CFRN Physiology and Gas Laws 3

Question 1

A CFRN is transporting a patient with a closed bowel obstruction. At altitude, this patient is most at risk for which complication based on gas law principles?

Accepted Answer

Bowel distension and perforation due to gas expansion

Answer

Boyle's Law predicts trapped intestinal gas expands as cabin pressure decreases, increasing the risk of bowel distension and potential perforation.

Question 2

Charles' Law describes the relationship between gas temperature and volume. This law is most relevant during aeromedical transport when:

Accepted Answer

Assessing expansion of air splints in cold weather

Answer

Charles' Law (volume varies directly with temperature at constant pressure) is relevant for air splints, which may contract in cold temperatures and require reassessment.

Question 3

During aeromedical transport, which factor does NOT directly contribute to hypoxic hypoxia in a patient?

Accepted Answer

Carbon monoxide binding to hemoglobin

Answer

Carbon monoxide binding to hemoglobin causes hypemic (anemic) hypoxia, not hypoxic hypoxia, which specifically refers to inadequate oxygen in the inspired gas reaching alveoli.

Question 4

A patient's pulse oximeter reads 92% SpO2 during flight at cabin altitude equivalent to 8,000 feet. The flight nurse knows that the actual PaO2 is approximately:

Accepted Answer

60 mmHg

Answer

An SpO2 of 92% corresponds to approximately 60 mmHg PaO2 on the oxyhemoglobin dissociation curve, which is the critical inflection point.

Question 5

Graham's Law states that the rate of diffusion of a gas is inversely proportional to the square root of its molecular weight. This explains why:

Accepted Answer

Carbon dioxide diffuses 20 times more readily across the alveolar membrane than oxygen

Answer

CO2 has greater solubility (approximately 20× more soluble than O2) and diffuses across the alveolar-capillary membrane much more readily than oxygen.

CFRN - Certified Flight Registered Nurse Practice Test

CFRN - Certified Flight Registered Nurse Practice Test

CFRN Physiology and Gas Laws 3