[abstract] WHOLE BODY NITROGEN ELIMINATION DURING INHALATION OF CO2 ENRICHED GAS MIXTURES.

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[abstract] WHOLE BODY NITROGEN ELIMINATION DURING INHALATION OF CO2 ENRICHED GAS MIXTURES.

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Title: [abstract] WHOLE BODY NITROGEN ELIMINATION DURING INHALATION OF CO2 ENRICHED GAS MIXTURES.
Author: Anderson, DE; George, L; Lundgren, CEG
Abstract: The rate of inert gas uptake and elimination is greatly dependent on tissue blood perfusion (e.g. 1,2). This dependence may translate into an altered risk of decompression sickness if perfusion is modified during periods of inert gas exchange preceding or coinciding with decompression (3). Given the possibility that CO2 may modify cardiovascular function, this study was performed to record possible changes in nitrogen elimination and blood circulation during breathing of normoxic argon mixtures containing 0, 3 and 5% CO2, These CO2 concentrations were chosen because they were subjectively tolerable in 2 hour exposures. They also would be comparable to CO2 loads that may be encountered due to malfunctioning or inadequately designed diving gear. Six volunteer subjects breathed the gas mixtures on a closed circuit system for measurement of exhaled nitrogen volume by gasometer and gas chromatograph. Nitrogen diffusion through the skin as a source of error was minimized by surrounding the subject with oxygen. Cardiac output (impedance cardiography) was also recorded. The average pre-experimental cardiac output of 8.33 .± 0.18 (SE) L/min gradually feU off by about 10% during the washout, apparently as a resting effect. In addition, the cardiac output showed a slight tendency to be higher (by 2-5%) throughout the 2 hr washout period with the 5% CO2 gas mixture than with the 3% and 0% mixtures, but this difference did not reach statistical significance. The cumulative nitrogen elimination at the end of the wash-out period averaged 814.± 23 (SE) ml STPD with 0% CO2 in the inhaled gas, 839 .± 17 (SE) ml with the 3% and 844 .± 26 (SE) mt with the 5% CO2 mixture. These nitrogen yields were not significantly different although the tendency for increased rates of nitrogen elimination during CO2 inhalation were visible already after 15 min of washout. We conclude that, to the extent that whole-body nitrogen load is of consequence for decompression stress, inhalation of up to 5% carbon dioxide (in normoxic gas mixtures) at one atmosphere during nitrogen washout is not likely to substantially modify decompression risk. References: (1) Balldin, UJ and CEG Lundgren. Aerospace Med 43:1101-1108, 1972. (2) Anderson, DE, GK Nagasawa, CEG Lundgren and AJ Olszowka. Undersea Biomed Res 15:83(Suppl), 1988. (3) Balldin, UJ. Forsvarsmedicin (Stockholm) 9:1973. This work was supported by New York Sea Grant Institute, NA86AADSG045.
Description: Abstract of the Undersea and Hyperbaric Medical Society, Inc. Joint Annual Scientific Meeting with the International Congress for Hyperbaric Medicine and the European Undersea Biomedical Society held 11-18 August 1990. Okura Hotel, Amsterdam, The Netherlands (http://www.uhms.org)
URI: http://archive.rubicon-foundation.org/7144
Date: 1990

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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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