[abstract] OPTIMAL DECOMPRESSION PROFILES BASED ON NONLINEAR DYNAMIC BUBBLE MODELS A NEW UNDERSTANDING OF SAFETY STOPS

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[abstract] OPTIMAL DECOMPRESSION PROFILES BASED ON NONLINEAR DYNAMIC BUBBLE MODELS A NEW UNDERSTANDING OF SAFETY STOPS

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Title: [abstract] OPTIMAL DECOMPRESSION PROFILES BASED ON NONLINEAR DYNAMIC BUBBLE MODELS A NEW UNDERSTANDING OF SAFETY STOPS
Author: Gutvik, CR; Brubakk, AO
Abstract: BACKGROUND: The aim of any decompression procedure is to ascend to the surface as fast as possible without a significant risk of injury. We have previously demonstrated a framework for calculating optimal profiles (Gutvik et al, UHM 2004:31;342), which now has been implemented on a dynamic bubble model (Copernicus). MATERIALS AND METHODS: The Copernicus model predicts the total spectrum of vascular bubbles distributed in body tissues, and the total volume of released gas phase is a reasonable indicator on decompression stress (Yount). For comparison, a 27msw/22min and 30msw/40min air dive were simulated using a safety stop at 3msw/5min and the generated decompression stress was determined. An optimization problem was formulated to minimize the stop time subject to a designed constraint in generated stress, which calculates the optimal stop time and stop depth. Two different calculations were performed on both dives. First we used the generated stress from the reference dives as constraint and extended the bottom time until the stop time reached the same as the reference stop (5 min). Secondly we kept the bottom times the same as for the reference dives and lowered the stress constraint until the calculated stop time reached 5 min. RESULTS: The current model parameters in Copernicus give a decompression stress of 7.5 for the 27 msw/22 min dive and 75 for the 30 msw/40min dive using the 3msw/5min safety stop. The stress could be reduced by 10-35percent by performing an optimal stop at 9msw/5min instead of the traditional stop. Alternatively, the bottom time could be extended by 2-4 min by performing an optimal safety stop at 9msw for 5minutes without exceeding the originally generated stress. CONCLUSIONS: Using optimization theory on the decompression problem gives a new insight how decompression schedules influence gas dynamics and decompression stress. The safety stop example presented here can easily be extended to define optimal decompression schedules.
Description: Undersea and Hyperbaric Medical Society, Inc. (http://www.uhms.org )
URI: http://archive.rubicon-foundation.org/1693
Date: 2005

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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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