[abstract] EFFECT OF CO2 ON HYPOXIC VENTILATORY RESPONSE IN HUMANS

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[abstract] EFFECT OF CO2 ON HYPOXIC VENTILATORY RESPONSE IN HUMANS

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Title: [abstract] EFFECT OF CO2 ON HYPOXIC VENTILATORY RESPONSE IN HUMANS
Author: Fabling, JM; Borel, CO; Guy, J; Natoli, MJ; Vann, RD
Abstract: BACKGROUND: Ventilatory response to acute hypobaric hypoxia is blunted by alkalosis and hypocarbia. Whilst CO2-supplemented breathing has been shown to limit inhibition of ventilation under these conditions, the effect on alveolar and arterial oxygenation has not been specifically examined in humans at altitude. METHODS: With IRB approval and informed consent, 4 male and 3 female subjects were randomly exposed to PB 430 mmHg at FIO2 21percent with or without FICO2 3.7percent. Subjects and investigators were blinded to condition. Measurements of Vt, Vf, PAW, SpO2, arterial, inspired, and expired gases were made at sea-level then at altitude after 4, 8 and 12 hours. During each 30-minute recording period, subjects breathed spontaneously through a low resistance circuit. Data were analyzed by repeated measures ANOVA and 12 hour means reported +/- SE, significance at p less than 0.05(). RESULTS: With CO2-supplemented breathing, there were significant increases in Ve, Vf, PAO2, PaO2 and SpO2 compared to control condition; and significant reductions in pH (7.43 +/- .002 vs. 7.48 +/- .004) and (A-a)O2. There were no differences between groups in Vt or Vd/Vt. Significant effects over 12h were: SpO2 declined in the control group; Vd/Vt decreased in both groups (0.33 +/- 0.01 to 0.28 +/- 0.01). :Vf:Ve:PaO2:(A-a)O2:SpO2:PaCO2 :::(mmHg)::(percent):(mmHg) Air:13 +/- 1:12.7 +/- 0.5:39.8 +/- 1.5:5.02 +/- 0.6:75 +/- 2.3:29.8 +/- 0.7 CO2:16.3 +/- 0.8:15.6 +/- 0.8:55.9 +/- 0.7:-0.62 +/- 0.72:90.8 +/- 0.5:36.5 +/- 0.5 CONCLUSION: These results suggest that CO2 supplementation improves arterial oxygenation during hypobaric hypoxia by increasing Ve and decreasing shunt fraction.
Description: Undersea and Hyperbaric Medical Society, Inc. (http://www.uhms.org )
URI: http://archive.rubicon-foundation.org/415
Date: 1997

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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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