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Field validation of Tasmania's aquaculture industry bounce-diving schedules using Doppler analysis of decompression stress

Citation

Smart, DR and Van den Broek, C and Nishi, R and Cooper, PD and Eastman, D, Field validation of Tasmania's aquaculture industry bounce-diving schedules using Doppler analysis of decompression stress, Diving and Hyperbaric Medicine, 44, (3) pp. 124-136. ISSN 1833-3516 (2014) [Refereed Article]


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Copyright 2014 The Authors

Official URL: http://www.dhmjournal.com/files/Smart_-_Field_vali...

Abstract

Introduction: Tasmania's aquaculture industry produces over 40,000 tonnes of fish annually, valued at over AUD500M. Aquaculture divers perform repetitive, short-duration bounce dives in fish pens to depths up to 21 metres' sea water (msw). Past high levels of decompression illness (DCI) may have resulted from these 'yo-yo' dives. This study aimed to assess working divers, using Doppler ultrasonic bubble detection, to determine if yo-yo diving was a risk factor for DCI, determine dive profiles with acceptable risk and investigate productivity improvement.

Methods: Field data were collected from working divers during bounce diving at marine farms near Hobart, Australia. Ascent rates were less than 18 m·min⁻¹, with routine safety stops (3 min at 3 msw) during the final ascent. The Kisman-Masurel method was used to grade bubbling post dive as a means of assessing decompression stress. In accordance with Defence Research and Development Canada Toronto practice, dives were rejected as excessive risk if more than 50% of scores were over Grade 2.

Results: From 2002 to 2008, Doppler data were collected from 150 bounce-dive series (55 divers, 1,110 bounces). Three series of bounce profiles, characterized by in-water times, were validated: 13-15 msw, 10 bounces inside 75 min; 16-18 msw, six bounces inside 50 min; and 19-21 msw, four bounces inside 35 min. All had median bubble grades of 0. Further evaluation validated two successive series of bounces. Bubble grades were consistent with low-stress dive profiles. Bubble grades did not correlate with the number of bounces, but did correlate with ascent rate and in-water time.

Conclusions: These data suggest bounce diving was not a major factor causing DCI in Tasmanian aquaculture divers. Analysis of field data has improved industry productivity by increasing the permissible number of bounces, compared to earlier empirically-derived tables, without compromising safety. The recommended Tasmanian Bounce Diving Tables provide guidance for bounce diving to a depth of 21 msw, and two successive bounce dive series in a day's diving.

Item Details

Item Type:Refereed Article
Keywords:decompression sickness, decompression tables, diving research, diving tables, Doppler, Occupational diving, repetitive diving, surface supply breathing apparatus (SSBA)
Research Division:Medical and Health Sciences
Research Group:Clinical Sciences
Research Field:Clinical Sciences not elsewhere classified
Objective Division:Health
Objective Group:Clinical Health (Organs, Diseases and Abnormal Conditions)
Objective Field:Clinical Health (Organs, Diseases and Abnormal Conditions) not elsewhere classified
UTAS Author:Smart, DR (Associate Professor David Smart)
ID Code:100407
Year Published:2014
Deposited By:Medicine
Deposited On:2015-05-14
Last Modified:2017-11-03
Downloads:180 View Download Statistics

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