Monitoring 24-hour blood pressure in a drug trial. Evaluation of a noninvasive device.

To test the usefulness of noninvasive ambulatory 24-hour blood pressure recording, the Del Mar Avionics system was used in a double-blind clinical trial in which 31 hypertensive patients were randomly allocated to receive placebo or pafenolol (25 mg or 50 mg), a novel, long-acting, highly selective beta-blocker, once daily. The results of 24-hour blood pressure and heart rate recording after 4 weeks of treatment were compared with a previous 24-hour recording performed after a 4-week placebo run-in period using the 3-hour mean of recordings performed every 7.5 minutes both day and night. Furthermore, 24-hour means were analyzed in each patient before and after 4 weeks. The system was easy to use and, judging from two placebo periods in the same patients, the reproducibility was good. The 24-hour blood pressure and heart rate recordings showed a clear dose-response relationship for pafenolol that could not be detected by ordinary casual readings. A daily dose of 25 mg of pafenolol significantly reduced blood pressure during the 9 hours after tablet intake (p less than 0.01), while 50 mg per day of pafenolol resulted in a significant reduction throughout the 24-hour period (p less than 0.01). The same pattern was seen for heart rate, which indicates a greater degree of beta-blockade during treatment with the higher dose. These results indicate that the tested noninvasive equipment is a useful tool for monitoring ambulatory 24-hour blood pressure. It gives important information impossible to obtain from single casual readings. This noninvasive method should be further evaluated to define its place in clinical work and as a research tool.