A comparison of non-invasive continuous finger blood pressure measurement (Finapres) with intra-arterial pressure during prolonged head-up tilt

Simultaneous intra-radial and non-invasive (Finapres, Ohmeda)blood pressures were compared during prolonged head-up tilt,in eight patients (mean age 49 years) with malignant vasovagalsyncope. Twelve tilts were performed, of which eight resultedin vasovagal syncope. The mean bias (difference between Finapresand intra-arterial pressures) for systolic pressure was +0.7mmHg (standard deviation 11.3 mmHg) and for diastolic pressurewas +5.4 mmHg (standard deviation 7 mmHg). The within-tilt precision(standard deviation of the bias) of the non-invasive measurementsvaried between 2.9–12.4 mmHg (median 4.5 mmHg) for systoliccomparisons, and 1.6–8.4 mmHg (median 4.4 mmHg) for diastoliccomparisons. In all but one tilt highly significant positiveincreases in both systolic (median 7.1 mmHg) and diastolic bias(median 81 mmHg) occurred on tilt with respect to resting pre-tiltlevels. Independent of the absolute level of agreement, thenon-invasive measurements followed changes in intra-arterialpressure closely, with 89% of beat-to-beat changes in systolicpressure, and 95% of beat-to-beat changes in diastolic pressurefollowed to within ±2 mmHg. This study suggests thatthe Finapres is well suited for use during diagnostic tilt testing,demonstrating an acceptable within-tilt precision and closelyfollowing pressure changes during vasovagal syncope.