Comparing the Mutual Interchangeability of ECOM®, FloTrac®/Vigileo, 3D-TEE and ITD-PAC Cardiac Output Measuring Systems in Coronary Artery Bypass Grafting

Abstract Objective The aim of this study was to compare the mutual interchangeability of four cardiac output measuring devices by comparing their accuracy, precision and trending ability. Design A single-center prospective observational study. Setting Non–university teaching hospital, single center. Participants 44 consecutive patients scheduled for elective, non-emergent coronary artery bypass grafting (CABG). Interventions The cardiac output was measured for each participant using four methods: intermittent thermodilution via pulmonary artery catheter (ITD-PAC), Endotracheal Cardiac Output Monitor (ECOM), FloTrac/Vigileo System (FLOTRAC), and Three-Dimensional Transesophageal Echocardiography (3D-TEE). Measurements and Main Results Measurements were performed simultaneously at 5 time points: pre-sternotomy, post-sternotomy, prior to cardiopulmonary bypass, after cardiopulmonary bypass, and after sternal closure. A series of statistical and comparison analyses including ANOVA, Pearson's correlation, Bland-Altman plots, Quadrant plots, and Polar plots were performed and inherent precision for each method and percent errors for mutual interchangeability were calculated. For the six two-by-two comparisons of the methods the Pearson correlation coefficients(r), the percentage errors (%error) and concordance ratios (CR) were as follows: ECOM_vs_ITD-PAC (r=0.611, %error=53%, CR=75%); FLOTRAC_vs_ITD-PAC (r=0.676, %error=49%, CR=77%); 3D-TEEvsITD-PAC (r=0.538, %error=64%, CR=67%); FLOTRAC_vs_ECOM (r=0.627, %error=51%, CR=75%); 3D-TEE_vs_ECOM (r=0.423, %error=70%, CR=60%) and 3D-TEE_vs_FLOTRAC (r=0.602, %error=59%, CR=61%). Conclusions: Based on the recommended statistical measures of interchangeability, ECOM, FLOTRAC, and 3D-TEE are not interchangeable with each other or to the reference standard invasive ITD-PAC method in patients undergoing non-emergent cardiac bypass surgery. Despite the negative result in this study and the majority of previous studies, these less-invasive methods of CO have continued to be used in the hemodynamic management of patients. Each device has its own distinct technical features and inherent limitations; it is clear that no single device can be used universally for all patients. Therefore, different methods or devices should be chosen based on individual patient conditions including the degree of invasiveness, measurement performance, and the ability to provide real-time, continuous CO readings.