[abstract] DECOMPRESSION RISK EVALUATION OF COMMERCIALLY AVAILABLE DESKTOP DECOMPRESSION ALGORITHMS

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[abstract] DECOMPRESSION RISK EVALUATION OF COMMERCIALLY AVAILABLE DESKTOP DECOMPRESSION ALGORITHMS

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Title: [abstract] DECOMPRESSION RISK EVALUATION OF COMMERCIALLY AVAILABLE DESKTOP DECOMPRESSION ALGORITHMS
Author: Hobbs, GW; Gault, KA
Abstract: Introduction: Probabilistic decompression models are used for decompression sickness risk calculation. We evaluated risks for profiles compared to three probabilistic models. These profiles represent typical dives planned and conducted by new technical divers. Methods: We produced decompression tables for 32% nitrox dives and a single 100% oxygen decompression gas. Bottom times were limited to the time one could safely dive using the “rule of thirds” on double E8-130 cylinders neglecting gas needed prior to oxygen breathing. The software and models tested include: DecoPlanner Buhlmann and Variable Permeability Model (VPM–B), GAP-Software, Reduced Gradient Bubble Model (RGBM), NAUTILUS DivePlanner DCAP and Hamilton-Kenyon Bubble Model (HKBM), and V-Planner VPM-B/E. Default software settings were used only modifying the last decompression stop depth to 20fsw. The models are three compartment decompression models that are parameterized to decompression data that includes the time of occurrence of decompression sickness. USN93 and BVM3 are fit to the same dataset, while NMRI98 was fit to an expanded data set including dives with high fractions of oxygen. USN93 and NMRI98 have risks as a function of compartment gas content, while BVM3's risks are a function of bubble volume. Profiles were calculated for all required decompression with a bottom time spacing of 10 minutes (depth fsw/time): 40/200; 50/180; 60/160; 70/140; 80/130; 90/120; 100/110; 110/110; 120/100; 130/90. Results: The percent risk predicted: BVM3, USN93, NMRI98; Buhlmann, 0.001-6.867, 0.018-5.002, 0.005-8.746; DCAP, 0.312-6.438, 0.338-4.026, 0.484-7.112; HKBM*, 0.023-7.057, 0.102-5.638, 0.178-9.452; RGBM, 0.391-8.01, 0.580-8.269, 0.591-11.791; VPM-B, 0.541-7.067, 0.682-5.688, 0.729-9.633;VPM-B/E, 0.372-6.95, 0.569-5.464, 0.589-9.401 * unable to calculate decompressions for shortest dives. Discussion: The profiles are not iso-risk. The maximum risk appears with greatest depth/ bottom time. The lowest risk was not necessarily on the shortest/ shallowest combination. Acknowledgements: Although the profiles used in this analysis were created with licensed copies of all software, the companies and individuals that created the software did not condone or review our methods or results. We would like to thank them for their hard work in making these tools available to divers. We would also like to thank Dr. David Doolette for his assistance.
Description: Abstract of the Undersea and Hyperbaric Medical Society, Inc. Annual Scientific Meeting, Las Vegas, Nevada, USA. (http://www.uhms.org)
URI: http://archive.rubicon-foundation.org/8233
Date: 2009

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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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