Twenty-four-hour ambulatory noninvasive continuous finger blood pressure measurement with PORTAPRES: a new tool in cardiovascular research.

PORTAPRES model 1 is a portable 24 h continuous noninvasive blood pressure recorder based on the same principles as FINAPRES, the volume-clamp method of Peñaz and the physiocal criteria of Wesseling. In addition, PORTAPRES measures two adjacent fingers in alternation every 30 min and automatically corrects hydrostatic effects due to height changes of the measured fingers. The device measures 255 x 210 x 60 mm and weights about 3,000 g, including a lithium battery pack and a TEAC cassette FM instrumentation tape recorder to record the finger pressure wave form, the height signal, and beat-to-beat derived systolic, mean and diastolic pressure as well as heart rate. It appears to be an excellent new tool for cardiovascular research in humans. In a randomized, placebo-controlled, double-blind, crossover study the effect of oral administration of 2.5 mg cilazapril, a new potent long-acting, nonsulfhydryl-group angiotensin converting enzyme (ACE) inhibitor, given once daily for 7 days, was investigated in 16 healthy young men (mean age 25.3 +/- 1.6 years). Finger blood pressure and heart rate were measured with PORTAPRES for 24 h during everyday life and during standardized laboratory tasks, once about 1 to 2 h A.M. and once about 10 to 11 h P.M. once about 1 to 2 h A.M. and once about 10 to 11 h P.M. after drug administration. Physical activity was controlled by integrated thigh-EMG. Using stepwise multiple linear regression analysis it was shown that based on 64 s mean values, this measure of physical activity explains 34-77% of the heart rate variance within 24 h (median 53%), 10-52% (31%) of systolic, and 4-38% (25%) of diastolic blood pressure variance when up to 20 time lags of the EMG signal were introduced as possible predictors. This indicates that varying degrees of physical activity have a great impact on everyday blood pressure and heart rate. After one week cilazapril did not alter 24-h means of systolic and diastolic blood pressure or heart rate significantly, but reduced 30 min averages of both systolic and diastolic blood pressure by 6-10 and 4-6 mm Hg between 1 1/2 and 4 or 6 h after drug administration respectively during everyday life (p = 0.0067-0.066) without changing heart rate. On adjusting cardiovascular variables for the effects of physical activity, this blood pressure reduction was confirmed.(ABSTRACT TRUNCATED AT 400 WORDS)