Non-invasive measurement of cardiac output during anaesthesia. An evaluation of the soluble gas uptake method
Heneghan, C.P.; Branthwaite, M.A.
British Journal of Anaesthesia 53(4): 351-355
1981
ISSN/ISBN: 0007-0912 PMID: 7225268 Document Number: 175467
A technique for measuring cardiac output which depends on the uptake of an inert soluble gas from the lungs was evaluated during anesthesia. A respiratory mass spectrometer was used to follow the concentrations of Ar and freon-22 during passive rebreathing in anesthetized patients before cardiopulmonary bypass. Values for cardiac output obtained with this technique are reproducible, but lower than those recorded using the direct Fick technique before and after the rebreathing maneuver. A reduction in cardiac output caused by vigorous rebreathing is the most likely explanation for the discrepancy and, although serial measurements of O2 consumption may permit application of a correction factor, a method of measurement which causes significant hemodynamic disturbance cannot be recommended for widespread use.