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>Hi Folks > After following this thread for a while I have a question. If you are >correctly(sic) set up for OWR with a FFM etc and you are down as a tender. If >the diver under treatment does go into convulsions due to O2 tox what is the >correct procedure? Someone mentioned that you should never bring a convulsing >diver to the surface due to the risk of embolism, if you do not have the >ability to switch the gas that the diver is breathing, will the convulsions >continue while the diver is under pressure and breathing O2? I am not aware if anyone has tried to continue administering O2 beyond the point of convulsion in humans or animals, but neurophysiological preparations in vitro continue to manifest hyperexcitability throughout HBO treatment. It is reasonable, considering the aetiology of CNS O2 toxicity, to assume that if HBO were continued the diver would have further convulsions. >Does this mean >that you must have the ability to switch gasses before considering IWR. The convulsion is a sign of serious central nervous toxicity, oxygen must be discontinued before any more damage is done. Certain areas of the brain can be damaged by the seizure activity that underly such convulsions, although convulsions do not mean that such areas are experiencing seizures, but given the epileptogenic potential of these areas, I wouldn't be suprised (I must look that up). Furthermore, the seizure/convulsions are only one sign of the underlying pathology of O2 toxicity, continued free radical generation and lipid peroxidation etc., as a consequence of continued HBO, will cause neurone damage. You must be able to switch gases. I believe Jason Rogers recently posted a protocol for dealing with in-water CNS O2 toxicity. Such protocols are published in, for instance, the DCIEM manual. >P.S. has someone done the calculations for the AusIWR table for the aprox >number of cu ft of O2 that would be required to complete the treatment.(I >know I am being lazy but my brain has shut down for the holidays). I posted this at the beginning of this thread. 138-198 minutes, 9msw max depth, 5-10 litres/min/bar gas consumption on demand, worst figure is 3762 litres, who knows how many cu ft that is, this is Australia after all, about 150 I would say. >If you >were to consider the use of an O2 rebreather for the treatment, how often >would you have to flush the loop? regards, David Doolette ddoolett@me*.ad*.ed*.au*
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