Scuba Geek

CNS toxicity in closed-circuit oxygen diving: symptoms reported from 2527 dives. July 18, 2006

Posted by Andy Carroll in : Decompression , trackback

I found this interesting article on a blog called tenfootstop. It covers some research conducted by a group at the Israel Naval Medical Institute in Haifa, Israel and led by Dr.s Arieli, Shochat and Adir. The study examined dives done using a close circuit oxygen rebreather and sampled 2527 dives from 473 divers. The results follow;

No CNS oxygen toxicity-related symptoms were reported at a depth of 2 m seawater (msw), but their proportion increased at depths from 3 to 6 msw. We found that CNS oxygen toxicity-related symptoms appeared in 2.5% of dives conducted at a Po2 of 119 kPa. The main symptoms and signs reported were headache: 4.5%; nausea: 2.6%; hyperventilation: 2.6%; heavy breathing: 2.4%; dizziness: 1.6%; hiccups: 1.5%; bloody sputum: 1.4%; cold shivering: 1.1%; tinnitus: 0.9%; difficulty maintaining a steady depth: 0.9%; disorientation: 0.6%; tiredness: 0.5%; tingling in the limbs: 0.4%; hearing disturbances: 0.4%; a choking sensation: 0.4%; extreme effort: 0.4%; and loss of consciousness: 0.3%.

Generally the research hasn’t really provided any new information. Longer exposures increased symptoms, and some divers were more susceptible than others.