Journal of Applied Physiology, Vol 67, Issue 4 1551-1559, Copyright © 1989 by American Physiological Society

ARTICLES

Decreased O2 consumption and cardiac output during normobaric hyperoxia in conscious dogs

R. F. Lodato
Department of Internal Medicine, University of Texas Health Science Center Houston 77030.

Recent reports indicate that under certain restricted conditions hyperoxia may decrease tissue O2 consumption. However, this effect has not been established for whole body O2 consumption in the intact healthy conscious state. The goal of the present study was to document the effect of hyperoxia on resting whole body O2 consumption and hemodynamics under these latter more general physiological conditions. The inspired gas was delivered by mask to six fasted resting conscious dogs and alternated hourly between air and O2-enriched air (hyperoxia) for 5 h, while hemodynamics and blood gas data were obtained every 20 min. Compared with air breathing, hyperoxia increased the mean arterial O2 tension from 95 to 475 Torr and decreased heart rate, cardiac output, pulmonary vascular resistance, and right and left ventricular work rates and thus, presumably, myocardial O2 consumption. Hyperoxia also increased systemic vascular resistance and right atrial pressure but did not change stroke volume or systemic arterial pressure. The increase in arterial O2 content during hyperoxia was counterbalanced by the decrease in cardiac output, so that O2 delivery was unchanged by hyperoxia. Surprisingly, hyperoxia decreased the arterial-to-mixed venous difference in O2 content; this decrease together with the decrease in cardiac output produced a decrease in resting whole body O2 consumption from 5.88 +/- 0.68 to 4.80 +/- 0.62 ml O2.min-1.kg-1 (P = 0.0002). It is concluded that under physiological conditions normobaric hyperoxia may decrease metabolic rate in addition to cardiac output, which may have important implications for the metabolic regulation of O2 utilization as well as for the medical and nonmedical uses of O2.

This article has been cited by other articles:

				D. A. Vagts, K. Hecker, T. Iber, J. P. Roesner, A. Spee, B. Otto, R. Rossaint, and G. F. E. Noldge-Schomburg Effects of xenon anaesthesia on intestinal oxygenation in acutely instrumented pigs Br. J. Anaesth., December 1, 2004; 93(6): 833 - 841. [Abstract] [Full Text] [PDF]

				K. S. Bandali, M. P. Belanger, and C. Wittnich Hyperoxia causes oxygen free radical-mediated membrane injury and alters myocardial function and hemodynamics in the newborn Am J Physiol Heart Circ Physiol, August 1, 2004; 287(2): H553 - H559. [Abstract] [Full Text] [PDF]

				A. G. Tsai, P. Cabrales, R. M. Winslow, and M. Intaglietta Microvascular oxygen distribution in awake hamster window chamber model during hyperoxia Am J Physiol Heart Circ Physiol, October 1, 2003; 285(4): H1537 - H1545. [Abstract] [Full Text] [PDF]

				E. N. Bruce and M. C. Bruce A multicompartment model of carboxyhemoglobin and carboxymyoglobin responses to inhalation of carbon monoxide J Appl Physiol, September 1, 2003; 95(3): 1235 - 1247. [Abstract] [Full Text] [PDF]

				L. Belhassen, G. Pelle, S. Sediame, D. Bachir, C. Carville, C. Bucherer, C. Lacombe, F. Galacteros, and S. Adnot Endothelial dysfunction in patients with sickle cell disease is related to selective impairment of shear stress-mediated vasodilation Blood, March 15, 2001; 97(6): 1584 - 1589. [Abstract] [Full Text] [PDF]

				O. D. Saugstad, T. Rootwelt, and O. Aalen Resuscitation of Asphyxiated Newborn Infants With Room Air or Oxygen: An International Controlled Trial: The Resair 2 Study Pediatrics, July 1, 1998; 102(1): 1e - 1. [Abstract] [Full Text]