Comparison of two impedance cardiographic techniques for measuring cardiac output.

The purpose of the present study was to compare cardiac outputs obtained by both the Kubicek (MIC) and Sramek (NCCOM3) impedance cardiographic techniques with thermodilution (TD) in critically ill patients. The two impedance techniques were also compared in normal subjects. Seven healthy subjects and ten patients in the intensive care unit were enlisted in the study. Only those subjects with successful measurements by all three methods were used in the data analysis. Three measurements of cardiac output were made in each subject. In patients, there were no significant differences in cardiac outputs as measured by TD (6.61/min), MIC (6.3 1/min), NCCOM3 (6.4 1/min). MIC and NCCOM3 cardiac outputs were correlated and approximated the line of identify when compared to TD. In normals, however, the NCCOM3 overestimated the cardiac output (NCCOM3, 9.2 1/min; MIC, 6.2 1/min). Because of these inconsistent results, caution is urged when interpreting the values obtained by the NCCOM3. In contrast, the use of the MIC in both populations has been reaffirmed.