[abstract] MECHANISMS OF HYPERCAPNIA DURING EXERCISE AT 40 MSW

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[abstract] MECHANISMS OF HYPERCAPNIA DURING EXERCISE AT 40 MSW

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Title: [abstract] MECHANISMS OF HYPERCAPNIA DURING EXERCISE AT 40 MSW
Author: Morgan, BE; Breinbauer, B; Stolp, BW; Simonds, D; Dear, GdeL; Castellano, JM; Moon, RE
Abstract: INTRODUCTION: Hypercapnia during diving has been attributed to hypoventilation, atltered VA/Q matching and impaired gas phase diffusion. This study was designed to determine the role of each factor during exercise breathing normoxic N2-O2 at 40 msw simulated depth. METHODS: After institutional approval and informed consent 10 healthy volunteers (F = 5, M = 5; mean age = 35.9 years; range = 20 - 47) were instrumented with EKG and arterial and pulmonary artery catheters. During upright exercise in the dry, at the surface, and 40 msw depth (360 and 720 kpomomin-1) measurements were obtained of VO2, VCO2, VD/VT (Enghoff-Bohr) and O2 and CO2 tensions in arterial and mixed venous blood. Inspired gas was N2-O2(P1O2 = 160 mmHg) during all conditions. The technique of multiple inert gases (Wagner PD, et al. J Appl Physiol 36:588, 1974) was used to calculate 50 compartment VA/Q distributions, from which we calculated dispersions of the ventilation and perfusion distributions (logSDV, logSDQ), shunt, dead space and predicted arterial PCO2 (PaCO2). Statistics were calculated using repeated measures ANOVA. An asterisk () indicates an effect of depth: P less than .05. RESULTS: LogSDQ, shunt and inert gas dead space were unaffect by depth. CONCLUSION: Hypercapnia during dry exercise at 40 msw simulated depth is attributable to both hypoventilation and VA/Q mismatch. The discrepancy between predicted and measured PaCO2 at depth also suggests impaired intra-alveolar CO2 diffusion. This study was supported by NOAA (Grant #NA88AA-D-UR004) and the Divers Alert Network.
Description: Undersea and Hyperbaric Medical Society, Inc. (http://www.uhms.org )
URI: http://archive.rubicon-foundation.org/562
Date: 1996

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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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