Are noninvasive continuous cardiac output monitoring interchangeable with esophageal doppler?

Objective: To compare the trending ability, accuracy, and precision of non-invasive stroke volume (SV) measurement based on a bioreactance technique and measurement of the pulse wave transit time (PWTT) versus the esophageal Doppler monitoring (EDM). Materials and Methods: Two hundred twenty-seven paired measurements from 10 patients who underwent abdominal surgery under general anesthesia were included for SV measurements. Pearson's correlation coefficient was calculated, and Bland-Altman analysis was performed to evaluate the agreement between EDM and bioreactance (EDM-bioreactance) and between EDM and PWTT (EDM-PWTT). Results: EDM-bioreactance had a correlation coefficient of 0.75 (95% confidence interval [CI] 0.62 to 0.78; p<0.001), bias of 0.28 ml (limits of agreement -30.92 to 31.38 ml), and percentage error of 46.82%. EDM-PWTT had a correlation coefficient of 0.48 (95% CI 0.44 to 0.72; p<0.001), bias of -0.18 ml (limits of agreement -40.28 to 39.92 ml), and percentage error of 60.17%. A subgroup analysis of data from patients who underwent crystalloid loading was performed to detect the trending ability. The four-quadrant plot analysis between EDM-bioreactance and EDM-PWTT demonstrated concordance rates of 70.00% and 73.68%, respectively. Conclusion: SV measurement based on bioreactance technique and measurement of PWTT are not interchangeable with EDM.