[abstract] DECOMPRESSION FROM SHALLOW O2-N2 SATURATION EXPOSURES.

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[abstract] DECOMPRESSION FROM SHALLOW O2-N2 SATURATION EXPOSURES.

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Title: [abstract] DECOMPRESSION FROM SHALLOW O2-N2 SATURATION EXPOSURES.
Author: Hennessy, TR
Abstract: A review of various decompression profiles from shallow saturation exposures such as NOAA OPSII, SHAD, SCORE, Hydro-Lab and Air Sat II is presented. It is shown that the controlling tissue half-time is of the same order as the equivalent gas phase clearance half-time derived by Hennessy (1978)* from an analysis of bends following heliox saturation. It is also suggested that the above profiles fall into two classes. In the first class, the first stop is too shallow and early nucleation turns the ensuing profile essentially into a successful 'bubble treatment'. In the second, the initial stages follow too deep a course, with an inefficient outward gas elimination gradient, which also leads to a gas phase later in the decompression. To be successful, both cases require excessively long profiles. By carefully choosing the correct initial drop, followed by a continuous (linear) decompression, very much shorter decompression times should be possible. This hypothesis is being tested at Alverstoke as part of a UK Department of Energy contract. The first trial was a 15 m air saturation dive with the predicted profile consisting of a rapid decompression to 10 m followed by linear bleed at a rate of 60 min/m to 3 m, and a final rapid drop to the surface. Total decompression time was just over 7 hours, about one-third to one-half of that of current tables. Preliminary trials resulted in 7 successful man dives and 2 cases of bends occurring over 5 hours after surfacing. Modifications have been made to the profile and further trials are reported on. *Hennessy, T R, 1978. A mathematical model for predicting decompression sickness from saturation exposures. In Proceedings of the Symposium on the Effects of Pressure, Ed. S Daniels and H J Little, University of Oxford.
URI: http://archive.rubicon-foundation.org/4508
Date: 1979

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  • UHMS Meeting Abstracts
    This is a collection of the published abstracts from the Undersea and Hyperbaric Medical Society (UHMS) annual meetings.

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