Just about everybody is right in that IWR is not recommended, and if it is done, oxygen seems to be a key. On the other hand, the fact that there are at least 6 published protocols on how to do it more than suggests that it is at least controversial. The Rubicon article above refers readers to the Wikipedia article, to which they contributed:
In-water recompression - Wikipedia, the free encyclopedia. It is a pretty good article.
Here is something else to read, an article by Dr. Richard Pyle, who has personal experience with in-water recompression:
http://www.angelfire.com/ca/divers3/IWR.pdf. Here is a an interesting portion:
Indeed, even among authors who discuss IWR, the
vast majority condemn the practice of using air as a breathing mixture. The source of this
condemnation appears to stem from the commonly-held believe among hyperbaric specialists that
breathing air during IWR attempts tends to worsen symptoms more often than it improves them (11,
30). However, the empirical foundation of this widespread believe has been called into question
(31). Published survey data of diving fishermen in Hawaii (4) indicate an apparently very high rate
of success (in terms of symptom elimination or improvement) when using air as a breathing mixture
for IWR (Figure 1).
I think it can be a tough call if you are in a really bad situation, like 24 hours from potential help. (Yes, that can happen if you are on a liveaboard at the far end of the Galapagos, for example.) Two years ago in Cozumel, Opal Cohen got back in the water with DCS symptoms. Her boat was waiting for other divers to surface, and she decided she could not wait. I think most people would agree that the better course of action would have been to find some way to get her to shore and into the chamber as soon as possible, and we will never know if she would have lived had that happened and she had gotten effective treatment earlier. In that case, her treatment would have been delayed only an hour at most had she not gone back in the water, but what if we are talking about a very serious delay in treatment and the possibility of death in the meantime? What would you do? In another article by Pyle I read some time ago and cannot find now, he describes an interesting incident in which three divers got bent in a situation where they had a very long delay facing them before treatment. One of them insisted on being put back in the water for a while, receiving a very informal treatment that way. He was the only one of the three who lived.
The end of the Wikipedia article includes this comment about what they call informal treatment, referring to the DAN 2008 article:
Although in-water recompression is regarded as risky, and to be avoided, there is increasing evidence that technical divers who surface and demonstrate mild DCS symptoms may often get back into the water and breathe pure oxygen at a depth 20 feet/6 meters for a period of time to seek to alleviate the symptoms. This trend is noted in paragraph 3.6.5 of DAN's 2008 accident report.[16]The report also notes that whilst the reported incidents showed very little success, "[w]e must recognize that these calls were mostly because the attempted IWR failed. In case the IWR were successful, [the] diver would not have called to report the event. Thus we do not know how often IWR may have been used successfully."
In other words, they have reports of IWR attempts that did not work, but they don't know about reports that did work and were not reported. People tend not to call them when things go right. As it turns out, I know of three successful IWR incidents following technical dives, all using oxygen, full-face masks, and one of the established protocols (not sure which one). I was not present for any of them, but it was with a group of divers and location with whom and where I was diving regularly in those days. I know the diving agency involved in those dives was actually considering creating a course in IWR, at least according to the instructor present at that location who supervised the IWR, but they decided against it.
