ABA Anesthesia Principles & Practices 2

Question 1

Which mechanism best explains the MAC-sparing effect of nitrous oxide when combined with volatile anesthetics?

Accepted Answer

Competitive NMDA receptor antagonism reduces overall anesthetic requirement

Answer

Nitrous oxide's NMDA antagonism provides additive analgesia and sedation, reducing the MAC requirement of co-administered volatile agents.

Question 2

A patient with severe mitral stenosis presents for elective surgery. Which hemodynamic goal is MOST important during anesthetic management?

Accepted Answer

Maintain sinus rhythm and avoid tachycardia

Answer

Mitral stenosis limits diastolic filling; tachycardia reduces diastolic time further, causing acute pulmonary edema, so rate control and sinus rhythm are paramount.

Question 3

The phenomenon of 'diffusion hypoxia' after nitrous oxide discontinuation is primarily caused by:

Accepted Answer

Rapid outward diffusion of N2O diluting alveolar oxygen

Answer

Large volumes of N2O rapidly diffuse from blood into alveoli, diluting both oxygen and CO2, necessitating supplemental oxygen at emergence.

Question 4

Which property of a local anesthetic MOST determines its duration of action?

Accepted Answer

Protein binding percentage

Answer

Higher protein binding correlates with prolonged duration because the drug remains sequestered at the sodium channel protein, delaying redistribution.

Question 5

During one-lung ventilation, hypoxemia persists despite 100% FiO2. The MOST effective next intervention is:

Accepted Answer

Apply CPAP (5-10 cmH2O) to the non-ventilated lung

Answer

Low-level CPAP to the non-dependent lung maintains partial alveolar recruitment while still allowing surgical access, improving V/Q matching.

(ABA) ASA (American Society of Anesthesiologists) Board Certification Practice Test

(ABA) ASA (American Society of Anesthesiologists) Board Certification Practice Test

ABA Anesthesia Principles & Practices 2