[abstract] MECHANISTIC ANALYSIS OF THE RISK OF DECOMPRESSION SICKNESS AT ALTITUDE.

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[abstract] MECHANISTIC ANALYSIS OF THE RISK OF DECOMPRESSION SICKNESS AT ALTITUDE.

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Title: [abstract] MECHANISTIC ANALYSIS OF THE RISK OF DECOMPRESSION SICKNESS AT ALTITUDE.
Author: Van Liew, HD; Burkard, ME; Conkin, J
Abstract: BACKGROUND: With maximum likelihood in risk-function format, it is possible to test hypotheses about the underlying mechanisms of decompression sickness (DCS). METHODS: We fit models to selected data from groups of men in altitude chambers (Aviat Space Environ Med 1992;63:819-824); the response variable was whether or not subjects had DCS serious enough to terminate their exposures; the independent variables were duration of O2 prebreathing, time at altitude, and altitude pressure. The models embodied several assumptions: a) decompression risk is positively related to the volume of N2 that can be released from solution at the barometric pressure of the altitude, but not necessarily directly proportional to it, b) risk is also positively related to pressure drop (this can mean that risk depends on the number of bubbles which form), c) there is no risk if the supersaturation does not exceed a threshold, d) O2 breathing before decompression washes N2 out of the relevant tissue, and e) risk increases with time at altitude. RESULTS: Incorporation of each of the mechanistic assumptions into models improves the fit of the data. Risk increases with the amount of releasable N2 raised to a power greater than 1.0; for example, one of the risk terms in the better models is approximately [(P1N2-P2-m) / (P2+m)]^3, where P1N2 is tissue PN2 before decompression, P2 is barometric pressure at altitude, and m is the threshold parameter. Also, the washout halftime of the relevant tissue is much longer than anticipated. CONCLUSIONS: Whether or not the mechanistic interpretations are valid, the models are useful predictors of DCS.
Description: Abstract of the Undersea and Hyperbaric Medical Society, Inc. Annual Scientific Meeting held July 7-10, 1993. World Trade and Convention Centre, Halifax, Nova Scotia, Canada. (http://www.uhms.org)
URI: http://archive.rubicon-foundation.org/8166
Date: 1993

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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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