PADI Dive Physiology and Health 3

Question 1

Oxygen toxicity affecting the central nervous system (CNS) is most likely at partial pressures above:

Accepted Answer

1.6 ATA

Answer

CNS oxygen toxicity risk increases significantly when the partial pressure of oxygen exceeds 1.6 ATA, which can cause convulsions.

Question 2

A diver using enriched air nitrox must calculate the maximum operating depth (MOD) to avoid:

Accepted Answer

CNS oxygen toxicity

Answer

Higher oxygen fractions in nitrox reach the 1.6 ATA oxygen partial pressure limit at shallower depths, so MOD must be calculated.

Question 3

Which symptom is a warning sign of CNS oxygen toxicity that a diver should recognize?

Accepted Answer

Visual disturbances or tunnel vision

Answer

Visual disturbances are among the early CNS oxygen toxicity warning signs remembered by the acronym VENTID-C.

Question 4

Pulmonary oxygen toxicity (the Lorrain Smith effect) results from:

Accepted Answer

Prolonged exposure to elevated oxygen partial pressures

Answer

Pulmonary oxygen toxicity develops with extended exposure to elevated oxygen and causes lung irritation and reduced vital capacity.

Question 5

Carbon dioxide buildup (hypercapnia) in a diver most commonly results from:

Accepted Answer

Breathing too slowly or skip breathing

Answer

Skip breathing reduces ventilation efficiency, causing CO2 to accumulate in the lungs and bloodstream.

PADI - Professional Association of Diving Instructors Practice Test