[abstract] Risks of Decompression sickness (DCS) in 125,091 air or N2/O2 recreational dives

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[abstract] Risks of Decompression sickness (DCS) in 125,091 air or N2/O2 recreational dives

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Title: [abstract] Risks of Decompression sickness (DCS) in 125,091 air or N2/O2 recreational dives
Author: Dunford, RG; Vann, RD; Li, L; Forbes, R; Denoble, PJ; Gerth, WA; Marroni, A
Abstract: Introduction: DAN collects dive computer-recorded depth-time profiles to investigate DCS risk in open-water recreational diving. Methods: Under IRB approval, volunteer divers provided depth-time-gas profiles with dive, demographic and medical outcome data. DCS was defined as manifestations consistent with the Perceived Severity Index (PSI) within 48 hours of diving that resolved on recompression (ASEM 2009;81:3-7). Air or N2/O2 dive profiles from 1995-2008 were scrutinized and anomalies rejected. Dive severity was controlled by an estimated measure of stress (DiveStress) (UHM 1997;24:275-92). Risk factors were assessed by multiple logistic regression; contrasts with T-tests. Significance accepted at p less than 0.05. Results: 125,091 dives (86.5% on air) included 38 DCS cases (%DCS=0.03) and represented 17,605 dive series (mean 14 dives/series) by 10,832 divers (71.2% male) with mean depth(±SD)=69±29 fsw and mean time=46±15 minutes. Starting from 20fsw, %DCS rose by 0.02 for each 30 fsw, increase in maximum depth. N2/O2 dives were deeper than air dives (82±32 fsw versus 67±28) but %DCS did not differ (0.04 versus 0.03). DiveStress was associated with increasing %DCS (Odds Ratio [OR]=1.63 per 0.1 DiveStress unit); 95% CI=1.3-2.0) and accounted for the maximum depth effect. Compared with warm-water liveaboard dives (%DCS=0.004; 40.0% of total dives; depth=67±26 fsw), cold-water wreck dives (%DCS=0.166; 13.5% of total dives; depth=88±29 fsw) had an OR greater than 30 (95% CI=9.4- greater than 30) while dives under other conditions (%DCS=0.014; 46.2% of total; depth=64±29 fsw) approached significance versus warm-water liveaboard dives (p=0.08) with OR=4.0(95% CI=0.8-18.9). The 15% of highest DiveStress value dives accounted for 55% of all DCS cases. Diving experience, age, gender and body mass index were not associated with DCS. Conclusions: DiveStress and cold-water wreck dives were associated with elevated %DCS. Reducing Dive - Stress values might avert most DCS. The increase in %DCS with maximum depth could indicate that some decompression algorithms incompletely account for depth. Support: NAVSEA Contract #N61331-06-C-0014.
Description: Undersea and Hyperbaric Medicine : Journal of the Undersea and Hyperbaric Medical Society, Inc.
URI: http://archive.rubicon-foundation.org/9882
Date: 2011

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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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