[abstract] ASCENT RATES IN RECREATIONAL SCUBA DIVES RECORDED IN PROJECT DIVE EXPLORATION

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[abstract] ASCENT RATES IN RECREATIONAL SCUBA DIVES RECORDED IN PROJECT DIVE EXPLORATION

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Title: [abstract] ASCENT RATES IN RECREATIONAL SCUBA DIVES RECORDED IN PROJECT DIVE EXPLORATION
Author: DeNoble, PJ; Bute, BP; Uguccioni, DM; Sitzes, CR; Vann, RD; Bennett, PB
Abstract: BACKGROUND: Rapid ascent after diving may be a risk factor for decompression illness (DCI). Animal studies suggest there are fewer venous gas emboli (VGE) for ascents at 30 fpm rather than 60 fpm, and "safety stops" appear to reduce VGE incidence in humans. In 1993, the US Navy changed the rate of ascent (ROA) for air diving from 60 to 30 fpm. Human studies suggest that slow ascent rates are protective against DCI, but animal studies indicate the effect may be complex and depth related. DAN is investigating recreational diving ascent rates as part of Project Dive Exploration, a multi-year program to collect recreational diving data. METHODS: 16 women (mean age 39 y, sd 13) and 31 men (mean age 36 y, sd 18) volunteered to contribute their depth-time profiles during 15 dive trips, principally on live-aboard dive boats. Maximum depths during 20 sec time intervals were recorded by dive computers. Dive profiles were analyzed for maximum depth, ascent rate in 20 fsw depth intervals, final ascent rate to the surface, and safety stops. RESULTS: 357 dives were recorded with no reported DCI. The most frequent maximum depth for this group of divers was 60-80 fsw. One-quarter to one-third of this population sample had ascent rates exceeding the recommended 30 fpm. Half the divers practiced a safety stop as defined as more than 3 min at 20 fsw or less. Max Depth # Depth Range ROA fpm #, greater than 120', 26, 100-120, 62, 80-0, 180, 4, 80-100, 58, 60-0, 120, 14, 60-80, 135, 40-0, 60, 58, 40-60, 54, Any 20', 60, 1, 20-40, 18, Interval, 30, 26 CONCLUSIONS: Dive computers with a recording interval of 20 sec can detect ascent rates in excess of 60 fpm but can miss rates of less then 60 fpm for ascents of less than 20 fsw. For accurate ascent rate measurement, a minimum recording interval of 5 sec is recommended. The effects of ascent rate on DCI risk may become apparent as more dives are collected, and some DCI cases occur.
Description: Undersea and Hyperbaric Medical Society, Inc. (http://www.uhms.org )
URI: http://archive.rubicon-foundation.org/662
Date: 1998

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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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