[abstract] DECOMPRESSION RISK ANALYSIS COMPARING OXYGEN AND 50% NITROX DECOMPRESSION STOPS.

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[abstract] DECOMPRESSION RISK ANALYSIS COMPARING OXYGEN AND 50% NITROX DECOMPRESSION STOPS.

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Title: [abstract] DECOMPRESSION RISK ANALYSIS COMPARING OXYGEN AND 50% NITROX DECOMPRESSION STOPS.
Author: Walker, JR; Hobbs, GW; Gault, KA; Howle, LE; Freiberger, JJ
Abstract: Introduction: US Navy and Technical Divers commonly use oxygen or 50% Nitrox for accelerated decompression. 50% Nitrox as a single decompression gas has been proposed to be iso-risk with pure oxygen profiles where using 50% results in an overall shorter decompression time. We used validated probabilistic models to estimate the risk of DCS for planned decompression dives using oxygen or 50% Nitrox as a single decompression gas. Methods: Tables were produced for 32% nitrox dives with either 100% oxygen or 50% Nitrox for decompression. DecoPlanner decompression software (High Springs, FL) generated tables using two algorithms: Buhlmann with Gradient Factors and the Variable Permeability Model. Default software settings were used. Bottom times at 110fsw were limited to mandatory decompression dives, not to exceed the extreme exposure limits established in the US Navy Diving Manual. Three probabilistic models validated with US Navy dive outcome data (USN93, NMRI98, BVM3) were used to generate probability of DCS based risk profiles for dive tables planned with either VPM-B or Buhlmann-GF. Risk profiles were calculated for both algorithms using either 100% oxygen or 50% Nitrox for decompression stops terminating at 20fsw. The probability of DCS was plotted against the choice of algorithm and decompression gas while controlling for total dive and ascent time. Results: When time matched to control all variables except decompression gas, risk of DCS increased in all models when decompressing on 50% Nitrox. For VPM-B, the pDCS demonstrated a relative increase of 96.9% using the USN-93 model, 34.3% on BVM-3, and 20.6% on NMRI-98, using 50% Nitrox for decompression. Using Buhlmann-GF, the pDCS also demonstrated a relative increase of 84.1% with USN-93, 31.0% with BVM-3, and 18.7% with NMRI-98. Conclusions: Decompression using oxygen decreases the probability of DCS compared to decompressing with 50% nitrox, irrespective of overall decompression time.
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/8967
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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