Diving physics

Abstract: THE underwater environment, with its rapidly changing ambient pressures, presents pathophysiologic challenges that may lead to a variety of unusual diseases for which rapid diagnosis and treatment are critical. In the United States there are more than 5 million people certified as recreational scuba divers — that is, divers who use a self-contained underwater breathing apparatus. Given the popularity of scuba diving the world over and the number of diving accidents,1 every physician should be aware of the specific hazards and medical conditions encountered underwater. The barometric pressure at sea level is 100 kPa (the equivalent of 1 atmosphere absolute, . . .

Abstract: The rapid growth in the number of people using self-contained underwater breathing apparatus (SCUBA) for recreation and the increase in associated casualties have placed greater importance on undersea medicine. The change in the ambient pressure underwater may cause physiologic alterations that may pose particularly challenging diagnostic and treatment-related dilemmas. The aim of this report is to provide a brief overview of the medical problems associated with underwater diving, for which rapid diagnosis and treatment may be critical.

Abstract: INTRODUCTION: This is the second report based on a survey of Divers Alert Network Asia-Pacific (DAN AP) members who dive with cardiovascular and respiratory conditions and diabetes. It examines the medical management of the divers' conditions, any diving modifications used to mitigate the risk and outcomes. METHODOLOGY: An online cross-sectional survey was sent to 833 divers who had declared a targeted medical condition when applying for DAN AP membership between July 2009 and August 2013. RESULTS: Two-hundred-and-sixty-eight respondents (32%) provided sufficient information on their conditions to be included in the analyses. These included ischaemic heart disease (31), arrhythmias (20), cardiac septal defects (31), other cardiac conditions (10), hypertension (127), diabetes (25), asthma (40) and pneumothorax (5). Forty-nine per cent had sought specialist diving medical advice about their condition and 23% reported modifying their diving practices to mitigate their risk. The cohort had completed 183,069 career dives, 57,822 of these since being diagnosed with their medical condition. There were 27 individuals who reported having decompression illness (25 of whom were subsequently diagnosed with a persistent foramen ovale), and two individuals who experienced an arrhythmia during diving. CONCLUSIONS: Some DAN AP members are diving with medical conditions which could potentially impact the safety of their diving. A minority modified their diving practices to mitigate the risk of their condition and approximately half sought specialist diving medical advice. The incidence of diving-related problems precipitated by known and managed pre-existing health conditions seems low but further studies of larger cohorts and incorporating fatality data would be necessary to confirm this. These results are limited by the 32% response rate and potential for bias towards selection of those most careful with their health.