[abstract] THE EFFECT OF FINAL OXYGEN DECOMPRESSION STOP DEPTH ON DCS RISK: 20 FSW VS. 10 FSW.

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[abstract] THE EFFECT OF FINAL OXYGEN DECOMPRESSION STOP DEPTH ON DCS RISK: 20 FSW VS. 10 FSW.

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Title: [abstract] THE EFFECT OF FINAL OXYGEN DECOMPRESSION STOP DEPTH ON DCS RISK: 20 FSW VS. 10 FSW.
Author: Walker, JR; Hobbs, GW; Gault, KA; Howle, LE; Freiberger, JJ
Abstract: Introduction: US Navy and Technical divers commonly use oxygen for accelerated decompression with the last stop at 20fsw to take advantage of the increased partial pressure gradient of retained nitrogen. The relative risk of this practice, compared to traditional Navy profiles with a final 10 foot decompression stop, is unknown. We used validated probabilistic models to estimate the risk of DCS for planned decompression dives using oxygen with final decompression stop depths of 20fsw or 10fsw. Methods: Tables were produced for 32% nitrox dives and decompression with 100% oxygen. Bottom times at 110fsw were limited to decompression dives, not to exceed the extreme exposure limits in the US Navy Diving Manual. DecoPlanner decompression software (High Springs, FL) was used to generate tables using two algorithms: Buhlmann with Gradient Factors (B-GF) and the Variable Permeability Model (VPM-B). Default software settings were used except to adjust the depth of the last decompression stop to either 20fsw or 10fsw. Three probabilistic models validated with US Navy dive outcome data (USN93, NMRI98, BVM3) generated probability of DCS (pDCS) based risk profiles for dive tables planned with VPM-B or B-GF. The pDCS was plotted against the choice of algorithm and final stop depth while controlling for total dive and ascent time. Results: The pDCS for the USN93 model with VPM was decreased a maximum of 0.45% over all depth/time profiles with the last stop at 20fsw versus 10fsw. NMRI98 was iso-risk at the two final stop depths. BVM3 differed by 0.07% at the greatest point. For Buhlmann: USN93 pDCS decreased 0.39% at 20fsw, was unchanged for NMRI98, and reduced only 0.05% with BVM3 when compared to profiles with a 10fsw final stop. Conclusions: The probability of DCS on these profiles was not reduced by planning the last oxygen decompression stop at 20fsw instead of 10fsw.
Description: Abstract of the Undersea and Hyperbaric Medical Society, Inc. Annual Scientific Meeting, St Pete Beach, Florida, USA. (http://www.uhms.org)
URI: http://archive.rubicon-foundation.org/8966
Date: 2010

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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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