Details

Autor(en) / Beteiligte

• Cherry, A. D
• Forkner, I. F
• Frederick, H. J
• Natoli, M. J
• Schinazi, E. A
• Longphre, J. P
• Conard, J. L
• White, W. D
• Freiberger, J. J
• Stolp, B. W
• Pollock, N. W
• Doar, P. O
• Boso, A. E
• Alford, E. L
• Walker, A. J
• Ma, A. C
• Rhodes, M. A
• Moon, R. E

Titel

Predictors of increased PaCO2 during immersed prone exercise at 4.7 ATA

Ist Teil von

• Journal of applied physiology (1985), 2009-01, Vol.106 (1), p.316-325

Ort / Verlag

United States: Am Physiological Soc

Erscheinungsjahr

2009

Quelle

MEDLINE

Beschreibungen/Notizen

• Center for Hyperbaric Medicine and Environmental Physiology and Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina Submitted 18 August 2007 ; accepted in final form 10 September 2008 During diving, arterial P CO 2 (Pa CO 2 ) levels can increase and contribute to psychomotor impairment and unconsciousness. This study was designed to investigate the effects of the hypercapnic ventilatory response (HCVR), exercise, inspired P O 2 , and externally applied transrespiratory pressure (P tr ) on Pa CO 2 during immersed prone exercise in subjects breathing oxygen-nitrogen mixes at 4.7 ATA. Twenty-five subjects were studied at rest and during 6 min of exercise while dry and submersed at 1 ATA and during exercise submersed at 4.7 ATA. At 4.7 ATA, subsets of the 25 subjects (9–10 for each condition) exercised as P tr was varied between +10, 0, and –10 cmH 2 O; breathing gas P O 2 was 0.7, 1.0, and 1.3 ATA; and inspiratory and expiratory breathing resistances were varied using 14.9-, 11.6-, and 10.2-mm-diameter-aperture disks. During exercise, Pa CO 2 (Torr) increased from 31.5 ± 4.1 (mean ± SD for all subjects) dry to 34.2 ± 4.8 ( P = 0.02) submersed, to 46.1 ± 5.9 ( P < 0.001) at 4.7 ATA during air breathing and to 49.9 ± 5.4 ( P < 0.001 vs. 1 ATA) during breathing with high external resistance. There was no significant effect of inspired P O 2 or P tr on Pa CO 2 or minute ventilation ( E ). E (l/min) decreased from 89.2 ± 22.9 dry to 76.3 ± 20.5 ( P = 0.02) submersed, to 61.6 ± 13.9 ( P < 0.001) at 4.7 ATA during air breathing and to 49.2 ± 7.3 ( P < 0.001) during breathing with resistance. We conclude that the major contributors to increased Pa CO 2 during exercise at 4.7 ATA are increased depth and external respiratory resistance. HCVR and maximal O 2 consumption were also weakly predictive. The effects of P tr , inspired P O 2 , and O 2 consumption during short-term exercise were not significant. transrespiratory pressure; respiratory resistance; hyperoxia; carbon dioxide response; diving Address for reprint requests and other correspondence: R. E. Moon, Dept. of Anesthesiology, Box 3094, Duke Univ. Medical Center, Durham, NC 27710 (e-mail: moon0002{at}mc.duke.edu )