage-gated sodium channels inactivated preventing further sodium influx
  2. voltage-gated potassium channels open and allow potassium efflux
216
Q

IV anesthetics that cause pain on injection

A

Propofol

Etomidate

Diazepam

Methohexital

Rocuronium

217
Q

IV dyes and effect on pulse oximetry

A
  • Methylene blue absorbs wavelengths at 668nm, close to red light absorption at 660nm seen with deoxyHgb. Therefore, methylene blue generates a higher R value leading to a FALSELY LOW SpO2.
  • Indigo carmine and indocyanine green also cause falsely reduced SpO2 readings but not to the same extent as MB.
218
Q

Lab abnormalities associated with chronic steroid use

A

Leukocytosis

Elevated hemoglobin

Hyperglycemia

Hypokalemia

Mild hypernatremia

Alkalosis

Increased urinary uric acid

Increased urinary calcium

219
Q

Lab test used to measure anticoagulant effect of unfractionated heparin, why?

A

aPTT

Unfractionated heparin enhances the affects of antithrombin 3, which inactivates multiple coagulation factors in the intrinsic pathway- thrombin (II) and factor Xa- which are measured by aPTT

220
Q

Laboratory findings in acute hemolytic transfusion rxn

A
  • +direct coombs test
  • elevated indirect and direct bilirubin
  • decreased haptoglobin
  • elevated LDH
  • elevated BUN
  • gross hematuria
  • elevated urinary urobilinogen
221
Q

Lambert-Eaton Syndrome and NMBA

A

SENSITIVE to BOTH NDNMBA and SUXX

222
Q

Levels of fluoride ion production between IA agents

A

Methoxyflurane >>> sevoflurane >> enflurane > isoflurane > desflurane

223
Q

Light wavelength absorption and pulse oximetry

A

Red light, emitted at 660nm, is absorbed by deoxyHgb

Infrared light, emitted at 940nm, is absorbed by oxyHgb

*this is why arterial blood appears more red than venous blood- oxyHgb absorbs IR light and scatters or reflects red light, making arterial blood appear more red!

224
Q

Main muscle of passive exhalation?

225
Q

Major c/o supraclavicular nerve block

226
Q

Major cause of hypothermia in pts undergoing general anesthesia?

A

Core-to-peripheral redistribution of body heat due to VA induced vasodilation and inhibition of tonic thermoregulatory vasoconstriction.

227
Q

Major differences between Polarographic (Clark electrode) and Galvanic oxygen analyzer

A
  • Clark electrode requires a battery source to polarize electrodes, allowing rxn to run faster than galvanic analysis
  • Exposing galvanic electrodes to air prolongs lifespan of analyzer (lower [oxygen] in air decreases consumption of electrodes by “slowing down” rxn)
228
Q

Major side-effect of mivacurium

A

Histamine release

229
Q

Maximum allowable dose of chloroprocaine?

230
Q

Mechanism of action: Phase II blockade

A

Continuous activation of AcH receptors leads to ongoing shifts in sodium influx/potassium efflux. However, increased activity of the Na-K ATPase pump moves the post-junctional membrane potential towards normal, resulting in a faded response to stimulation, a nondepolarizing blockade occurs.

231
Q

Mechanism of fail-safe system

A

Used to minimize the decrement in FiO2.

The system decreases the flow or halts gas administration (besides oxygen) when a decline in O2 pressure is sensed.

Prevents hypoxic mixture delivery.

232
Q

Mechanism of proportioning system

A

Prevents delivery of hypoxic fresh gas mixture if provider attempts to deliver disproportionate ratio of oxygen to nitrous, ie- 1 L/min O2: 4 L/min N2O, delivers <20% FiO2

233
Q

Medications that can cause HYPERkalemia

A

ACEi, ARBs

Potassium-sparing diuretics (spironolactone, amiloride)

Non-selective beta antagonist

NSAIDs

Sux

Heparin

Mannitol

Trimethoprim

234
Q

Metabolic byproducts of sodium nitroprusside responsible for toxicity

A

Cyanide and thiocyanate

235
Q

Metabolic compensation for acute vs. chronic Respiratory Alkalosis

A

Acute: [HCO3-] decreases 2 mEq/L per 10 mmHg decrease in PaCO2

Chronic: [HCO3-] decreases 5-6 mEq/L per 10 mmHg decrease in PaCO2

236
Q

Metabolism and elimination of Nicardipine. Contraindication?

A

Hepatic metabolism, eliminated via bile and feces.

c/i in hepatic disease states.

237
Q

Metoclopramide: MOA, uses, effects, contraindications

A

MOA= dopamine antagonist that works in the chemoreceptor trigger zone of CNS and also acts as a peripheral cholinergic agonist that enhances GI tissue response to AcH.

Uses= gastroparesis, N/V

Effects= accelerates gastric emptying, increases LES tone, decreases gastric fluid volume and relaxes pyloric sphincter

c/i= parkinson’s disease due to anti-dopaminergic effects

238
Q

MOA Adenosine

A

Inhibits influx of calcium through L-type channels and reduces the slope of uprise of phase 4 and reduces conduction through AV node.

239
Q

MOA Barbiturates

A

Depress the reticular activating system of the brainstem that controls consciousness, primarily through binding GABA a receptor.

240
Q

MOA causing sedation with dexmedetomidine

A

Alpha-2 agonism in locus ceruleous

241
Q

MOA Hydrochlorothiazide

A

Blocks Na+/Cl- co-transporter channels in distal convoluted tubules.

242
Q

MOA Neostigmine

A

Acetylcholinesterase inhibitor > increases amount of acetylcholine available at motor end plate

243
Q

MOA Vasopressin

A

Vasopressin= ADH= Arginine vasopressin (AVP)

AVP has two primary functions:

First, it increases the amount of solute-free water reabsorbed back into the circulation from the filtrate in the kidney tubules of the nephrons.

Second, AVP constricts arterioles, which increases peripheral vascular resistance and raises arterial blood pressure.

244
Q

MOA: Abciximab, Tirofiban, Eptifibate

A

Anti-PLT: Blocks glycoprotein IIa/IIIb receptors that bind fibrinogen

245
Q

MOA: Apixaban, Rivaroxaban

A

Direct factor Xa inhibition

246
Q

MOA: Aspirin

A

Anti-PLT: Inhibits thromboxane A2 synthesis

247
Q

MOA: Butorphanol.

What benefit does it have over other opioids?

A

mu agonist-antagonist with partial agonism at the kappa-opioid receptor.

Relieves biliary colic b/c it does not cause sphincter of Oddi contraction in the CBD leading to biliary spasm, like other opioids tend to do.

248
Q

MOA: Clopidogrel, Ticagrelor, Prasugrel

A

Anti-PLT: Inhibits ADP receptor activation on PLT membrane, inhibiting the expression of glycoprotein IIa/IIIb that binds fibrinogen

249
Q

MOA: Cyclophenolate

Effects caused by systemic absorption?

A

Anticholinergic drug used topically during ocular surgery to cause mydriasis.

Systemic absorption leads to CNS toxicity, ie: dysarthria, AMS, tachycardia, seizures

250
Q

MOA: Dabigatran

A

Direct thrombin inhibition

251
Q

MOA: Echothiophate

Effects caused by systemic absorption?

A

Anticholinesterase drug used to treat refractory glaucoma by causing miosis.

Systemic absorption leads to inhibition of plasma butyrylcholinesterase (pseudocholinesterase) and can cause prolonged duration of action with succ administration.

252
Q

MOA: Glucagon

A

Glucagon is synthesized and secreted by alpha cells of the pancreas –> activates G-coupled protein receptors –> stimulates adenylyl cyclase –> increased cAMP levels –> glycogenolysis, gluconeogenesis, inhibition of glycogen synthesis

*b/c glucagon increases cAMP, it also increases intracellular Ca2+ levels, leading to increased ionotropy and chronotropy and increasing MAP resembling epinephrine, NE

253
Q

MOA: Thiazides

A

Block Na/Cl co-transporter in the distal convoluted tubule causing decrease in Na (and water) reabsorption.

254
Q

MOA: UFH and LMWH

A

Bind serine protease inhibitor AT III causing a conformational change that increases its activity leading to inhibition of activated factor X and thrombin.

255
Q

Most common ambulatory surgery adverse events

A

1: Cardiovascular: HoTN, HTN, arrhythmia

Respiratory: hypoxemia, laryngospasm, bronchospasm

Pain

PONV

256
Q

Most common cause of emergence delirium?

A

Sevoflurane

257
Q

Most common cause of hemothorax

A

Bleeding intercostal vessels

258
Q

Most common cause of negative pressure pulmonary edema (NPPE)?

A

Laryngospasm

259
Q

Most common injury during MAC?

A

Respiratory depression due to over-sedation

260
Q

Most common side-effect of fospropofol

A

Paresthesias in perianal, genitals (incidence not decreased with use of LA, NSAIDS, etc)

261
Q

Most effective anti-emetic to prevent PONV in pediatric pts?

A

Ondansetron

262
Q

Most important accessory muscles of exhalation?

A

Abdominal muscles

263
Q

Most likely side-effect from succinylcholine?

Which pt population is most susceptible? Why?

A

Bradycardia.

Pediatric pts. have high vagal tone due to acetylcholine receptors at the SA junction.

Succinylcholine mimics action of Ach leading to bradycardia.

264
Q

Muscle responsible for vocal cord ABduction

A

Posterior cricoarytenoid (attached between posterior cricoid and arytenoid cartilage bilaterally)

265
Q

Muscles responsible for laryngospasm?

A

Lateral cricoarytenoid and transverse arytenoid muscle, both cause adduction of vocal cords

266
Q

Myasthenia Gravis and NMBA

A

SENSITIVE to NDNMBA

RESISTANT to SUXX

267
Q

Nail polish colors and effect on pulse oximetry

A

Blue, green, black and opaque acrylic nail polish lead to FALSELY LOW SpO2 readings.

268
Q

Name 2 byproducts of fospropofol metabolism

A

Formaldehyde, phosphate

269
Q

Name 2 factors that increase cilia activity

A
  • High-dose ketamine
  • Fentanyl
270
Q

Name 2 of the greatest risk factors for bradycardia with succinylcholine use

A
  • repeat dosing (especially within 5 minutes)*
  • young age

*succinylcholine metabolic products- succinylmonocholine and choline- sensitive the myocardium to parasympathetic effects of a second dose of succinylcholine

271
Q

Name 4 potassium-sparing diuretics

A

Spironolactone

Amiloride

Triamterene

Eplerenone

272
Q

Name 5 causes of low preload

A

1) Hypovolemia (hemorrhage, fluid losses, NPO status)
2) Venodilation (GA, neuraxial anesthesia)
3) PTX (prevent ventricular filling due to increased pressure around the heart)
4) Pericardial tamponade (same mechanism as PTX)
5) Pulmonary embolism (effects right heart ability to pump sufficient blood to left heart for CO)

273
Q

Name 5 factors that effect cardiac output

A
  • Preload
  • Afterload
  • Myocardial contractility
  • HR
  • Rhythm
274
Q

Name 7 NMDA receptor antagonist

A

Ketamine

Methadone

Tramadol

Nitrous oxide

Dextromethorphan

Memantine

Magnesium

275
Q

Name byproduct of thiopental metabolism (during infusion) and effects

A

Thiopental infusion –> desulfurization –> Pentobarbital

CNS depression.

276
Q

Name causes of LEFT and RIGHT shift in the oxyhemoglobin dissociation curve

A

Left shift: increased Hgb affinity for O2, less unloading

  • decrease pCO2
  • decrease [H+] = increase pH
  • decrease 2,3-DPG
  • hypothermia
  • HbF

Right shift: decreased Hgb affinity for O2, more unloading

  • increase pCO2
  • increase [H+] = decrease pH
  • increase 2,3-DPG
  • hyperthermia
277
Q

Name causes of nicotinic AcH receptor upregulation

A

Stroke

Spinal cord injury

Burns

Prolonged immobilization

Prolonged exposure to NMBA

Myopathies (Duchennes MD)

Denervation d/o (MS, GBS, ALS)

278
Q

Name drugs known to decrease pseudocholinesterase activity (therefore, prolong the duration of action of depolarizing NMBA sux)

A

Echothiophate (glaucoma drug)

Neostigmine, pyridostigmine

Phenelzine (MAOI)

Cyclophosphamide

Metoclopramide

Esmolol

OCP

279
Q

Name drugs whose termination of action is primarily due to redistribution (following single bolus dose). Why?

A

Thiopental, propofol, fentanyl, methohexital.

Lipophilicity

280
Q

Name factors that decrease cilia activity

A
  • smoking
  • dry gas inspiration
  • extreme temperature exposure
  • dehydration
  • inhaled anesthetics
  • opioids
  • atropine
  • alcohol
281
Q

Name factors that decrease MAC

A

Older age

Acute alcohol intoxication

Anemia

PaCO2 >95mmHg

Hypotension (MAP <40mmHg)

Hyponatremia

Hypercalcemia

Pregnancy

282
Q

Name factors that increase MAC

A

Young age

Chronic alcohol use

Hypernatremia

Cocaine

Ephedrine

T >42C (hyperthermia)

MAOI, Levodopa use

283
Q

Name factors that speed induction (and elimination) of inhaled anesthetics

A

Elimination of rebreathing

High fresh gas flows

Low anesthetic-circuit volume

Low absorption by anesthesia circuit

Decreased solubility of IA

High CBF

Increased ventilation

284
Q

Name subcortical areas of the forebrain and associated functions

A
  1. Thalamus:
  • made up of nuclei, acts as a relay station for motor, sensory, limbic, auditory and visual systems
  • involved with arousal
  1. Hypothalamus:
  • controls ANS
  • endocrine fxn via pituitary
  • thermoregulation
  • circadian rhythm
  1. Epithalamus:
    * pineal gland (produces melatonin)
  2. Basal ganglia:
    * movement
  3. Hippocampus:
    * memory and learning
  4. Amygdala:
  • “fight-or-flight” response
  • fear, emotions
285
Q

Name the afferent limb of laryngospasm reflex

A

Internal branch of superior laryngeal nerve

286
Q

Name the blood components in cryoprecipitate

A

Factor VIII and XIII

FIBRINOGEN

Von Willebrand Factor

Fibronectin

287
Q

Name the coagulation factor not found in cryoprecipitate

A

Factor VII

288
Q

Name the criteria required for TRALI diagnosis

A
  • acute onset hypoxemia within 6 hrs of tranfusion
  • bilateral pulmonary infiltrates on CXR
  • NO cardiogenic cause of pulmonary edema (therefore, PCWP < 18 mmHg)
  • NO pre-existing lung injury
289
Q

Name the metabolite of morphine and meperidine

A

Morphine = morphine-6-glucoronide

Meperidine = normeperidine

*both are active metabolites that require renal elimination, therefore, dose adjustment in pts with renal failure

290
Q

Name the specific benzodiazepine-receptor antagonist

A

Flumazenil

291
Q

Name the vessel-poor tissue groups that receive lowest proportion of cardiac output

A

Bone, ligament, cartilage

292
Q

Name the vessel-rich tissue groups that receive highest proportion of cardiac output.

Why is this important?

A

Brain, heart, lungs, liver, kidney, endocrine glands

These tissues approach equilibration with the [plasma] more rapidly due to blood flow

293
Q

Name three factors that affect inhaled anesthetic uptake

A

Blood solubility

Alveolar blood flow (cardiac output)

Difference in partial pressure between alveolar gas and venous blood

294
Q

Name two scenarios where atropine is ineffective in treatment of bradycardia

A

1) Complete heart block (atropine works on SA node)
2) Transplanted heart (lacks innervation)

295
Q

Name ways to decrease resistance (therefore, turbulent air flow) in a breathing system

A

Increase diameter of circuit tubing

Minimize sharp bends

Decrease circuit length

296
Q

Nerve injury resulting in winged scapula

A

Long thoracic (C5-6-7) and dorsal scapular (C5) nerves

297
Q

Nerves blocked by Femoral nerve block

A

Anterior cutaneous nerves (anterior thigh)

Infrapatellar branch of Saphenous nerve (below knee cap)

Saphenous nerve - medial lower extremity

298
Q

Neuraxial anesthesia: Cardiovascular effects

A

Veno-arterial vasodilation (venodilation >> arteriodilation) with decreased preload and SV

T1-T4, cardiac sympathetic fibers, bradycardia

Biphasic CO: initially, increased SVR with increased CO; eventually, increased venodilation with decreased preload and CO

299
Q

Neuraxial anesthesia: Layers encountered with midline approach

A

Supraspinous ligament > interspinous ligament > ligamentum flavum > epidural space (LOR) > dura mater “pop” > subarachnoid space with cauda equina and CSF

300
Q

Neuraxial anesthesia: Order of nerve fiber sensitivity

A

Most sensitive, blocked first= preganglionic sympathetic fibers

Sensory, C fibers= temp. (cold)

Sensory, A delta= pinprick, sharp

Sensory, A beta= touch

Least sensitive, blocked last= Motor A alpha

301
Q

Null Hypothesis (Ho)

A

States there is NO difference between the variables tested

302
Q

Odds ratio interpretation

A

Measure of association between exposure and an outcome.

The OR represents the odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure.

303
Q

Opioids associated with Serotonin syndrome; why?

A

Some opioids have 5-HT1A agonism that augments serotonin release and weakly inhibits reuptake, therefore, increasing synaptic serotonin levels

  • fentanyl
  • tramadol
  • methadone
  • meperidine
304
Q

Order of non-depolarizing NMBA potentiation by IA

A

Desflurane > Sevoflurane > Isoflurane > Halothane

305
Q

PaO2 : FiO2 ratio in TRALI

A

200 - 300 mmHg

306
Q

Pathophysiology of negative pressure pulmonary edema (NPPE)

A

Acute glottic closure (laryngospasm)–> pt continues to inspire against closed glottis –> generates sudden increase in negative intrathoracic pressure –> increased venous return to right heart and pulmonary arteries –> increased volume expansion causes high arteriole/capillary fluid pressure that favors transudation into alveolar space

307
Q

Pathway involved in transmission of pain?

A

Lateral spinothalamic tract

*also responsible for temp and touch

308
Q

Rate of systemic absorption of local anesthestics by site

A

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

309
Q

Peripheral action of opioids on spinal cord

A

Acts to suppress Substance P in dorsal horn, substantia gelatinosa

310
Q

Polymorphism and effect: MCIR gene

A

Increased analgesia

Red hair

311
Q

Polymorphism and effect: OPRM gene

A

Decreased efficacy of morphine

312
Q

Possible side effect of antidopaminergic medications, ie: metoclopramide, droperidol, prochlorperazine. Treatment?

A

Extrapyramidal symptoms (EPS)- acute dystonia, akathisia, tardive dyskinesia

Tx = anticholinergic medication, ie: diphenhydramine, benztropine, atropine

313
Q

Post-MI medications that reduce complications and risk factors for repeat MI

A

Beta-blocker

ACE inhibitor

HI statin

ASA

*if EF <35%, add spironolactone

314
Q

Potential side effect of chronic dantrolene use (tx of muscle spasticity 2/2 cerebral palsy, MS)

A

Liver failure (requires routine LFT monitoring)

315
Q

Predict difficulty with LMA placement

A

R(R)ODS

Restricted mouth opening

Resistance of airway (restrictive airway dz)

Obstruction

Distorted anatomy

Short TM distance

316
Q

Preop criteria for delivery of MAC

A

Pt must be able to remain motionless and, if necessary, actively cooperate throughout the procedure

*exclusion = cognitive dfxn, CHRONIC COUGHING, Tourettes

317
Q

Pressure units:

cmH20 : mmHg

A

10 cmH20 : 7.4 mmHg

318
Q

Primary adrenergic receptors and location

A

beta-1: exclusively in cardiac muscle, ionotropy, chronotropy

beta-2: vascular smooth muscle, vasodilation

alpha-1: vascular smooth muscle, vasoconstriction

dopamine 1 and 2: renal, splanchnic vasculature, vasodilation

319
Q

Primary determinant of myocardial oxygen consumption?

A

HR (ventricular contraction rate per minute)

320
Q

Primary determinant of oxygen reserve when apnea occurs

321
Q

Primary factors affecting spinal block height

A

LA dose

LA baricity

Pt positioning

322
Q

Primary indications for electrical defibrillation

A
  • ventricular fibrillation
  • pulseless ventricular tachycardia
323
Q

Principle for which strain gauges work

Where are strain gauges found?

Why?

A
  • The principle that the electrical resistance of a wire increases as it extends.
  • Strain gauges are incorporated into pressure transducers used for invasive arterial BP monitoring. The constant variation of BP through an arterial catheter is connected to a column of saline, which transmits pulse pressure through this pressurized column onto a flexible diaphragm, causing the shape of the diaphragm to change. The displacement of the diaphragm is measured by a strain gauge.
  • Used to convert mechanical energy (pulsatile BP) into electrical energy.
324
Q

Proper head positioning for intubation

A

Sniffing position= neck flexed 35 degrees with head extended 15 degrees brings oral-pharyngeal axis to 125 degrees (with displacement of the tongue during DL, provides 180 degrees and view of glottis)

325
Q

Propofol and egg allergy

A

Propofol is not contraindicated in pts with egg allergy, why?

Egg lecithin used in propofol emulsion is derived from egg yolk. Most egg allergies are due to egg albumin found in egg whites.

326
Q

Propofol causes decrease in ICP but not increased CPP, why?

A
  • Remember: CPP = MAP - ICP
  • Propofol causes both venodilation and arterodilation leading to decreased MAP > ICP. Ultimately, propofol results in reduced CPP.
327
Q

Purpose of the check valve

A
  • located between the vaporizers and common gas outlet
  • permit only unidirectional flow of gases
  • prevent retrograde flow of gases from the anesthesia machine or the transfer of gas from a compressed-gas cylinder at high pressure into a container at a lower pressure
328
Q

Purpose of the fail-safe valve

A

Discontinue the flow of N2O (or proportionally reduce it) if the O2 pressure within the anesthesia machine falls below 30 psi

329
Q

Respiratory compensation for metabolic acidosis

A

PaCO2 decreases 1.2 mmHg per 1 mEq/L of [HCO3-] to minimum of 10-15 mmHg

330
Q

Respiratory compensation for metabolic alkalosis

A
  • PaCO2 increases 0.5 mmHg per 1 mEq/L increase in [HCO3-]
  • Last 2 digits of pH should approximate [HCO3-] + 15
331
Q

Respiratory effects due to laparoscopic surgery

A

Decreased lung compliance

Increased V/Q mismatch

Increased inspiratory pressure

Increased PaCO2 and decreased blood pH

332
Q

Respiratory effects of propofol

A
  • profound respiratory depression leading to apnea
  • blunts medullary respiratory center response to PaCO2 (therefore, need a higher PaCO2 before spontaneous ventilation will resume)
  • decreases TV
  • bronchodilation
  • minimal effect on hypoxic pulmonary vasoconstriction
333
Q

Reynolds number equation

Significance?

A

Reynolds number = (velocity x density x diameter ) / viscosity

RN < 2000 = laminar flow

RN > 4000 = turbulent flow

334
Q

Risk factor for anaphylac-tic/toid transfusion rxn

A

IgA deficiency

335
Q

Risk factors for CAD

A

Smoking

DM

Age

High LDL

Low HDL

336
Q

Risk factors for CNS toxicity due to local anesthetic

A

#1= LA POTENCY (lipophilicity)

  1. decrease in protein binding
  2. systemic acidosis
  3. hypercapnia
  4. hypercarbia
337
Q

Risk factors for endobronchial intubation

A

Neck hyperflexion

Elevated diaphragm, ie: pneumoperitoneum

Head down position “ETT tip follows the chin”

338
Q

Risk factors for laryngospasm

A

Light plane of anesthesia

Extubation during phase II

Oropharyngeal secretions

Recent URI

Pediatric pts

Hx of reactive airway dz

Second-hand smoke exposure

339
Q

Risk factors for perioperative aspiration

A

Emergency surgery

Trauma

Bowel obstruction

Morbid obesity

AMS

Age >60 yo

Pregnancy

DM

Severe GERD

340
Q

Risk factors for post-op cognitive dysfunction (POCD)

A

Advanced age

Lower educational level

Hx of CVA

341
Q

Risk factors for post-op nausea/vomiting (PONV)

A

Womyn

Hx of PONV and/or motion sickness

Non-smokers

Age <50

GETA IA, esp nitrous oxide

Post-op opioids

Surgical type- laparoscopy, gyn, breast, eye surgery

342
Q

Risk factors for relapse in Anesthesiologist returning to clinical duties

A

FHx of substance use

Use of major opioid, ie: fentanyl

Presence of co-existing psychiatric d/o

343
Q

Risk factors of normeperidine-induced seizures

A
  • chronic meperidine therapy
  • large doses meperidine over short period of time
  • renal failure
344
Q

Risk of barbiturate administration in patients with this genetic disorder

A

Acute Porphyria Crisis, presenting with severe abdominal pain, nausea and discolored urine.

345
Q

Risks associated with mannitol administration

A

Hypovolemia leading to systemic HoTN

Acute mannitol toxicity

  • hyponatremia
  • elevated serum osmolality

Exacerbation of edema

346
Q

Risks associated with perioperative hypothermia

A

Post-op myocardial ischemia

Poor wound healing and infection

347
Q

Safeguards to ensure proper delivery of gas during ventilation

A

DISS, PISS Flowmeter sequence (oxygen outlet located in downstream position)

Fail-safe system

Proportioning system

Oxygen analyzer (last safety mechanism in line before gas delivered to patient; measures oxygen concentration beyond fresh gas outlet)

348
Q

Secondary uses of glucagon. Why?

A

Treatment of beta-blocker overdose

Treatment of anaphylaxis in pts taking beta blockers

Glucagon acts on G-coupled protein receptors and increases cAMP levels and Ca2+ levels by bypassing the second messenger system providing ionotropy and chronotropy and increasing MAP.

349
Q

Sensitivity

A

TP/ TP + FN

“Rules Out” disease

Screening test should be highly sensitive

350
Q

Sensory innervation of medial leg

A

Saphenous nerve, a branch of the femoral n.

351
Q

Side effect from damage to the preoptic nuclei of anterior hypothalamus

A

Impaired thermoregulation

352
Q

Side effects: Dexmedetomidine

A

Bradycardia

HoTN

Dry mouth

Nausea

353
Q

Side-effect of digoxin

A

Yellow-green color vision d/o

354
Q

Side-effect of furosemide

A

Hypokalemic- hypochloremic metabolic alkalosis

355
Q

Side-effects of amiodarone

A

Class III antiarrhythmic that blocks potassium channels

  • Bradycardia, HoTN (risk factors include age >60 yo and higher dose therapy)
  • AV nodal block
  • Prolonged QT interval, torsades de pointes
  • Acute pulmonary toxicity (risk remains present for duration of amiodarone t1/2 of 45 days)
  • Hypothyroidism
  • Hyperthyroidism storm resulting in high output CHF
  • Skin hyperpigmentation causing blue-grey appearance
  • Optic neuritis and corneal deposits
  • Statin-induced myalgias
  • Elevated LFTs
356
Q

Side-effects of neostigmine

A

Activation of parasympathetic NS:

  • bradycardia
  • hypotension
  • bronchospasm
  • increased secretions
  • miosis
  • decreased IOP
357
Q

Side-effects of sodium bicarbonate administration

A

Hypocalcemia

Hypokalemia

HoTN

358
Q

Side-effects of spironolactone

A

Hyperkalemia

Hyponatremia

Gynecomastia

Impotence

359
Q

Side-effects of sugammadex

A

1: anaphylaxis/hypersensitivity rxn

Increased risk of unintentional pregnancy if on OCPs

Prolonged PT/INR and aPTT

Arrhythmias

HoTN

360
Q

Side-effects of thiazide diuretics

A

1) increased excretion chloride > hypochloremic metabolic alkalosis
2) increased excretion sodium > hyponatremia
3) increased excretion potassium > hypokalemia
4) directly inhibit calcium excretion > hypercalcemia

361
Q

Sign of bladder perforation during TURP

A

Abdominal pain, shoulder pain, nausea

362
Q

Sign of NGT placement into trachea?

A

Collapse of reservoir bag after NGT placed to suction

363
Q

Significance of increased A-a gradient in presence of hypoxemia?

A

Hypoxemia is then secondary to:

  • V/Q mismatch
  • pulmonary shunt (perfused lung that receives no ventilation)
  • diffusion barrier/restriction
364
Q

Significance of normal A-a gradient in presence of hypoxemia?

A

Hypoxemia is then secondary to either hypoventilation or decreased inspired oxygen concentration.

365
Q

Signs and symptoms of acute hemolytic transfusion rxn

A

Tachycardia

HoTN

Bronchospasm

Hives

Hemoglobinuria

366
Q

Signs and symptoms of Brown-Sequard syndrome

A

Partial spinal cord transection resulting in:

  • ipsilateral motor deficit below injury (weakness, due to transection of corticospinal tract)
  • ipsilateral loss of vibratory and joint positioning (due to transection of dorsal column)
  • contralateral loss of pain and temp 1-2 levels below lesion (due to transection of spinothalamic tract)
367
Q

Signs and symptoms of fluoride-induced nephrotoxicity

A

Hypovolemia

Polyuria

Elevated BUN, Cr

Hypernatremia

Serum hyperosmolality

368
Q

Signs and symptoms of hemolytic transfusion rxn due to ABO mismatch

A

Fever, chills

Nausea, vomiting

Diarrhea

Chest and back pain

Acute renal failure

DIC

369
Q

Signs and symptoms of lower motor neuron injury

A

Injury to peripheral neuron after its synapsed in the anterior horn, resulting in:

  • flaccid paralysis
  • diminished or absent DTR
  • muscle atrophy
  • +/- fasciculations
370
Q

Signs and symptoms of serotonin syndrome

A

Agitation, tremor

Tachycardia, HTN

Diarrhea

Mydriasis

Hyperthermia

Symmetric hyperreflexia

Myoclonus, rigidity

Autonomic instability

DIC, rhabdomyolysis

Seizure, coma

371
Q

Signs and symptoms of tension pneumothorax

A
  • Cyanosis
  • Tachypnea
  • HoTN
  • *Distended neck veins
  • tracheal deviation
  • absent breath sounds on affected side

*JVD may be absent in hypovolemic pts

372
Q

Signs and symptoms of upper motor neuron injury

A

Injury to cerebral cortex or descending pathway in spinal cord resulting in:

  • spastic paralysis
  • hyperactive DTR (ie: + babinski)
373
Q

Signs and symptoms that distinguish TACO from TRALI

A

Signs of volume overload are specific to TACO:

  • increased JVD
  • peripheral edema
  • HTN
374
Q

Signs of anticholinergic toxicity

A

Delirium/AMS

Decreased secretions- dry mucous membranes

Mydriasis

Hyperthermia

Decreased GI/GU activity

375
Q

Signs of cardiac tamponade

A

Becks triad:

HoTN

Distended neck veins

Muffled heart sounds

Narrow pulse pressures

376
Q

Signs of cranial base skull fracture

A

Battle sign (mastoid ecchymosis)

Raccoon eyes

Bleeding from ears or nose

377
Q

Signs of endobronchial intubation

A

Decrease oxygen saturation

Increase in peak airway pressure

Increase in plateau airway pressure

378
Q

Signs of incomplete vs complete spinal cord injury

A

Incomplete injury s/f sacral sparing:

  • voluntary contraction of the anus
  • sensory preservation over sacral distribtution
379
Q

Signs of spinal cord injury in comatose patients

A
  • Flaccid areflexia
  • Loss of rectal sphincter tone
  • Paradoxic respiration
  • Bradycardia in hypovolemic pt
380
Q

Signs/symptoms Central Anticholinergic Syndrome

A
  • Cutaneous vasodilation
  • Anhidrosis
  • Hyperthermia
  • Mydriasis
  • AMS
  • Urinary retention
  • +/- respiratory depression

“Red as a beet, Dry as a bone, Hot as a hare, Blind as a bat, Mad as a hatter, Full as a flask”

381
Q

Signs/symptoms of ASA syndrome

A

Anterior spinal artery syndrome, due to interruption of blood flow to anterior spinal artery:

Bilateral LE paraplegia

Bowel/bladder dfxn

Loss of pain and temp

Proprioception and vibration are preserved as posterior portion of spinal cord is supplied by PSA.

382
Q

Specific vs Non-specific beta blockers

A

Specific:

  • act on beta 1 receptors in cardiac myocardium and on SA node
  • slow SA node conduction
    • metoprolol
    • atenolol

Non-specific:

  • act on beta 1 and beta 2 receptors
  • beta 2 receptors found on vascular smooth muscle and bronchioles
  • slows SA node conduction
  • decreases SVR
    • labetalol
    • propranolol
    • carvedilol
383
Q

Specificity

A

TN/ TN + FP

“Rules In” disease

Confirmatory test should be highly specific

384
Q

Steps to resolve laryngospasm

A

Apply pressure to retromandibular notch

Apply 15-20 cm CPAP, 100% oxygen

Administer 1mg/kg propofol

Administer 0.5mg/kg sux (add 0.01mg/kg atropine in peds due to risk of severe bradycardia with sux)

385
Q

Structures visualized in Laryngoscopic Grade II view of airway

A

Partial glottis:

Epiglottis

Posterior features of true vocal cords

Arytenoids

386
Q

Structures visualized in Laryngoscopic Grade III view of airway

A

Epiglottis only

387
Q

Structures visualized in Laryngoscopic Grade IV view of airway

A

Glottis structures are not visualized

388
Q

Structures visualized in Mallampati II

A

Hard palate

Soft palate

Uvula

389
Q

Structures visualized in Mallampati III

A

Hard palate

Soft palate

390
Q

Structures visualized in Mallampati IV

A

Hard palate only

391
Q

Suspected anaphylaxis: what lab is helpful in this diagnosis?

Why?

A

Tryptase levels, drawn within 1-2 hrs of rxn.

Tryptase is released from mast cells when activated by IgE, the immune cells involved in type I hypersensitivity rxn, anaphylaxis.

392
Q

Symptom of hypoglycemia seen in pts taking beta blockers

A

Diaphoresis

Sweat glands are innervated by sympathetic nervous system using acetylcholine neurotransmitter onto muscarinic receptors, therefore, beta blockade will not prevent sweating due to hypoglycemia

393
Q

Symptoms of epidural abscess?

Most common pathogen?

A

Fever, back pain and progressive neurological symptoms.

Staph Aureus from skin flora.

394
Q

Systemic effects of IV Mg2+. Why?

A

General: Flushing, N/V

Neuro: Sedation, dizziness, muscle weakness, loss of DTR

Cardiac: HoTN, bradycardia, PR prolongation, widened QRS, complete heart block

Increased sensitivity to NDNMBA, therefore, use smaller doses in pts with hypermagnesemia

IV Mg2+ is a calcium channel antagonist that affects the presynaptic Ca channels and decreases release of AcH while also decreasing the motor end plates sensitivity to AcH.

395
Q

TEG interpretation

A

R time= time to start clot formation; problem with coag factors; tx = FFP

K time= time until clot reaches full strength; problem with fibrinogen; tx= cryoprecipitate

alpha angle= speed of fibrin accumulation; problem with fibrinogen; tx= cryoprecipitate

MA= problem with platelets; tx= PLT and/or DDAVP

LY30= lysis of clot at 30 minutes; problem with excess fibrinolysis; tx = TXA and/or aminocaproic acid

396
Q

Temporal effects of smoking cessation

A
  • <24 hrs: right shift of oxygen dissociation curve
  • 48-72 hrs: increased secretions and reactive airways
  • 2-4 weeks: decreased secretions and reactive airways
  • 4-6 weeks: normalized immune system and metabolism
  • 8-12 weeks: improved mucociliary transport and small airway function
397
Q

Termination of dural sac and conus medullaris: Adults vs. Infants

A

Adults- dural sac, S1; CM, L1

Infants- dural sac, S3, CM, L3

398
Q

The rate at which alveolar concentration of anesthetic agent rises to meet the inspired concentration (rate of rise of FA/FI) is primarily determined by which pair of factors?

A

MV and inspired concentration

Other important factors that determine uptake in blood of agent are:

  • solubility
  • CO
  • difference between partial pressure of anesthetic agent in alveolus vs mixed venous blood
399
Q

Three risk factors that determine death rate from major burns?

A
  1. Inhalation injury
  2. Burn size >40% TBSA
  3. Age > 60 yo.
400
Q

TRALI: Pathophysiology, Tx

A

Underlying etiology not definitely known; 2 hypothesis:

  • donor blood contains anti-HLA or HNA antibodies that activate complement cascade, resulting in neutrophil recruitment to pulmonary vasculature resulting in endothelial damage and capillary leakage leading to pulmonary edema
  • Two-hit model: stress (surgery, trauma, infxn) causes neutrophil sequestration in the lungs; transfusion contains donor antibodies against HLA or HNA substypes resulting in neutrophil activation and lung injury

Tx:

  • supportive- supplemental oxygen, PPV, IVF, vasopressors
  • steroids (to reduce inflammatory response)
  • DIURESIS NOT INDICATED AND MAY CAUSE FURTHER DAMAGE!!!!
401
Q

Tranfusion Rxn, Febrile Non-hemolytic Transfusion Rxn:

Pathology, S/Sx, Timing, Risk factors, Tx

A

Pathology = antibodies in the DONOR blood react with the recipient’s WBCs, activating the inflammatory cascade, causing fever and chills.

S/Sx = Temp increase 1-2 ºC, chills, rigors, anxiety, and headache

Timing = within 4 hrs of initiating transfx

Risk factor = hx of chronic transfusions; why? antibodies increase with a greater number of tranfusion exposures

Ppx tx = NSAIDS, acetaminophen

Tx = STOP transfusion

402
Q

Transfusion Rxn, Acute Hemolytic Transfusion Rxn:

Pathology, S/Sx, Timing, Tx

A

Pathology = ABO incompatibility due to IgM ab-antigen complexes activating complement system resulting in intravascular and extravascular RBC hemolysis

S/Sx = The release of bradykinin causes fever, hypotension, and hemodynamic instability, while histamine release from mast cells leads to bronchospasm and urticaria, as well as symptoms of dyspnea, flushing, and severe anxiety; hemoglobinuria, DIC

Timing = immediate

Tx = STOP TRANSFUSION, resuscitation

403
Q

Transfusion Rxn, Delayed Hemolytic Trans Rxn (DHTR):

Pathology, S/Sx, Timing, Tx

A

Pathology = RECIPIENT blood contains minor antigens (Rh, Kell, Kidd, Duffy) from prior transfusion, pregnancy that react to DONOR RBC antibodies

S/Sx = mild fever, +/- rash, jaundice (^ direct bili), hemoglobinuria, +/- anemia, + direct coomb’s test

Timing = 3-10 days post-transfusion

Tx = supportive

*note: sx >mild than AHTR b/c hemolysis of RBC occur extravascular in reticuloendothelial system - spleen and liver

404
Q

Treatment for nausea associated with spinal anesthesia. Why?

A

Anticholinergic drugs (atropine, glycopyrollate)

Sympathectomy due to spinal anesthesia leads to unopposed parasympathetic (vagal) activity, causing increased peristalsis, leading to nausea.

405
Q

Triad of sodium nitroprusside toxicity

A

Elevated mixed venous oxygen

Tachyphylaxis

Metabolic acidosis

406
Q

Two drugs to consider avoiding in patients with reactive airway dz.

Why?

A
  • Morphine
  • Atracurium

Histamine release can induce bronchospasm

407
Q

Two factors that determine volume of distribution

A
  • drug size
  • electric charge

*small, nonpolar drugs have increased VoD

408
Q

Two factors that most affect spinal anesthetic spread/height

A

Baricity and patient position

409
Q

Type I error

A

Alpha, False positive

Accepted alternative hypothesis (Ha) but null hypothesis (Ho) is true (can’t be rejected)

410
Q

Type II error

A

Beta, False negative

Accepted null hypothesis (Ho) but alternative hypothesis (Ha) was true

411
Q

Ultrasound transducer frequency and depth of image

A

Increasing frequency of sound waves emitted increases image resolution but decreases the ability of the wave to penetrate deeper tissue.

412
Q

Ultrasound: Acoustic impedance

A

Determined by density of tissue and propagation speed of sound wave

413
Q

Ultrasound: Artifacts, Acoustic enhancement

A

Sound waves pass through low attenuation tissue- CSF, blood- allowing energy returning to probe from deeper structures that appear bright

414
Q

Ultrasound: Artifacts, Acoustic shadowing

A

Structures deep to tissues with high attenuation- bone, tendons- appear black because the reflection from more superficial structure blocks signal from deeper structures

415
Q

Ultrasound: Artifacts, Reverberation

A

Wave form bounces back and forth between two parallel interfaces causing multiple delayed signals to return to probe

416
Q

Ultrasound: Curved array probe vs. Linear array probe

A

Curved array probe maximizes returning ultrasound waves, allowing better visualization of deeper structures.

Linear array probes have higher frequency, better resolution but with less penetration and therefore, unable to better visualize deeper structures.

417
Q

Ultrasound: echodensity of tissue

A

Based on acoustic impedance (sound wave transmission vs sound wave reflection).

Echolucent/anechoic- increased transmission/conduction, appears BLACK due to high water content, ie: CSF, blood

Hyperechoic- increased reflection, appears bright/white, ie: bone, tendons, fascial planes

Hypoechoic- both absorption and reflection, appears gray, ie: fat and muscle

418
Q

Ultrasound: relationship between frequency, resolution and depth. Why?

A

Increasing sound wave frequency increases resolution but decreases depth (penetration) of image.

Higher frequency wave forms scatter more easily, depth increases scatter further.

419
Q

Uptake of inhaled anesthetics into different tissues from highest to lowest

A

Circuit > brain = alveoli > muscle > fat

420
Q

Vapor pressure is proportional to…

A

Temperature

421
Q

Ventilator/Pulmonary changes seen with (massive) CO2 embolism (likely in setting of insufflation)

A

Decreased EtCO2

Desaturation in pulse ox

No change in airway pressure

HoTN

422
Q

Ventilator/Pulmonary changes seen with capnothorax (likely in setting of insufflation)

A

Increased EtCO2

Desaturation in pulse ox

Increased airway pressures

Hyper-resonance

423
Q

Ventilator/Pulmonary changes seen with endobronchial intubation

A

Desaturation in pulse ox

Increased airway pressures

Unilateral decreased breath sounds

*EtCO2 is least sensitive indicator- may increase, decrease or have no change!

424
Q

Ventilator/Pulmonary changes seen with PTX

A

Decreased EtCO2

Desaturation in pulse ox

Increased airway pressures

425
Q

Ventilator/Pulmonary changes seen with subcutaneous emphysema 2/2 insufflation

A

Increased EtCO2

No change in pulse ox

No change in airway pressure

+/- crepitus

426
Q

What are the four processes of pharmacokinetics?

A

Absorption, distribution, biotransformation, excretion

427
Q

What are the motor functions of the glossopharyngeal nerve (CN 9)?

A

Stylopharyngeus muscle (dilates pharynx during swallowing)

Parotid gland

Glands of posterior tongue

428
Q

What are the sensory functions of the glossopharyngeal nerve (CN 9)?

A

Sensation to pharynx, middle ear, posterior 1/3 of tongue (taste buds), carotid body and sinus.

429
Q

What are the three main concepts of pharmacodynamics?

A

Potency, efficacy, therapeutic window.

It’s all about how the drug affects the body.

430
Q

What are the volumes of AMBU bags?

A

Adult: 1500 mL

Child: 500 mL

Infant: 250 mL

431
Q

What causes allergy to aminoamide LA?

A

Methylparaben (preservative ingredient)

432
Q

What effect does mixing lidocaine with propofol cause?

A

Lidocaine can destabilize the lipid emulsion of propofol and precipitate lipid droplets that, when >5 mcm can lead to embolism.

433
Q

What effect does N2O have on DNA?

Why is this important?

A

N2O irreversibly oxidizes cobalt atoms in vitamin B12, thereby rendering enzymes that are B12 dependent dysfunctional, including methionine synthetase necessary for myelin formation and thymidylate synthetase, responsible for DNA synthesis.

This is related to bone marrow suppression, megaloblastic anemia and peripheral neuropathy.

434
Q

What is a pneumotachometer?

Limitations?

A

Pneumotachometer is a type of fixed-orifice flowmeter. In this type of flowmeter, gas is channeled through a narrowed conduit, the narrowing increases resistance to flow dropping the pressure of gas as it exits. This pressure drop across resistance is proportional to the flow rate.

Limitation: only accurate when flow is laminar.

435
Q

What is a Q wave?

When is it pathologic?

A

Any negative deflection that precedes an R wave.

Bad= >40 ms/ 1 mm wide >2 mm deep >25% depth of QRS Observed in leads V1-V3

436
Q

What is central anticholinergic syndrome?

What is it similar to?

Treatment?

A

CAS is caused by anticholinergic medications that cross the BBB (scopolamine and atropine, due to tertiary amine structure).

It is similar to post-op delirium with symptoms including agitation, hallucinations, seizure, coma.

Tx= physostigmine, why? It is the only cholinesterase inhibitor that also has a tertiary amine structure and therefore crosses the BBB.

437
Q

What is methemoglobinemia?

Which drugs should be avoided?

A

Diminished enzyme reduction of methemoglobin back to hemoglobin because iron (Fe2+) has been oxidized to iron (Fe3+) and can’t carry oxygen.

Avoid prilocaine (EMLA cream), benzocaine, quinine, metoclopramide, sulfa drugs, dapsone.

438
Q

What is the action of the cricothyroid muscle?

Which nerve innervates it?

A

Tenses and ADDUCTS the vocal cords.

Innervated by the external branch of the superior laryngeal nerve.

439
Q

What is the afferent limb for the laryngospasm reflex?

A

Internal branch of the superior laryngeal nerve

440
Q

What is the benefit of ventricular hypertrophy?

A

Reduces ventricle wall tension.

441
Q

What is the corticobulbar tract?

A
  • Descending pathway, originates in the precentral gyrus, descends through corona radiata and genu of the internal capsule before terminating onto motor nuclei = cranial nerves
  • CN III, IV, V, VI, VII, IX, X, XI, XII
442
Q

What is the difference between SIADH and cerebral salt-wasting syndrome?

A

AVP secretion is normal in CSWS

443
Q

What is the increase in FiO2 per Liter of oxygen flow with a nasal cannula?

A

4% per Liter.

Max FiO2 obtainable with nasal cannula is 44% at 6L.

444
Q

What is the leading cause of mortality related to blood product transfusion?

Which blood product is most associated with this reaction?

A

TRALI

FFP > PRBC

445
Q

What is the major difference between laryngeal view grade IIa and IIb?

A

Vocal cords are no longer visualized with grade IIb view

446
Q

What is the major landmark for stellate ganglion blocks?

447
Q

What is the maximum FiO2 obtainable with a non-rebreather face mask?

A

FiO2 90%.

Why not 100%? Pt inspires a small amount of room air, otherwise if the oxygen supply was depleted, the patient would suffocate.

448
Q

What is the MELD score?

Why do I care?

Which components are used?

A

Score used to predict mortality in pts with end-stage liver disease.

Used to prioritize patients for liver transplantion.

Components= INR, creatinine, sodium, bilirubin, dialysis (I Crush Several Beers Daily)

449
Q

What is the Meyer-Overton rule?

A

An observation that inhaled anesthetic potency correlates directly with their lipid solubility.

450
Q

What is the most common cause of perioperative anaphylaxis?

A

Neuromuscular blocking agents

451
Q

What is the most common immune-related transfusion reaction?

Symptoms?

Treatment?

A

Urticarial allergic reaction (1-3% of all transfusions delivered)

Sx = urticaria and pruritus, airway is not typically involved

Tx = diphenhydramine + cont tranfusion

exception = if rxn affiliated with cardiovascular or pulmonary instability, STOP transfusion, provide supportive care

452
Q

What is the pathophysiology of anaphylaxis?

A

Type I hypersensitivity rxn, requires prior sensitization IgE binds antigen –> Fc receptor of Ige then binds to mast cells –> degranulation of histamine. leukotrienes, prostaglandins

453
Q

What is the primary acid-base buffer protein in blood?

A

Hemoglobin

Hgb takes up H+ ions when pH becomes acidotic and releases H+ ions when pH increases.

454
Q

What makes local anesthetics more potent?

A

Lipophilicity

455
Q

What may occur when giving supplemental oxygen to pt with COPD?

A

Worsening hypercapnia 2/2 V/Q mismatch (O2 decreases HPV in areas of lung that should be constricted b/c they are not ventilated well)

456
Q

Which abx interferes with metabolism of midazolam?

A

Erythromycin

457
Q

Which antibiotics can prolong duration of NMBA?

A

Aminoglycosides (Gentamicin, Neomycin)

Tetracylcins

Clindamycin

458
Q

Which antiplatelet drugs bind to ADP as their site of action?

A

Clopidogrel

Ticlopidine

459
Q

Which antiplatelet drugs bind to glycoprotein IIb-IIIa receptor as their site of action?

A

Abciximab

Eptifibatide

Tirofiban

460
Q

Which are the most effective ways to reduce pain on administration of propofol?

A

1: administer via antecubital vein

461
Q

Which area of thigh is not innervated by Femoral nerve?

Which nerve innervates this area?

A

Medial thigh

Obturator nerve (ventral rami of L2-L4), whereas Femoral nerve originates from the anterior rami of L2-L4

462
Q

Which areas are innervated by the Deep Peronal nerve?

A

Anterior compartment of lower extremity and dorsum of foot

463
Q

Which benzodiazepine metabolism is most affected by hepatic disease?

A

Diazepam (Valium) because a primary metabolite – desmethyldiazepam and 3- hydroxydiazepam – are physiologically active and prolong sedative effects.

464
Q

Which blood product is most susceptible to bacterial contamination?

465
Q

Which branch of CN X, vagus n. provides motor to cricothyroid muscle?

A

External branch of superior laryngeal n.

466
Q

Which branch of CN X, vagus n. provides sensory above the vocal cords?

A

Internal branch of superior laryngeal n.

467
Q

Which branch of CN X, vagus n. provides sensory below the glottis (trachea)?

A

Recurrent laryngeal n.

468
Q

Which cell type is most dependent on insulin for glucose uptake?

A

Cardiac myocytes

469
Q

Which cells myelinate nerve fibers in PNS? CNS?

A

PNS- Schwann cells

CNS- Oligodendrocytes

470
Q

Which class of local anesthetic has greater risk of allergic rxn? Why?

A

Esters- metabolized to PABA (para-aminobenzoic acid).

471
Q

Which class of local anesthetic has greater risk of systemic toxicity? Why?

A

Amides- metabolized by liver enzymes, whereas esters are broken down by esterases in plasma, therefore, have less time in systemic circulation to cause toxicity than amides.

472
Q

Which coagulation factors require Ca2+ for activation?

A

XIII –> XIIIa

X –> Xa

Prothrombin –> thrombin

473
Q

Which cranial nerve is responsible for the gag reflex?

A

CN IX, glossopharyngeal

474
Q

Which cranial nerves innervate the airway?

A

CN V, trigeminal- nose, nasopharynx

CN IX, glossopharyngeal- tongue –> upper epiglottis

CN X, vagus- larynx –> below epiglottis (trachea)

475
Q

Which drug class improves survival after myocardial infarction? Why?

A

ACE inhibitors

Block conversion of AT I to ATII, therefore, block production of aldosterone, effectively reducing afterload and prevent ventricular remodeling.

476
Q

Which drug class potentiates depolarizing blockade but blocks effect of non-depolarizing NMBA? How?

A

Cholinesterase inhibitors.

These inhibitors block enzyme degradation of AcH, thereby increasing [AcH] at synaptic cleft that further potentiates action of depolarizing agents.

By inhibiting cholinesterase activity, increased [AcH] is available to compete with NDNMBA action at AcH receptors thereby overcoming their blockade effects.

477
Q

Which drugs and/or hormones are metabolized in the lungs?

A
  • Norepinephrine
  • Propofol
  • Serotonin
  • Atrial natriuretic peptide
  • Endothelins
  • Adenosine
  • Bradykinin
478
Q

Which drugs and/or hormones are NOT metabolized by the lungs?

A
  • Epinephrine
  • Histamine
  • Dopamine
  • Isoproteronol
479
Q

Which electrolyte abnormalities are associated with chronic alcoholism?

A
  • Hyponatremia
  • Hypokalemia
  • Hypomagnesemia
  • Hyperuricemia
  • Respiratory alkalosis
480
Q

Which electrolyte abnormalities occur with thiazides?

A

Hyponatremia

Hypochloremia (metabolic alkalosis)

Hypokalemia

Hypercalcemia

481
Q

Which electrolyte abnormalities will occur with hyperventilation?

A

Hypokalemia

Hypocalcemia (increased calcium binding to negatively charged plasma proteins-albumin- as proteins release hydrogen ions to restore physiologic pH

Hypophosphatemia

482
Q

Which enzyme inhibitors increase risk of prolonging QT interval?

A

CYP3A4 (amiodarone, aprepitant, cyclosporine, diltiazem, verapamil, voriconazole, grapefruit juice, protease inhibitors- indinavir)

483
Q

Which enzyme is inhibited by Etomidate leading to adrenal suppression?

A

11-beta hydroxylase

484
Q

Which enzyme metabolizes mivacurium?

A

Pseudocholinesterase

485
Q

Which factor contributes to onset of local anesthetics?

486
Q

Which factor has the least effect on neuraxial blockade spread of spinal anesthetic?

A

Drug volume

487
Q

Which fire safety feature prevents microshock in the OR?

A

Equipment ground wire

How? It is a low impedance wire that allows current leakage to pass through to prevent buildup of leakage current.

488
Q

Which gases are not measured by Infrared absorption spectrophotometry?

Why?

A

Oxygen and Xenon

They are both non-polar molecules

489
Q

Which immunosuppresive agent is most likely to prolong non-depolarizing muscle blockade?

A

Cyclosporine

490
Q

Which inhaled anesthetic may cause QT prolongation?

A

Sevoflurane

491
Q

Which inhaled anesthetics inhibit NMDA activity?

A

N20, Xenon

492
Q

Which ions contribute to end-plate potential at the NMJ?

A

Sodium, calcium influx and potassium efflux

493
Q

Which isoenzyme is important in the metabolism of some inhaled anesthetics?

494
Q

Which lab test is best indicator of synthetic liver function? Why?

A

PT/INR

PT test extrinsic pathway, specifically factor VII, which has the shortest t1/2 of all clotting factors.

495
Q

Which lobe of the cerebral cortex is involved in the “fight-or-flight” response?

A

Limbic lobe, containing the hippocampus and amygdala

496
Q

Which local anesthetic racemic form is more cardiotoxic?

497
Q

Which local anesthetics carry the least risk of myotoxicity?

A

Tetracaine, procaine

498
Q

Which local anesthetic has the greatest risk of myotoxicity?

A

Bupivacaine

499
Q

Which muscle most closely correlates to abdominal muscle paralysis?

A

Corrugator supercilli muscle, innervated by facial nerve, causes movement of the eyebrow.

500
Q

Which nerve and muscle is responsible for vocal cord ABduction?

A

Recurrent laryngeal n. branch of CN X, vagus n. and posterior cricoarytenoid muscle.

501
Q

Which nerve and muscle is responsible for vocal cord ADduction?

A

Recurrent laryngeal n. branch of CN X, vagus n. and lateral cricoarytenoid muscle.

502
Q

Which nerve and muscle are most responsible for laryngospasm?

A

Nerve:

  • superior laryngeal nerve (CN X, vagus n.)

Muscle:

  • cricothyroid (causes vocal cord adduction)

*other muscles involved= cricoarytenoids, thyroarytenoids

503
Q

Which nerve innervates bicep muscle causing elbow flexion?

A

Musculocutaneous n.

504
Q

Which nerve is most likely to be injured during brachial artery cannulation?

A

Median nerve

505
Q

Which NMBA should not be used in pts with ESRD? Why?

A

Pancuronium

80% renal elimination

506
Q

Which opioid receptor has epileptogenic properties?

507
Q

Which opioid receptor mediates respiratory depression?

Muscle rigidity?

Hallucinations/dysphoria?

A

mu-2, mu-1, sigma (respectively)

508
Q

Which opioids are associated with serotonin syndrome? Why?

A

Meperidine, Tramadol, Methadone

They are considered weak serotonin reuptake inhibitors.

509
Q

Which parts of the aorta are most susceptible to chest wall injury? Why?

A
  1. Isthmus of the descending aorta (area of the arch between the left subclavian artery and ligamentous arteriosum)
    * arch is freely mobile but ligament anchors descending aorta, making it vulnerable to traction and tearing
  2. Aortic root
    * fixed by the diaphragm, therefore vulnerable to velocity changes
510
Q

Which pressor is most effective at treating refractory hypotension caused by ACE inhibitors?

A

Norepinephrine

511
Q

Which properties of opioids are resistant to tolerance?

A

Constipation and myosis

512
Q

Which sign is not seen with administration of glycopyrrolate? Why?

A

Mydriasis and sedation.

Glycopyrrolate is a quaternary molecule that is too big to cross the BBB, therefore, does not cause CNS side effects.

513
Q

Which skin layer acts as the drug reservoir for transdermal fentanyl?

A

Stratum corneum

514
Q

Which stereoisomer makes Etomidate clinically active?

A

R + isomer

515
Q

Which surgeries warrant discontinuing the use of aspirin perioperatively?

A

Intracranial surgery

Middle ear surgery

Posterior eye surgery

Intramedullary spine surgery (vertebrae)

Prostate surgery

516
Q

Which two parameters are required to calculate a drug’s volume of distribution?

A

Dose and plasma concentration

517
Q

Which valve prevents back filling/ transfilling between compressed-gas cylinders?

A

Check valve

518
Q

Which ventricles produce the majority of CSF?

A

Choroid plexus of the lateral and third ventricles

519
Q

Which vessels provide the highest degree of resistance in systemic vasculature?

A

Arterioles

520
Q

Why can NMBA act as allergens?

A

NMBA are divalent molecules and can cross-link IgE with resultant mast cell degranulation even without forming hapten-macromolecule complexes.

521
Q

Why do patients with flail chest develop hypoxia?

A

Underlying pulmonary contusion with increased elastic recoil of the lung, in setting of increased work of breathing.

522
Q

Why does chloroprocaine have such a rapid onset even though its pKa is 9?

A

It has a relatively high concentration (3%).

pKa is just one factor in onset of action for local anesthetics (lipid solubility and injection site are other variables that contribute to onset).

523
Q

Why does desflurane require a specialized vaporizer?

A

Variable bypass vaporizers used for sevo and iso are constructed for their unique vapor pressures, and rely on ambient temperature to continually vaporize liquid anesthetic.

Boiling point for sevo/iso is greater than room temperature, allowing ambient temp to act as energy source for vaporization.

Desfluranes boiling point is close to room temperature

524
Q

Why does dexmedetomidine cause cardiovascular depression?

A

Dex acts on centrally located alpha-2 receptors, activating presynaptic receptors in the locus ceruleus.

Alpha-2 receptors active inhibitory neurons, causing decrease in NT release. When this effects sympathetic neurons, catecholamine release is reduced resulting in decreased HR and BP.

525
Q

Why does pKa close to physiologic pH affect onset of action for local anesthetics?

A

pKa is the pH at which the fraction of ionized (acidic) and unionized (basic) drug is equal to each other.

When pKa is closer to physiologic pH (7.4), more drug is in the unionized (basic) form, which is the only form that penetrates the nerves cell membrane to create effect.

526
Q

Components of lethal triad (trauma)

A

Acidosis

Hypothermia

Dilutional coagulopathy

527
Q

Why is EMLA cream contraindicated in pts with congenital methemoglobinemia?

A

EMLA cream contains lidocaine and prilocaine.

Prilocaine is biotransformed into aminophenols which oxidize hemoglobin into methemoglobin.

528
Q

Why is succinylcholine contraindicated in pts with burn injury, massive trauma, neurological d/o and ESRD?

A

Risk of hyperkalemia.

Normal muscle releases enough potassium during sux induced depolarization to raise serum potassium by 0.5 mEq/L.

529
Q

Zero-order vs. first-order kinetics

A

Zero-order= a constant amount of medication is removed per unit time

First-order= a constant proportion/percentage of medication is removed per unit time; dependent on liver blood flow for elimination

Note: any drug can follow zero-order kinetics

ABA Basic Exam (1 decks)

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