Comparison of continuous non-invasive finger arterial pressure monitoring with conventional intermittent automated arm arterial pressure measurement in patients under general anaesthesia

Background: For a majority of patients undergoing anaesthesia for general surgery, mean arterial pressure (MAP) is only measured intermittently by arm cuff oscillometry (MAP(iNIAP)). In contrast, the Nexfin (R) device provides continuous non-invasive measurement of MAP (MAP(cNIAP)) using a finger cuff. We explored the agreement of MAP(cNIAP) and MAP(iNIAP) with the gold standard: continuous invasive MAP measurement by placement of a radial artery catheter (MAP(invasive)). Methods: In a total of 120 patients undergoing elective general surgery and clinically requiring MAP(invasive) measurement, MAP(iNIAP) and MAP(cNIAP) were measured in a 30 min time period at an arbitrary moment during surgery with stable haemodynamics. MAP(iNIAP) was measured every 5 min. Results: Data from 112 patients were analysed. Compared with MAP(invasive), modified Bland-Altman analysis revealed a bias (SD) of 2 (9) mm Hg for MAP(cNIAP) and -2 (12) mm Hg for MAP(iNIAP). Percentage errors for MAP(cNIAP) and MAP(iNIAP) were 22% and 32%, respectively. Conclusions: In a haemodynamically stable phase in patients undergoing general anaesthesia, the agreement with invasive MAP of continuous non-invasive measurement using a finger cuff was not inferior to the agreement of intermittent arm cuff oscillometry. Continuous measurements using a finger cuff can interchangeably be used as an alternative for intermittent arm cuff oscillometry in haemodynamically stable patients, with the advantage of beat-to-beat haemodynamic monitoring