Dive Physiology and Health Flashcards

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

Answer: 1.6 ATA

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

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

Answer: CNS oxygen toxicity

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

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

Answer: Visual disturbances or tunnel vision

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

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

Answer: Prolonged exposure to elevated oxygen partial pressures

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

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

Answer: Breathing too slowly or skip breathing

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

Which condition describes insufficient oxygen delivery to body tissues, potentially causing unconsciousness?

Answer: Hypoxia

Hypoxia is a deficiency of oxygen reaching the tissues, which can lead to blackout, especially in breath-hold diving.

A freediver who hyperventilates before a breath-hold dive risks:

Answer: Shallow-water blackout due to hypoxia

Hyperventilation lowers CO2 without raising O2, suppressing the urge to breathe and leading to hypoxic blackout before CO2 triggers surfacing.