Am. J. Respir. Crit. Care Med., Vol 152, No. 6, Dec 1995, 1812-1817.
Thermodilution cardiac output may be incorrect in patients on venovenous extracorporeal lung assist
M Haller, C Zollner, W Manert, J Briegel, E Kilger, J Polasek, T Hummel, H Forst and K Peter
Department of Anesthesiology, Ludwig-Maximilians-University of Munich, Germany.
Cardiac output measurement is part of routine monitoring in critically ill
patients. In patients on extracorporeal lung assist, thermodilution cardiac
output measurement may lead to erroneous results caused by indicator loss
into the extracorporeal circuit. Seven patients on venovenous
extracorporeal lung assist were studied using different extracorporeal
blood flows. We compared conventional thermodilution cardiac output
determinations with dye dilution cardiac output measurement, with dye
injection into the pulmonary artery. The latter method is not affected by
the extracorporeal circuit. The conventional thermodilution method
overestimated cardiac output up to a maximum of 300%, providing results up
to 10 L/min higher than true cardiac output. The mean difference between
thermodilution and true cardiac output as determined by dye dilution with
pulmonary artery indicator injection was 3.0 +/- 2.41 L/min. There was no
correlation between thermodilution cardiac output values and true cardiac
output (r = 0.06). We conclude that conventional thermodilution is not a
suitable method for cardiac output measurement in patients on
extracorporeal lung assist, especially if high extracorporeal blood flows
are applied.
