[abstract] HAEMATOCRIT CHANGE IN RECREATIONAL SCUBA DIVERS FOLLOWING SINGLE DIVE EXPOSURE

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[abstract] HAEMATOCRIT CHANGE IN RECREATIONAL SCUBA DIVERS FOLLOWING SINGLE DIVE EXPOSURE

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Title: [abstract] HAEMATOCRIT CHANGE IN RECREATIONAL SCUBA DIVERS FOLLOWING SINGLE DIVE EXPOSURE
Author: Williams, ST; Prior, F; Bryson, PJ
Abstract: BACKGROUND: Dehydration, for which haematocrit is a commonly quoted proxy measure, is a common contributor to decompression injuries in recreational scuba divers. Direct evidence for change in haematocrit in response to recreational air diving is scanty, being derived from related findings in saturation and breath-hold diving. This study investigates whether haematocrit change occurs in response to a single scuba dive in conditions typically encountered by recreational scuba divers. MATERIALS AND METHODS: 41 divers ( m=20, f=21 ) were recruited on a tropical reef survey site. Volunteers gave blood relating to a single air dive at mean 2.4 minutes before descent ( range 8 20, SD 3.5 minutes ) and 16.2 minutes after surfacing (range 9 25, SD 3.7 minutes ). Mean maximum dive depth was 13.6 metres ( range 7.4 18.1, SD 3.7 metres ). Water temperature was 30 Celsius with a range of 1 degree over the depths at which the divers operated. Samples were centrifuged on-site and haematocrit measured on a visual plate reader. RESULTS: Paired t-test showed overwhelming evidence (p less than 0.001) of a change in haematocrit, mean pre-dive Ht 0.4132 ( 95percent CI 0.4047 - 0.4217 ), mean post-dive Ht 0.4205 (95percent CI 0.4117 - 0.4294 ). Similarly significant results were found when the sexes were analysed individually. An unplanned finding, although not significant, suggests that despite a prolonged midday rest with rehydration, afternoon divers nonetheless started their dives in a less hydrated state than their morning colleagues. (mean pre-dive haematocrits 0.405 and 0.421 respectively for morning and afternoon divers, independent sample t-test p=0.54). CONCLUSIONS: This study finds a small but significant haemoconcentration associated with tropical recreational scuba diving. The timescale for correction of this change should be the subject of further work and may be of importance in the setting of repetitive same-day scuba diving.
Description: Undersea and Hyperbaric Medical Society, Inc. (http://www.uhms.org )
URI: http://archive.rubicon-foundation.org/1691
Date: 2005

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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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