Evaluation of cardiac output by bioreactance technique in patients undergoing liver transplantation

Background

This study compared the cardiac output (CO) obtained from PiCCO with that obtained from the noninvasive NICOM method.

Methods

Twenty-one cirrhotic patients receiving liver transplantation were enrolled. During the operation, their CO was measured by the PiCCO system via the thermodilution method as the standard and by the NICOM method. Two parameters including cardiac index (CI) and stroke volume index (SVI) were collected simultaneously at three phases during the surgery including the dissection phase (T1), the anhepatic phase (T2), and the reperfusion phase (T3). Correlation, Bland and Altman methods, and linear mixed model were used to evaluate the monitoring ability of both systems.

Results

Poor correlation was noted between the data measured by NICOM and PiCCO; the correlation coefficients for CI and SVI measured between the two systems were 0.32 and 0.39, respectively. Bland and Altman analysis showed the percentage error of CI as 63.7%, and that of SVI as 66.6% for NICOM compared to PiCCO. Using the linear mixed model, the CI and SVI measured using NICOM were significantly higher than those using PiCCO (estimated regression coefficient 0.92 and 10.77, both p < 0.001). Mixed model analysis showed no differences between the trends of CI and SVI measured by the two methods.

Conclusions

NICOM provided a comparable CI and SVI trend when compared to the gold standard PiCCO, but it raises concerns as an effective CO monitor because of its tendency to overestimate CI and SVI especially during the state of high cardiac output.