[abstract] A MATHEMATICAL MODEL OF BREATHOLD DIVING

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[abstract] A MATHEMATICAL MODEL OF BREATHOLD DIVING

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Title: [abstract] A MATHEMATICAL MODEL OF BREATHOLD DIVING
Author: Edge, CJ; Farmery, AD
Abstract: INTRODUCTION: Over the last few years, there has been an upsurge of interest in the sport of free-diving. Tragically, many cases of accidental drowning have been reported in divers competing to descend to greater depths. It has been suggested by Craig that hyperventilation by the diver reduces the carbon dioxide sensitivity to breathing, thus allowing the diver to become profoundly hypoxic, which results in unconsciousness. A mathematical model developed by Olszowka and Rahn showed that in addition to the hypoxia, reversal of oxygen transport during the last stages of ascent may occur. Some experimental support for this was provided by Lanphier and Rahn, and Hong. METHOD: Based on a mathematical model used to describe the rate of oxyhaemoglobin desaturation during apnoea, we have started to develop a new model of apnoea in the breath-hold diver. The model uses the equation: (1) where tc is the circulation time, Ca(t) is the arterial blood oxygen content, VO2 is the oxygen consumption rate in the tissues, VA is the alveolar volume, QT is the blood volume, FA is the fractional concentration of oxygen in alveolar gas, and denotes differentiation of term x with respect to time, together with the equation: where Cc is pulmonary capillary oxygen content and fs is the pulmonary shunt fraction. RESULTS: We have used Matlab (Matlab 6.1, The Mathworks Inc.) to model the oxygen saturation in arterial, pulmonary capillary and mixed venous blood. The graph of oxygen saturation of arterial, capillary and mixed venous blood during a dive to 100 msw is presented graphically. Parameters used were: alveolar volume 2.5 litres, blood volume 5 litres, cardiac output 5 litres/min, shunt fraction 0.05, oxygen uptake 250 ml/min, haemoglobin 15 g/dl, initial alveolar oxygen fraction 0.133, initial alveolar carbon dioxide fraction 0.0526.
Description: Undersea and Hyperbaric Medical Society, Inc. (http://www.uhms.org )
URI: http://archive.rubicon-foundation.org/1610
Date: 2004

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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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