Baby Miller Potpourri

Question 1

Weight scalar for propofol bolus in obese patient?

Answer 1

Lean Body Mass = 1.1 x Total Body Weight - 128 (TBW/Ht)^2

Question 2

Weight scalar for propofol infusion in obese patient?

Answer 2

Adjusted Body Weight = Ideal Body Weight + 0.4( (TBW-IBW)

Question 3

Formula for Ideal Body Weight for Males? Females?

Answer 3

Male: 50kg + 2.3kg for each inch above 5ft
Female: 45.5kg + 2.3kg for each inch above 5ft

Question 4

Lean body mass formula

Answer 4

Lean Body Mass = 1.1 x Total Body Weight - 128 (TBW/Ht)^2

Question 5

Adjusted body weight formula

Answer 5

Ideal Body Weight (50kg + 2.3kg for each inch above 5ft) + 0.4(TBW-IBW)

Question 6

Weight scalar for non-propofol IV sedative boluses?

Answer 6

Total Body Weight

Question 7

Weight scalar for non-propofol IV sedative infusions?

Answer 7

Ideal Body Weight

Question 8

What is the one weight scalar that underdoses remifentanyl in obese patients (esp. morbidly obese)? Why?

Answer 8

Lean Body Mass, the calculated mass starts to decrease above 127kg TBW

Question 9

Three phases of three multicompartment pharmacokinetic model after fentanyl bolus?

Answer 9

Rapid distribution, slow distribution, and terminal phase

Question 10

Definition on context sensitive half time?

Answer 10

It is the 50% decrement time (time to reach 50% of plasma concentration after infusion terminated)

Question 11

What is an isobole?

Answer 11

Isoeffect line for a selected probability of effect.

Question 12

Mean arterial pressure formula

Answer 12

MAP = SVR x CO

Question 13

Systemic Vascular Resistance formula

Answer 13

SVR = 80 x (MAP-CVP)/CO

Question 14

Cardiac output formula

Answer 14

CO= HR x Stroke volume

Question 15

Cardiac index formula

Answer 15

Cardiac output / body surface area

Question 16

Three measurements that can be used to assess preload

Answer 16

Left atrial pressure, pulm capillary wedge pressure, pulmonary arterial diastolic pressure

Question 17

List causes of decreased preload (4)

Answer 17

hypovolemia (hemorrhage, fluid losses), venodilation (anesthetics, neuraxial), tension pneumo, pericardial tamponade

Question 18

Describe Bainbridge reflex

Answer 18

Atrial stretch -> increased HR (helps match CO to venous return)

Question 19

Percent of coronary blood oxygen extraction? How does this compare to normal total body extraction?

Answer 19

60-70%, compared to 25%

Question 20

Name 3 endogenous regulators of coronary blood flow

Answer 20

adenosine, nitric oxide, adrenergic stimulation

Question 21

formula for LV perfusion pressure

Answer 21

DBP - LVEDP

Question 22

What blood vessels contribute to pulmonary vascular resistance?

Answer 22

Large arteries, small arteries, AND capillaries

Question 23

List normal and pathologic pressure ranges for CVP, Pulm art. systolic, pulm art diastolic, pulm art mean, and PCWP

Answer 23

CVP 2-8, >18 pathologic
PAS 15-30, >40 pathologic
PAD 4-12, > 20 pathologic
PAM 9-16, > 35 pathologic
PCWP 4-12, > 20 pathologic

Question 24

Describe the three West zones of the lung in terms of airway pressures, pulm arterial pressures, and pulm venous pressures

Answer 24

Zone 1: airway pressures > both PAP and pulm venous pressures
Zone 2: PAP > airway pressure > PVP
Zone 3: both PAP and PVP > airway pressures

Question 25

Normal adult oxyhemoglobin p50 (mmHg)

Answer 25

26.8 mmHg

Question 26

List factors causing a left shift in oxyhemoglobin dissociation curve.

Answer 26

alkalosis, hypothermia, decreased 2,3 DPG (stored blood), fetal hemoglobin

Question 27

List factors causing a R shift in oxyhemoglobin dissociation curve

Answer 27

acidosis, hyperthemia, hypercapnea, increased 2,3 DPG (chronic arterial hypoxemia or anemia)

Question 28

Arterial oxygen content formula

Answer 28

Ca02 (mL/dL) = Sa02 (Hb x 1.39) + 0.003(Pa02)
Note: 1.39 mL of 02/ gram hemoglobin, 0.003 mL 02/dL/mmHg is oxygen solubility

Question 29

Alveolar Gas Eqn

Answer 29

PA02 = FI02 x (Barometric pressure - water vapor pressure) - Pc02/RQ
RQ = 0.8, normal barometric 760mmHg, normal water vapor pressure 47mmHg

Question 30

Normal adult oxygen consumption (mL/min)

Answer 30

300 mL/min

Question 31

A-a gradient formula? What does it reflect? Important limitation?

Answer 31

A-a gradient =PA02 - Pa02. It reflects venous admixture. Limitation: most accurate on room air

Question 32

What equation estimates dead space ventilation ratio?

Answer 32

Bohr equation: VD/VT = (PaC02 - PetC02)/PaC02

Question 33

Formula for dynamic lung compliance

Answer 33

Tidal volume / (Peak airway pressure - PEEP)

Question 34

Formula for static lung compliance

Answer 34

Tidal volume / (Plateau airway pressure - PEEP)

Question 35

List 6 contributors to airway resistance

Answer 35

radius of airway, smooth muscle tone (spasm, inflammation), foreign bodies, compression of airways, turbulent gas flows, anesthesia equipment

Question 36

What signals do carotid bodies sense? (3) (peripheral chemoreceptors for ventilatory drive)

Answer 36

P02, high Pc02, low PH (including metabolic acids)

Question 37

Fick Eqn

Answer 37

V02 = CO x (Ca02 - Cv02)

Question 38

CCB that decreases MAC requirements?

Answer 38

Verapamil

Question 39

Factors Determining Partial Pressure Gradients Necesssary for establishment of Anesthesia

Answer 39

1. Transfer of inhaled anesthetic from anesthetic machine to alveoli (Inspired partial pressure, alveolar ventilation, breathing system characteristics)
2. Transfer of inhaled anesthetic from alveoli to arterial blood (blood-gas partition coefficient, cardiac output, alveolar-to-venous partial pressure delta)
3. Transfer of inhaled anesthetic from arterial blood to brain (brain-blood coefficient, cerebral blood flow, arterial to venous partial pressure difference)

Question 40

Enzyme inactivated by nitrous oxide?

Answer 40

Methionine synthase (b12 and folate metabolism), can lead to elevated homocysteine levels -> more adverse cardiac events after carotid endarterectomy