Purpose: The aim of this study was to assess the accuracy of the first and third versions of arterial pressure waveform cardiac output (APCO(v.1.0) and APCO(v.3.0)) measurements in comparison with thermodilution methods in patients undergoing living donor liver transplantation.
Methods: Twenty patients were anesthetized and mechanically ventilated. A radial arterial line was connected to a dedicated transducer for the APCO evaluation (FloTrac™). A pulmonary artery catheter was placed and connected to a computer system (Vigilance™) to measure intermittent thermodilution cardiac output (CO(TD)) and continuous cardiac output (CCO).
Results: A total of 138 measurements were analyzed. Bland-Altman analysis showed that the mean biases for CO(TD)-APCO(v.3.0), CO(TD)-APCO(v.1.0), and CO(TD)-CCO were 0.89, 1.73, and -0.79 L/min, and the adjusted percentage errors were 37.5, 30.3, and 43%, respectively. While the variance for CO(TD)-APCO(v3.0) was greater, the accuracy (bias) improved by 0.8 L/min as compared with CO(TD)-APCO(v1.0). The difference CO(TD)-APCO(v.3.0) became apparent when systemic vascular resistance was lower than 1000 dyne × s/cm(5), especially below 700 dyne × s/cm(5).
Conclusion: These data suggest that the accuracy of APCO(v.3.0) has improved compared to APCO(v.1.0) due to the updated algorithm, but additional improvements should be evaluated, especially in patients undergoing living donor liver transplantation with low systemic vascular resistance.