Fine, on an air dive to 293', ppo2 of 2.05. In the past 10 years we have done 9,256 hyperbaric treatments. Of those patients, 2,578 had a maximum ppo2 of treatment between 2.0and 2.2. Seven of those patients had seizures. 2 were male, 5 female. These patients were usually normothermic, and not physically exerting themselves. But, they were frequently physically debilitated. If any estimation of risk of oxygen induced seizure can be made from this patient population, the incidence of having an O2 seizure at 293' on air would be low. As the treatment ppO2 increases, the seizure incidence greatly increases. It is unkown if subjects in a hyperbaric chamber are a good analog for divers when studying oxygen toxicity and HPNS. They have been shown to be a reliable analog for studying microbubble formation when stratified for core temperature and heart rate (we record the divers core temp and HR at resolution of the dive, and record carotid and precordial doppler signatures, then we subsequently put the same divers in the chamber, and try to replicate the dive profile, and again record doppler signatures). Of course , these days, any studies on seizure threshold must be done retrospectively due to risk of the seizure (outside of porcine and canine analogs). We can't just throw a few seamen in the pot and crank it like they did in the good old days.
