Confusion during a dive can be a sign of which of the following?

• A. Hypoxia
• B. Hypercapnia
• C. Oxygen toxicity
• D. All of the above

Answer: (D)

Confusion during a dive signals that brain function is being affected by the breathing gas or its delivery. If the brain doesn’t get enough oxygen (hypoxia), mental function declines quickly, leading to confusion and poor judgment. If ventilation is inadequate or carbon dioxide builds up (hypercapnia), the result is cerebral irritation and disorientation. And when oxygen levels become too high at depth (oxygen toxicity), the central nervous system can be stimulated in ways that cause confusion, dizziness, or even seizures. Because confusion can arise from any of these gas-related problems, all of the above is the best answer.