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.