[abstract] OXYGEN EFFECTS IN PROBABILISTIC MODELS OF DECOMPRESSION SICKNESS.

Rubicon Research Repository/Manakin Repository

[abstract] OXYGEN EFFECTS IN PROBABILISTIC MODELS OF DECOMPRESSION SICKNESS.

Show full item record


Title: [abstract] OXYGEN EFFECTS IN PROBABILISTIC MODELS OF DECOMPRESSION SICKNESS.
Author: Parker, EC; Survanshi, SS; Weathersby, PK; Thalmann, ED
Abstract: Probabilistic models of human decompression sickness (DCS), using several independent compartments with mixed Linear-Exponential kinetics, have been successful in describing the occurrence, and even the time of occurrence of DCS. However, these models have not done well in prediction of DCS occurrence in experimental dives which use a high fraction (~= 100%) of oxygen as the breathing gas during decompression. DCS occurrence in such dives is systematically under-predicted by about 60%. These models have ignored O2 and assumed that only N2 partial pressure contributes to the risk of DCS. Two new classes of models are explored in an attempt to identify a specific oxygen effect in the accumulation of decompression risk. The oxygen effects explored here are of two forms; the first has tissue inert gas time constants as a function of PO2, the second adds a fraction of the PO2 to the tissue supersaturation. The basic data set to which these models are fitted contains 3322 dives, of which 56% are air dives, with depths from 20 to 290 fsw (PO2 up to 2.1 ATA), and 44% are dives in which a constant PO2, usually 0.7 ATA, in N2 was the breathing gas. In addition, there are 729 dives available in which ~100% O2 was breathed either in decompression or during surface decompression procedures. The PO2 range for these dives is 1.3 to 2.8 ATA. The oxygen effect models are fitted to all available data. In the first class of PO2 effect models, two functions of inert gas kinetic dependence on PO2 are presented, allowing for a variety of responses. After an exhaustive search of parameters using the Maximum Likelihood method, no substantial PO2 effect of this type is supported by these data. The second class of model with a direct contribution of PO2 to risk accumulation results in a significant improvement in fit to the data, but no improvement is seen in the model's ability to predict DCS occurrence in the data. (Supported by NMRDC Work Unit No. 63713N M0099.01A-1002)
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/8161
Date: 1993

Files in this item

Files Size Format View
abstract.txt 258bytes Text file View/Open

This item appears in the following Collection(s)

  • UHMS Meeting Abstracts
    This is a collection of the published abstracts from the Undersea and Hyperbaric Medical Society (UHMS) annual meetings.

Show full item record

Browse

My Account