A comparison of continuous non-invasive arterial pressure with invasive radial and femoral pressure in patients undergoing cardiac surgery.

ABSTRACT

BACKGROUND: Non-invasive continous monitoring of finger arterial pressure has gained increasing interest. The aim of the present study was to compare the accuracy of non-invasive reconstructed brachial artery pressure by the Nexfin™ device (NFAP) with invasive femoral (IFAP) and radial (IRAP) artery pressure before and after cardiopulmonary bypass (CPB). METHODS: Fifty patients scheduled for elective coronary surgery were studied before and after CPB, respectively. Each patient was monitored with the non-invasive system, and both an indwelling femoral and radial arterial catheter. A passive leg raising maneuver was also performed before and after CPB. Measurements included mean (MAP), systolic (SAP) and diastolic (DAP) arterial pressure by NFAP (MAP,SAP,DAP(NFAP)), IFAP (MAP,SAP,DAP(IFAP)) and IRAP (MAP,SAP,DAP(IRAP)). Percentage changes of MAP for all measurement sites were also calculated. RESULTS: There was a moderate correlation between MAP(NFAP) and MAP(IFAP) both before (r=0.64, P<0.0001) and after (r=0.57, P<0.0001) CPB, with a percentage error (PE) of 29% and 27%, respectively. Correlation coefficients between MAP(NFAP) and MAP(IRAP) were r=0.53, P<0.0001 (PE 34%) before and r=0.54, P<0.0001 (PE 29%) after CPB. There was a significant correlation in percentage changes between ∆MAP(NFAP) and ∆MAP(IFAP) before (r=0.70, P<0.0001) and after (r=0.71, P<0.0001) CPB and for ∆MAP(NFAP) and ∆MAP(IRAP) (r=0.67, P<0.0001; r=0.74, P<0.0001), respectively. CONCLUSION: Non-invasive, reconstructed brachial artery pressure showed moderate correlation compared with both invasive femoral and radial artery pressure. Furthermore, the non-invasive monitoring system was able to reflect percentage changes in mean arterial pressure in a moderate fashion.