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Jason wrote: > [big snip. John Crea wrote this part] > > > > > > Divers found Bill's body approximately at the halfway point between ClearCut > > > and the next sink, lying on the guideline. His tanks (steel 104's) were > > > empty, and an empty aluminum 80 (stage bottle) was found about 50 -100ft > [another snip] > > > > John Crea - Chairman, NSS-CDS and NACD Accident files > > > > John, > > > > Your scenario is plausible but it doesn't readily > > explain why Bill's tanks were empty. Is there some type > > of "catastrophic medical disaster" that would have prevented > > Bill from exiting the cave but leaving him able to breath his > > tanks dry? > > > > Philip Weissman > > I have no idea if such a thing is possible or not. A non-medical > explination might fit the facts, though. I don't know what reg setup > Bill used, but is it possible (and plausible) that he lost conciousness, > and bumped the purge on some protuding rock? How rough are these cave > walls and floors? Just a thought. If, as John Crea surmised, Bill had an O2 hit we may have the following scenario. The process of a CNS O2 hit is something like: -------------- Begin Extract from the Nitrox Q&A -------------- 1. Pre-tonic build-up or pre-tonic premonition. This is the lead up to convulsions and may or may not be present or noticed. The symptoms are very similar to DCS and may include muscle twitching, nausea, hearing problems, tunnel vision, light headedness and breathing problems. If the symptoms do appear they may be followed so quickly by the next phase that the victim has no time to deal with the problem. It is also unlikely that the buddy will notice them either with all that diving gear (could you spot if your buddy's pupils were dilated?), especially if the victim is wearing a hood. 2. Tonic or rigid phase. The body goes completely rigid and the victim will stop breathing and lose consciousness. This phase may last from 30 seconds to 2 minutes. If the victim is taken to a shallower depth during this phase he may suffer lung barotrauma. 3. Convulsions. The victim is still unconscious but breathing restarts. It is at this point that the risk of drowning becomes a serious problem. As the body relaxes the victim's regulator could fall out of his mouth. 4. Post convulsive depression. The victim is still unconscious and breathing may be rapid and heavy. This can last anywhere from 5 to 30 minutes. 5. Conscious recovery. During this phase the victim may suffer amnesia, exhaustion, confusion and lethargy. -------------- End Extract from the Nitrox Q&A -------------- If Ariel witnessed the convulsions he may have either managed to keep Bill's regulator in his mouth or have replaced it when it fell out. If Bill then became unconscious Ariel may have decided to exit for help. It may be interesting to know whether Bill died of wet or dry drowning (I think that's the correct terminology - did he have water in his lungs bfore he died). Trying to deal with someone convulsing would probably use up substantial amounts of gas: from both exertion and stress. Ariel may have used up the stage bottle during this period and felt he didn't have enough to get them both safely out of the cave and so decided, quite rightly, to exit himself (or maybe he thought Bill was already dead). It is possible that the convulsions triggered something else, ie heart attack - as was surmised by someone else. Anyway, to answer your point. If Bill was lying in the cave unconscious he'd simply breath all his "air" away. Alan
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