Comparison of cardiac output determined by bioimpedance, thermodilution, and the Fick method.
BACKGROUND
Cardiac output can be determined by using a variety of methods.


OBJECTIVE
To determine the precision and bias between 3 methods for determining cardiac output: bioimpedance, thermodilution, and the Fick method.


METHODS
Cardiac output was determined by using bioimpedance via neck and thorax patches and thermodilution via pulmonary artery catheter in 46 patients in the intensive care unit. A subset of 15 patients also had cardiac output determined by using the Fick method.


RESULTS
Mean (SD) cardiac output in all patients was 6.3 (2.2) L/min by thermodilution and 5.6 (2.0) L/min by bioimpedance. In the 15 patients in whom all 3 methods were used, mean cardiac output was 6.0 (1.7) L/min by thermodilution, 5.3 (1.7) L/min by bioimpedance, and 8.6 (4.5) L/min by the Fick method. Bias and precision (mean difference +/- 2 SDs) were 0.7 +/- 2.9 L/min between thermodilution and bioimpedance, 1.7 +/- 3.8 L/min between the Fick method and thermodilution, and 2.4 +/- 4.7 L/min between the Fick method and bioimpedance.


CONCLUSIONS
Bioimpedance, thermodilution, and Fick determinations of cardiac outputs are not interchangeable in a heterogeneous population of critically ill patients.
Engoren
Milo
M
Department of Anesthesiology, St. Vincent Mercy Medical Center, Toledo, OH, USA.
Barbee
Daniel
D
D000368:Aged; D002302:Cardiac Output / Q000502:physiology*; D002307:Cardiography, Impedance / Q000379:methods; D002407:Catheterization, Swan-Ganz / Q000379:methods; D005260:Female; D006334:Heart Function Tests / Q000379:methods*; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013815:Thermodilution / Q000379:methods