Non-invasive continuous arterial pressure and cardiac index monitoring with Nexfin after cardiac surgery

This observational study was designed to evaluate the reliability and precision of a new digital photoplethysmographic device (Nexfin, BMEYE B.V., Amsterdam, The Netherlands) for continuous and non-invasive assessment of arterial pressure and cardiac output. Fifty consecutive adult subjects were prospectively enrolled at admission to the intensive care unit after conventional cardiac surgery and investigated hourly from T0 to T4. Simultaneous comparative systolic, diastolic, and mean arterial pressures and cardiac index (CI) data points were collected from an invasive radial artery catheter, transpulmonary thermodilution catheter, and the Nexfin device. Correlations were determined by linear regression. The Bland–Altman analysis was used to compare bias, precision, and limits of agreement. Six (12%) subjects were excluded from the analysis because of the inability to obtain a reliable photoplethysmographic signal. No complications were observed. A significant relationship was found between absolute values of photoplethysmographic and radial systolic (r2=0.56, P