Stanford CA-1 Prep (Inhalational Agents)

Question 1

The pressure of a volatile anesthetic in the alveoli is in equilibrium with where else?

Answer 1

P_alveoli = P_blood = P_CNS =

Question 2

At higher altitudes (where P_atm < 760mmHg), the same concentration will exert a ______ partial pressure and thus have a _______ anesthetic effect.

Answer 2

lower : reduced

Question 3

The ______ _______ of a VAA yields effect, not concentration.

Answer 3

partial pressure

Question 4

What effect would low blood solubility have on VAA uptake?

Answer 4

Low solubility → low saturation → taken up more quickly by the CNS → faster induction.

Question 5

What effect would high cardiac output have on VAA induction?

Answer 5

↑ CO → quick to brain, but quicker “washout”

Question 6

Gasses with the ______ solubility with have the fastest rate of F_A/F_I increase and thus a faster induction.

Answer 6

lowest

Low gas solubility means it isnt dissolving and getting “stuck” in the blood, it makes its way to the CNS quicker.

Question 7

What gas has the greatest F_A/F_I ratio?

Answer 7

N₂O

Question 8

What type of shunt (left to right or right to left) will cause a greater change in induction speed using VAA’s?

Answer 8

Right to Left Shunt.

Shunted blood mixes with VAA blood → diluted anesthetic partial pressure → slowed onset of induction.

Question 9

What are the MAC values of the following:

• N₂O
• Desflurane
• Isoflurane
• Sevoflurane

Answer 9

• N₂O = 104%
• Desflurane = 6.8%
• Isoflurane = 1.17%
• Sevoflurane = 1.8%

Question 10

What factors will increase the rate of rise of the F_A/F_I ratio?

Answer 10

• Low VAA solubility
• Low CO
• High minute Ventilation

Question 11

Which of the following is true about F_A/F_I when cardiac output in doubled?

A. increasing cardiac output has no significant effect on anesthetic uptake.
B. FA/FI ratio rises faster for soluble agents than insoluble agents.
C. FA/FI ratio rises slower for soluble agents than insoluble agents.
D. the rate of rise is the same for insoluble and soluble agents.

Answer 11

C. FA/FI ratio rises slower for soluble agents than insoluble agents.

Question 12

What receptors are affected by VAA?

Answer 12

• GABA (likely causing ↑ Cl⁻ conductance)
• NMDA
• Glycine

Question 13

What are the effects of VAA administration on CBF, ICP, and CMRO₂?

Answer 13

• ↓ CMRO₂
• ↓ cerebral vessel resistance → ↑ CBF and thus ↑ ICP

Question 14

How will VAA effect our hemodynamics?

Answer 14

↓ SVR and thus ↓ MAP (but CO is maintained)

Question 15

What are the pulmonary effects of VAA administration?

Answer 15

↓ V_T , ↑ RR → preserved V̇_T

Question 16

What effect do VAA have on the renal system?

Answer 16

↓ renal blood flow = ↓ GFR

Question 17

Which VAA is not a trigger for malignant hyperthermia?

Answer 17

N₂O

Question 18

Air should periodically be let out of the ______ ______ if using N₂O to avoid injury.

Answer 18

ETT cuff

Question 19

Which VAA, when exposed to CO₂ absorbent, breaks down into compound A?

Answer 19

Sevoflurane

Not really clinically relevant.

Occurs in soda lime but not Ca⁺⁺ hydroxide.

Question 20

Which VAA is more likely to form CO in dessicated absorbent?

Answer 20

Desflurane.

Question 21

Desflurane can cause an _____ response when inspired concentration is increased rapidly.

Answer 21

SNS