Evaluation of the DINAMAP blood pressure monitor in an ambulatory primary care setting.

Automatic blood pressure recorders have gained acceptance in many clinical settings. New devices have usually been validated with invasive monitoring as the "gold standard." There is a lack of sound empirical evidence, however, supporting the routine use of these monitors in ambulatory settings. This study evaluated the DINAMAP 8100, an oscillometric automated blood pressure monitor, using the Hawksley Random-Zero Sphygmomanometer as the standard. A sample of 80 normotensive and hypertensive ambulatory patients from the Department of Family Medicine at the Medical University of South Carolina were studied. A clinical trial was conducted in which readings from the DINAMAP 8100 were compared with those from the Hawksley Random-Zero Sphygmomanometer, in a 2 (instrument) X 2 (arm) X 2 (investigators) X 4 (pairs of simultaneous measurements) factorial design. The DINAMAP 8100 overestimated systolic readings (mean difference = 7.6 +/- 9.1 mmHg, P less than .0001, paired t test). More than one third of systolic measurements and one quarter of diastolic measurements were greater than 10 mmHg discrepant from the standard. The results of this study suggest that routine use of the DINAMAP 8100 would lead to serious misclassification errors in screening for hypertension and in the follow-up of known hypertensive patients. The DINAMAP 8100, therefore, is not an appropriate instrument for routine use in primary care settings.