Difference in the nocturnal behaviour of blood pressure between monitorings with the arm-cuff method and with the finger-volume oscillometric method

The nocturnal behaviour of blood pressure obtained by a new portable device for monitoring ambulatory blood pressure (ABPM 630) was compared with that obtained by a finger-volume oscillometric device (BP-100); the former uses a conventional arm-cuff inflated by CO2 gas to eliminate the noise of the motorized pump, and is based on a cuff-oscillometric as well as the Korotkoff sound technique (microphone method). With the microphone method in ABPM 630, the mean differences from the conventional auscultatory method were -0.28 +/- 6.15 mmHg (mean +/- s.d.) for systolic and 0.96 +/- 6.28 mmHg for diastolic blood pressure, and there was a highly significant correlation between blood pressure values measured by the ABPM 630 and by the auscultatory method. In 40 patients with mild to moderate hypertension 24-h blood pressure was monitored simultaneously with the ABPM 630 and BP-100. The daytime average of systolic blood pressure measured with the ABPM 630 was similar to that measured with the BP-100, whereas the night-time average assessed by the former was significantly higher than that assessed by the latter. Arm-cuff inflation by ABPM 630 caused some degree of sleep disturbance in 35 of 40 subjects, whereas finger-cuff inflation scarcely disturbed the sleep. The performance of the ABPM 630 was excellent.