CFRN Physiology and Gas Laws 2

Question 1

According to Dalton's Law, if the total atmospheric pressure at sea level is 760 mmHg and oxygen comprises 21% of air, what is the partial pressure of oxygen (PaO2) at sea level?

Accepted Answer

159.6 mmHg

Answer

Dalton's Law states that the partial pressure of a gas equals its fractional concentration multiplied by total pressure (0.21 × 760 = 159.6 mmHg).

Question 2

A flight nurse is caring for a patient at 8,000 feet cabin altitude. Compared to sea level, which physiological change is expected in a healthy individual?

Accepted Answer

Increased respiratory rate to compensate for lower PaO2

Answer

At altitude, lower PaO2 stimulates peripheral chemoreceptors causing compensatory hyperventilation and increased respiratory rate.

Question 3

Which gas law explains why a pneumothorax can expand during flight as the aircraft ascends to altitude?

Accepted Answer

Boyle's Law

Answer

Boyle's Law states that at constant temperature, gas volume varies inversely with pressure; as cabin pressure decreases at altitude, trapped gas expands.

Question 4

The oxyhemoglobin dissociation curve shifts to the RIGHT in which of the following conditions encountered during flight?

Accepted Answer

Acidosis, hyperthermia, and increased 2,3-DPG

Answer

Acidosis, hyperthermia, hypercarbia, and increased 2,3-DPG shift the curve right, reducing hemoglobin's oxygen affinity and facilitating tissue oxygen release.

Question 5

Henry's Law is most clinically relevant for the flight nurse when managing a patient with:

Accepted Answer

Decompression sickness after SCUBA diving

Answer

Henry's Law states that the amount of gas dissolved in liquid is proportional to its partial pressure; decompression sickness results from nitrogen bubbling out of solution as pressure decreases.

CFRN - Certified Flight Registered Nurse Practice Test

CFRN - Certified Flight Registered Nurse Practice Test

CFRN Physiology and Gas Laws 2