ACCURACY OF A CONTINUOUS BLOOD-PRESSURE MONITOR BASED ON ARTERIAL TONOMETRY

A validation study of the continuous noninvasive tonometric blood pres sure monitor called JENTOW was performed in 20 normotensive subjects a nd 10 hypertensive patients. Tonometric and intra-arterial blood press ures were simultaneously recorded at supine rest and during a Valsalva maneuver and tilting test. The results of the strict evaluation of th e instrument's capacity for reproducing intra-arterial blood pressure were as follows: 1) The overall frequency response of the transcutaneo us blood pressure-monitoring system based on arterial tonometry was fl at, with negligible delay to intra-arterial blood pressure in the rang e of 0-5 Hz. 2) The largest discrepancy between intra-arterial and ton ometric pressure waveforms was found at the early systolic phase; exce pt for this phase, the tonometric waveform was almost equal to the int ra-arterial waveform. 3) The beat-to-beat variability of tonometric pr essure corresponded to that of intra-arterial pressure almost perfectl y in the physiologically significant frequency range of 0-0.5 Hz. 4) D uring resting conditions, the averages of the systolic and diastolic v alues measured tonometrically corresponded well to those measured intr a-arterially. 5) The changes in the between-method discrepancy of bloo d pressure values during the Valsalva maneuver were statistically sign ificant but small (<5 mm Hg). 6) No significant effect of postural til ting was found on the between-method discrepancy. We conclude that thi s method is clinically acceptable and reliable except for its limited capacity for recording the higher frequency intra-arterial waveform an d for responding to the relatively rapid and large transient changes i n blood pressure.