Accuracy of a noninvasive estimated continuous cardiac output measurement under different respiratory conditions: a prospective observational study.

PURPOSE: The estimated continuous cardiac output (esCCO) system was recently developed as a noninvasive hemodynamic monitoring alternative to the thermodilution cardiac output (TDCO). However, the accuracy of continuous cardiac output measurements by the esCCO system compared to TDCO under different respiratory conditions remains unclear. This prospective study aimed to assess the clinical accuracy of the esCCO system by continuously measuring the esCCO and TDCO.

METHODS: Forty patients who had undergone cardiac surgery with a pulmonary artery catheter were enrolled. We compared the esCCO with TDCO from mechanical ventilation to spontaneous respiration through extubation. Patients undergoing cardiac pacing during esCCO measurement, those receiving treatment with an intra-aortic balloon pump, and those with measurement errors or missing data were excluded. In total, 23 patients were included. Agreement between the esCCO and TDCO measurements was evaluated using Bland-Altman analysis with a 20 min moving average of the esCCO.

RESULTS: The paired esCCO and TDCO measurements (939 points before extubation and 1112 points after extubation) were compared. The respective bias and standard deviation (SD) values were 0.13 L/min and 0.60 L/min before extubation, and - 0.48 L/min and 0.78 L/min after extubation. There was a significant difference in bias before and after extubation (P < 0.001); the SD before and after extubation was not significant (P = 0.315). The percentage errors were 25.1% before extubation and 29.6% after extubation, which is the criterion for acceptance of a new technique.

CONCLUSION: The accuracy of the esCCO system is clinically acceptable to that of TDCO under mechanical ventilation and spontaneous respiration.