Inwater Recompression: The Hawaiian Experience

by Richard L. Pyle

A little over ten years ago, Frank P. Farm, Edwin M. Hayashi, and Edward L. Beckman, from the Hyperbaric Treatment Center at the University of Hawaii School of Medicine conducted a survey of Hawaiian diving fisherman. The purpose of the survey, which was part of a Sea Grant Research project, was to chronicle the diving practices of Hawaii's fisherman, and to investigate their usage of inwater recompression therapy methods for the treatment of decompression illness (DCI). These fisherman, who regularly made five to eight dives per day, had collectively made over a quarter of a million dives at the time of the survey. As diving fisherman, their work entailed multiple daily exposures to 140-350 fsw (42-106 msw), followed by a shallow dive at the end of the day. With these profiles in mind, it should come as no surprise that everyone of them had suffered DCI at least once in their careers. In fact, most of them had experienced DCI many times; so many that it was considered part of the job&endash; an occupational hazard. To deal with this hazard, these diving professionals had, over the years, developed informal methods of inwater recompression therapy.

The survey revealed that these divers had utilized in-water therapyto treat DCI 527 times, and that the treatment completely eliminated DCI symptoms in 462 (88%) of the cases. In 51 of the remaining 65 cases, the divers had improved to the point where they opted not to seek further treatment and fully recovered in a day or two. The severity of the DCI symptoms treated with inwater methods ranged from mild shoulder pain to paralysis and other neurological dysfunction. The exact treatment methodology varied from diver to diver and there was no set standard. The divers included in the survey had made an average of 11,000 career dives (one had made over 23,000 dives), and had developed their diving regimes and inwater treatment methods by trial and error.

The somewhat remarkable results of the survey prompted the researchers to further investigate the effectiveness of inwater recompression therapy for use as an immediate, emergency treatment for DCI. Citing studies of bubble dissolution, growth dynamics and physiology, they attributed the high success rate of the inwater therapy to immediate recompression of the afflicted diver. They pointed out that the effectiveness of recompression therapy is greatly enhanced if recompression occurs within five minutes of the onset of symptoms.

The results of the survey were compiled in a report published by Sea Grant in 1986 (University of Hawaii Sea Grant Technical Paper UNIHI-SEAGRANT-TT-86-01). Melding the wisdom accumulated from the immense diving experience of the surveyed divers, and the results obtained from scientific studies on the physics and physiology of DCI and recompression therapy, Farm, Hayashi and Beckman formulated a list of conclusions and recommendations for Hawaii's commercial fisherman including a strong recommendation that oxygen be incorporated into in-water recompression regimes following the "Australian Method" developed by Dr. Carl Edmonds (see preceding article), or a modified version that was termed the "Hawaiian Method" (Note that the Hawaiian Method includes a "deep dip on air" to 165 fsw (50 msw) and, in the opinion of many authorities, is not recommended for technical divers, due to the logistics involved, and the fact that the additional nitrogen gas loading may outweigh the benefits of the additional pressurization&endash;ed.) They also point out that many factors should be considered before opting for inwater treatment, and it should considered only as an emergency treatment. Subsequent treatment at a hyperbaric facility should be sought in all cases, regardless of the outcome of the inwater therapy.

As a result of the work done in Hawaii, there appears to be interesting contrast between the attitudes of Hawaiian divers and those elsewhere. Whereas the practice of inwater recompression is either "unheard of" or strongly discouraged in many (most) parts of the world, it is considered a part of diving among Hawaii's diving fisherman and others, and there seems to be little controversy on the subject. Certainly not all divers are aware of it or consider it useful, but few dispute that it is a viable field option. Most of those who are aware inwater therapy are also aware of the dangers associated with it. Even so, among many groups, there is seldom much deliberation at the onset of DCI symptoms; conditions are assessed, and more often than not, in-water recompression is practiced, often with good results.

It's not that proper treatment is unavailable; Hawaii is home to an excellent hyperbaric facility which is only hours away from just about anywhere in the state. Hard-core Hawaiian divers simply have a different mindset with regards to the practice of inwater recompression. They view it as a viable procedure which has saved many lives, perhaps even their own.

Richard Pyle, aquaCorps field editor, is an ichthyologist and fish collector working with the Bishop Museum, Honolulu, and is currently completing his graduate studies at the Univ. of Hawaii. He can be contacted at: PO Box 19000A, Honolulu, Hawaii 96817. Fax: 808-841-8968.