Talk:In-water recompression

From Wikipedia, the free encyclopedia
Jump to: navigation, search
WikiProject Scuba diving (Rated C-class)
WikiProject icon This article is part of WikiProject Scuba diving, an effort to create, expand, organize, and improve Scuba diving-related articles to a feature-quality standard.
C-Class article C  This article has been rated as C-Class on the quality scale.
 


Need clarification on O2 issues[edit]

This article reads to me as though treatment for IWR provides for recompression at 20 metres breathing pure Oxygen. But at that depth, pure oxygen would have a partial pressure of 3.0 ATA, massively higher than the acceptable level of 1.4 ATA and higher even that the technical diving contingency level of 1.6 ATA. The diver would tox in less than half an hour? Surely there must be some error in the way that it is phrased that need to be corrected? Or am I missing something? --Legis (talk - contribs) 15:04, 8 November 2008 (UTC)

The protocols are published as stated in the article. The key to getting your head around the depth is when these protocols were designed. Acceptable limits at the time most of these protocols were designed were higher than most of us would put our recreational risk these days. Treatment also assumes a need that is not evident in normal recreational/ technical diving. The other side of that is that even then they acknowledged a risk of oxygen toxicity among others (see the risks section of the article). Pyle's table does decrease the depth to 7.6 meters with oxygen toxicity concerns in mind but still remains deeper than most would operationally dive on oxygen to achieve a greater benefit from the higher pO2. This is one of those areas were any one variable can not be evaluated on it's own because success requires each step to be performed flawlessly and with the proper equipment. This is not a procedure that should be common or encouraged. I only took the time to illustrate and reference this article because it is done operationally and far more commonly than one would think. Most people I have talked to that have practiced this did it with no knowledge of any existing protocols or recommendations for their use. To quote the old NAUI moto, "safety through education" and this article is a great tool for conveying real information for those who may be interested in these tools. It is also worth note that the new 2008 US Navy Manual starts in water oxygen decompression at 15 meters, this is done with a hard hat. The US navy chamber treatment table 6 starts oxygen at 18 meters. It's just all about evaluating need, risk vs. benefit, and availability of resources on every dive and treatment. Hope this helps. --Gene Hobbs (talk) 15:56, 8 November 2008 (UTC)
Thanks. I should have known any article you had been involved in would cover it off pretty completely! --Legis (talk - contribs) 17:33, 8 November 2008 (UTC)
That is probably a little too strong. <g> Beware my "fixation errors". --Gene Hobbs (talk) 17:57, 8 November 2008 (UTC)
There are two important points to recognise: the first is that oxygen toxicity is by no means a given result - or even a predictable one. CNS toxicity is not likely in a resting diver, even breathing as much as 1.9 ATA oxygen (9 metres/30 fsw) for an hour. If you get a chance, have a look the incidence levels reported in Donald's "Oxygen and the Diver" (referenced with full text of the original articles in Oxygen toxicity). As Gene says, this is a matter of weighing up the (slim) chance of Oxtox against the certain damage of DCS where recompression facilities are a long way away. Secondly, consider the effect of an Oxtox hit. Given a full-face mask and a tender (as required), a hit is actually unlikely to be much more than an inconvenience, rather than life-threatening. All of this is not to say that there exists no danger of toxicity - but just as during in-chamber treatment (at 2.8 bar normally), the intention is that any (rare) incident is managed. BTW, the rebreather protocol would have the ppO2 regulated, so that's not part of this discussion. Hope that all makes sense :) --RexxS (talk) 03:43, 9 November 2008 (UTC)