What is the chief sign of CNS oxygen toxicity that may lead to drowning?

CNS oxygen toxicity is a serious condition that can occur when a diver experiences elevated partial pressures of oxygen, primarily when using enriched air nitrox or when diving at significant depths. The chief sign of this condition is convulsions, which can be sudden and unpredictable. When a diver experiences a convulsion underwater, the immediate risk of drowning is high, as the loss of motor control and consciousness can prevent the diver from maintaining buoyancy or returning to the surface.

Understanding the implications of convulsions in this context is critical for divers. The onset can be triggered by various factors, including depth, exposure time, and the partial pressure of oxygen in the breathing mix. Recognizing these symptoms is vital for safety; divers must be aware of the risks associated with prolonged exposure to high levels of oxygen.

In contrast, while joint pain, itchiness of the skin, and visual impairment can be associated with other conditions or concerns in diving, they do not lead to an immediate risk of drowning in the same way that convulsions do. This highlights the importance of monitoring for CNS toxicity signs and having a clear understanding of the most critical symptoms that require immediate action.