What should be done if a patient suffers from CNS O2 toxicity after ascending 10 feet?

In the case of a patient experiencing central nervous system (CNS) oxygen toxicity, particularly after a relatively minor ascent such as 10 feet, the appropriate action is to finish decompression on chamber air. This response is grounded in the understanding of how oxygen toxicity occurs and its management.

CNS oxygen toxicity can manifest when divers or patients breathe high concentrations of oxygen under pressure. If a diver ascends to a level where the partial pressure of oxygen decreases significantly, the symptoms related to CNS toxicity may resolve. By completing decompression using chamber air, which contains a lower partial pressure of oxygen compared to pure oxygen, the risks associated with elevated oxygen levels are mitigated. This approach allows for a safer transition back to surface pressure without exacerbating the toxicity.

Increasing oxygen levels in the chamber would not be appropriate since it would likely worsen the symptoms of CNS toxicity. Administering additional nitrogen could potentially complicate the situation without addressing the immediate concern of oxygen toxicity. Commencing an emergency ascent should also be avoided because rapid ascents can lead to other complications, including decompression sickness.

Thus, the correct course of action is to finish decompression using chamber air, providing a safer environment for alleviating oxygen toxicity symptoms and preventing further complications.