Comparison of the Pulse Wave Transit Time Method and an Arterial Pressure-Based Cardiac Output System for Measuring Cardiac Output Trends During Laparotomy Without Postural Change

Objective: Perioperative intravascular volume can be optimised by identifying predictors of fluid responsiveness. This study compared the estimated continuous cardiac output (esCCO) system for non- invasive measurement and an arterial pressure-based cardiac output (APCO) system for detecting exact changes in cardiac output (CO) among patients undergoing laparotomy without postural change. Methods: This study was performed at Toho University Omori Medical Centre in Japan from April 2016 to July 2016 and included 26 adult patients undergoing elective laparotomy lasting > 2 h without postural change. We evaluated both interchangeability and dynamic trend. After entering the biometric data (age, sex, height, weight, heart rate, pulse wave transit time, and blood pressure), the esCCO device was calibrated. All patients were also monitored with the APCO system. Data were analysed and compared for 12 adult patients using Bland­Altman analysis and polar plots. Results: The CO value obtained with esCCO was 0.75 ± 0.86 L/min (percentage error: 41%) lower than that obtained with the APCO system. Polar plotting revealed that the mean angular bias was 3.5°, and the radial limit of agreement was 28.3°. Conclusion: This study demonstrated that data obtained using esCCO are not interchangeable with those obtained using the APCO system. The trending ability of the esCCO device was deemed good among patients undergoing laparotomy without postural change.

Comparison of the ability of two continuous cardiac output monitors to measure trends in cardiac output: estimated continuous cardiac output measured by modified pulse wave transit time and an arterial pulse contour-based cardiac output device.

Estimated continuous cardiac output (esCCO), a noninvasive technique for continuously measuring cardiac output (CO), is based on modified pulse wave transit time, which in turn is determined by pulse oximetry and electrocardiography. However, its trending ability has never been evaluated in patients undergoing non-cardiac surgery. Therefore, this study examined esCCO's ability to detect the exact changes in CO, compared with currently available arterial waveform analysis methods, in patients undergoing kidney transplantation. CO was measured using an esCCO system and arterial pressure-based CO (APCO), and compared with a corresponding intermittent bolus thermodilution CO (ICO) method. Percentage error and statistical methods, including concordance analysis and polar plot analysis, were used to analyze results from 15 adult patients. The difference in the CO values between esCCO and ICO was -0.39 ± 1.15 L min(-1) (percentage error, 35.6 %). And corrected precision for repeated measures was 1.16 L min(-1) (percentage error for repeated measures, 36.0 %). A concordance analysis showed that the concordance rate was 93.1 %. The mean angular bias was -1.8° and the radial limits of agreement were ±37.6°. The difference between the APCO and ICO CO values was 0.04 ± 1.37 L min(-1) (percentage error, 42.4 %). And corrected precision for repeated measures was 1.37 L min(-1) (percentage error for repeated measures, 42.5 %). The concordance rate was 89.7 %, with a mean angular bias of -3.3° and radial limits of agreement of ±42.2°. This study demonstrated that the trending ability of the esCCO system is not clinically acceptable, as judged by polar plots analysis; however, its trending ability is clinically acceptable based on a concordance analysis, and is comparable with currently available arterial waveform analysis methods.