Impedance cardiography: can it replace thermodilution and the pulmonary artery catheter?

Clinical assessment of cardiac output (CO) is inaccurate, yet the use of the pulmonary artery catheter (PAC) for thermodilution (TD) measurement of CO (CO(TD)) has declined significantly. Can noninvasive impedance cardiography (ICG) now be used to measure CO (CO(ICG)) in place of CO(TD)? A literature review of recent CO(ICG) correlations with CO(TD) (r = 0.73-0.92) were similar to ours, r = 0.81. A search for conditions interfering with CO(ICG) revealed no serious problems with patient position, cardiac or pulmonary assist devices, "wet lungs," body mass index > or = 30, or age > or = 70 years. A prospective randomized study was initiated beginning with a record of physician assessment of CO as high, normal, or low; concordance was 57%. Data from ICG was revealed only in the study group, resulting in a 49 per cent change in treatment compared with 29 per cent in the control group. Length of stay was shorter in the study than the control group in the intensive care unit (2.4 +/- 8.8 vs 3.3 +/- 7.3 days) and on the floor (9.8 +/- 10.6 vs 15.7 +/- 19.0 days). In conclusion, ICG is comparable with TD, is easily, accurately, and safely performed, enhances clinical assessment of CO, and improves care in hemodynamically compromised patients.