Cardiac output measurement in patients undergoing liver transplantation: pulmonary artery catheter versus uncalibrated arterial pressure waveform analysis.

BACKGROUND

Cardiac output (CO) and invasive hemodynamic measurements are useful during liver transplantation. The pulmonary artery catheter (PAC) is commonly used for these patients, despite the potential complications. Recently, a less invasive device (Vigileo/FloTrac) became available, which estimates CO using arterial pressure waveform analysis without external calibration. In this study, we compared CO obtained with a PAC using automatic thermodilution, instantaneous CO stat-mode (ICO(SM)), and CO obtained with the new device, arterial pressure waveform analysis (APCO) in patients undergoing liver transplantation.

METHODS

Twenty sets of simultaneous measurements of APCO and ICO(SM) were determined in sedated and mechanically ventilated patients undergoing liver transplantation. Time points were as follows: after PAC insertion (T1-3), after portal clamping (T4-6), during anhepathy (T7-9), after graft reperfusion (T10-15), and in the postoperative period in the intensive care unit (T15-20).

RESULTS

We enrolled 20 patients and 400 measurements were obtained. No data were rejected. Bias between ICO(SM) and APCO was 0.8 L/min, 95% limits of agreement were -1.8 to 3.5 L/min. The percentage error was 43%. Bias between ICO(SM) and APCO was correlated with systemic vascular resistance [r(2) = 0.55, P < 0.0001, y = 15.8-2.2 ln(x)] and subgroup analysis revealed an increase in the bias and in the percentage error in patients with low systemic vascular resistance (Child-Pugh grade B and C patients). There was no difference between the different surgical periods.

CONCLUSIONS

Our results suggest that Vigileo/FloTrac CO monitoring data do not agree well with those of automatic thermodilution in patients undergoing liver transplantation, especially in Child-Pugh grade B and C patients with low systemic vascular resistance.