Correlation of Cardiac Output Estimation by Analysis of Arterial Blood Pressure Waveforms versus Continuous Pulmonary Artery Thermodilution in Post Cardiac Surgery Intensive Care Unit Patients

Purpose: We sought to assess agreement of cardiac output estimation between continuous pulmonary artery catheter (PAC) guided thermodilution (CO-CTD) and a novel method that performs an analysis of multiple beats of the arterial blood pressure waveform (CO-MBA) in post-operative cardiac surgery patients. Methods PAC obtained CO-CTD measurements were compared with CO-MBA measurements from analysis of arterial blood pressure waveforms using the Argos monitor (Retia Medical; Valhalla, NY, USA), in prospectively enrolled adult cardiac surgical intensive care unit patients. Correlation between paired values of CO-CTD and CO-MBA was computed, and agreement was assessed via Bland-Altman analysis. Subgroup analysis was performed on data segments identified as arrhythmia. Results 927 hours of monitoring data from 79 patients was analyzed, of which 26 had arrhythmia. Mean CO-CTD was 5.29 ± 1.14 L/min (bias ± precision), whereas mean CO-MBA was 5.36 ± 1.33 L/min, (4.95 ± 0.80 L/min and 5.04 ± 1.07 L/min in the arrhythmia subgroup). Mean of differences was 0.04 ± 1.04 L/min, 95% limits of agreement: -2.00 to 2.08 L/min, and a percentage error of 38.2%. In the arrhythmia subgroup, mean of differences was 0.14 ± 0.90 L/min, 95% limits of agreement: -1.63 to 1.91 L/min and percentage error of 35.4%. Paired observations showed a moderate correlation throughout the cohort (r = 0.64). Conclusion CO measurements using a novel multi-beat analysis of the arterial pressure waveform are reasonably correlated with traditional more-invasive continuous PAC thermodilution guided cardiac output measurements in adult patients after cardiac surgery including in those with arrythmias.