Cardiac output estimated noninvasively from oxygen uptake during exercise

• Published in: Journal of applied physiology (1985) Vol. 82; no. 3; pp. 908 - 912
• Main Authors: Stringer, William W, Hansen, James E, Wasserman, K
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.03.1997; American Physiological Society
• Subjects: Adult; Biological and medical sciences; Cardiac Output - physiology; Exercise - physiology; Fundamental and applied biological sciences. Psychology; Heart; Humans; Male; Oxygen - metabolism; Vertebrates: cardiovascular system; Heart; Physical exercise; Human; Blood gas; PaO2; Partial pressure; Bicycle ergometer; Oxygen consumption; Circulatory system; Hemodynamics; Blood flow; PvO2
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.1997.82.3.908

William W. Stringer, James E. Hansen, and K. Wasserman Division of Respiratory and Critical Care Physiology and Medicine, Harbor-UCLA Medical Center, Torrance, California 90509 Received 22 July 1996; accepted in final form 24 October 1996. Stringer, William W., James E. Hansen, and K. Wasserman. Cardiac output estimated noninvasively from oxygen uptake during exercise. J. Appl. Physiol. 82(3): 908-912, 1997. Because gas-exchange measurements during cardiopulmonary exercise testing allow noninvasive measurement of oxygen uptake ( O 2 ), which is equal to cardiac output (CO) × arteriovenous oxygen content difference [C(a-vD O 2 )], CO and stroke volume could theoretically be estimated if the C(a-vD O 2 ) increased in a predictable fashion as a function of %maximum O 2 ( O 2 max ) during exercise. To investigate the behavior of C(a-vD O 2 ) during progressively increasing ramp pattern cycle ergometry exercise, 5 healthy subjects performed 10 studies to exhaustion while arterial and mixed venous blood were sampled. Samples were analyzed for blood gases (pH, P CO 2 , P O 2 ) and oxyhemoglobin and hemoglobin concentration with a CO-oximeter. The C(a-vD O 2 ) (ml/100 ml) could be estimated with a linear regression [C(a-vD O 2 ) = 5.72 + 0.105 × % O 2 max ; r  = 0.94]. The CO estimated from the C(a-vD O 2 ) by using the above linear regression was well correlated with the CO determined by the direct Fick method ( r = 0.96). The coefficient of variation of the estimated CO was small (7-9%) between the lactic acidosis threshold and peak O 2 . The behavior of C(a-vD O 2 ), as related to peak O 2 , was similar regardless of cardiac function compared with similar measurements from studies in the literature performed in normal and congestive heart failure patients. In summary, CO and stroke volume can be estimated during progressive work rate exercise testing from measured O 2 (in normal subjects and patients with congestive heart failure), and the resultant linear regression equation provides a good estimate of C(a-vD O 2 ). ramp pattern cycle ergometer exercise; arterial oxygen content; mixed venous oxygen content; direct Fick cardiac output 0161-7567/97 $5.00 Copyright © 1997 the American Physiological Society