Metabolic production of carbon dioxide in simulated sea states: relevance for hyperbaric escape systems.
Hyperbaric Escape Systems (HES) are used when saturation diving bells have to be evacuated and divers transported to safety. The aim of the present investigation was to determine the levels of metabolic CO2 production expected from the occupants of an HES in different wave states, and from this, to recommend a reasonable and safe requirement for scrubbing CO2 within an HES. The CO2 production and heart rate of 20 male subjects representing saturation divers were collected while they were seated in an HES seat, fixed to an inflatable rescue vessel. The vessel was tethered in a wave pool and longitudinal (L), perpendicular (P), and calm (C) sea conditions were reproduced. Heart rate did not differ between conditions (P=0.33) the mean (SD) heart rates (b x min(-1)) were: C: 71 (8.5); L: 74 (9); P: 75 (9). Carbon dioxide production was significantly higher (P=0.005) with the boat orientated perpendicular to the waves compared to the calm condition. The mean (plus 99% confidence interval) carbon dioxide production for each of the conditions was C = 319mL x min(-1) + (41mL x min(-1)) = maximum of 360mL x min(-1); L=374mL x min(-1) + (46mL x min(-1)) = maximum of 420mL x min(-1); P = 409mL x min(-1) + (57mL x min(-1)) = maximum of 466mL x min(-1). It is therefore recommended that a 12 person HES should be capable of scrubbing at least 8,053L of carbon dioxide in 24 hours. Thus, the current requirement for 8,415L in 24h is reasonable.
Tipton
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Department of Sport & Exercise Science, Institute of Biomedical & Biomolecular Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth PO1 2DT.
Newton
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P
Reilly
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T
D000328:Adult; D002245:Carbon Dioxide / Q000378:metabolism*; D004242:Diving / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D009038:Motion; D012146:Rest / Q000502:physiology
D002245:Carbon Dioxide