Which factor can increase susceptibility to CNS oxygen toxicity?

Rapid exercise combined with the buildup of carbon dioxide can significantly increase the risk of central nervous system (CNS) oxygen toxicity. During intense physical activity, the body metabolizes oxygen more quickly and produces more carbon dioxide. This increased level of carbon dioxide can contribute to a condition known as hypercapnia, which can subsequently enhance the potential for oxygen toxicity effects on the CNS.

When a diver breathes high concentrations of oxygen, as is often the case with Nitrox, and experiences elevated carbon dioxide levels, the body’s sensitivity to oxygen can increase. High concentrations of oxygen can lead to the production of reactive oxidative species, which in conjunction with the physiological changes induced by carbon dioxide, can elevate the risk of CNS toxicity, manifesting in symptoms such as convulsions or other neurotoxic effects.

In contrast, while high altitude and rapid ascent might pose their own risks to divers, they do not directly correlate with an increased susceptibility to CNS oxygen toxicity in the context of enriched air diving compared to the effects of heavy exercise and carbon dioxide buildup. Cold water exposure primarily affects thermoregulation and does not have a significant impact on CNS oxygen toxicity risk in this scenario.