[abstract] A PROBABILISTIC GAS AND BUBBLE DYNAMICS MODEL PROVIDES IMPROVED ESTIMATES OF DCS RISK DURING OXYGEN DECOMPRESSION FROM AIR DIVES

Rubicon Research Repository/Manakin Repository

[abstract] A PROBABILISTIC GAS AND BUBBLE DYNAMICS MODEL PROVIDES IMPROVED ESTIMATES OF DCS RISK DURING OXYGEN DECOMPRESSION FROM AIR DIVES

Show full item record


Title: [abstract] A PROBABILISTIC GAS AND BUBBLE DYNAMICS MODEL PROVIDES IMPROVED ESTIMATES OF DCS RISK DURING OXYGEN DECOMPRESSION FROM AIR DIVES
Author: Gerth, WA; Vann, RD
Abstract: BACKGROUND: A probabilistic model in which DCS risk is a function of modeled bubble volumes in three parallel-perfused gas exchange compartments [BVM(3)] has been shown to correlate and perform about the data used to parameterize the U.S. Navy Air/N2-O2 Algorithm (USN93) as well as USN93. However, the performance of BVM3 about dives in which 100percent oxygen is breathed during decompression, where USN93 has been shown to under-estimate DCS risk, has not been examined. METHODS: Data from a chamber dive trial at the Naval Medical Research Institute (NMR94EOD) reported by Survanshi, et al. [Undersea and Hyperbaric Med 22(S):66, 1995] and an unpublished series of 130 fsw air dives at Duke University (MOONVQ) were analyzed using BVM(3) and our independent implementation of USN93 [USN93(D)]. Dives used decompressions consisting of periods of 100percent oxygen breathing (25 min O2 followed by 5 min air) commencing on arrival at the 60, 50 or 40 fsw stop. RESULTS: BVM(3) underestimated observed DCS incidence in each of the dive series less severely than USN93(D) [Table 1] and, excepting the 60/180 schedule, prescribed total oxygen decompression times (TDT @ 5percent limiting PDCS) for specific depth/bottom time combinations close to those accepted in the NMRI trial (PDCS less than 5percent @ 90percent confidence) [Table 2]. Table 1 Table 2 :::--------- number DCS ---------:Profile:Accepted:Prescribed: Data Set:Profiles:Exposures:Observed:Predicted:Fsw/min:TDT, mon:TDT, min: ::::USN93(D):BVM(3):::USN93(D):BVM(3) NMR94EOD:7:284:17.3:8.1:13.4:60/180:21:22:13 MOONVQ:5:69:3.3:0.2:1.2:60/240:61:64:58 Totals:12:353:20.6:8.3:14.6:150/55:85:39:82 ::::::170/40:58:26:67 Marginal DCS counted as 0.1 incident CONCLUSION: Severance of the direct link between compartmental gas supersaturation and DCS risk that is characteristic of USN93 and insertion of intervening processes modeled as bubble growth and resolution allows BVM(3) to provide improved prescriptions for oxygen decompressions from air dives without empirical adjustments required by USN93. (Supported by NOAA-NURP, USSOC and DAN).
Description: Undersea and Hyperbaric Medical Society, Inc. (http://www.uhms.org )
URI: http://archive.rubicon-foundation.org/370
Date: 1997

Files in this item

Files Size Format View
abstract.txt 259bytes 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