Ambulatory monitoring in the evaluation of blood pressure in patients with borderline hypertension and the role of the defense reflex.

The differences between blood pressure (BP) readings taken in the clinic and during normal daily activities were assessed in two studies using a noninvasive ambulatory BP monitor (Avionics). In the first study 30 untreated hypertensive patients (17 with borderline pressures, average diastolic less than or equal to 95, and 13 established hypertensives, diastolics above 95) and 5 normotensive subjects had 30 readings taken in the physician's office and 30 while at home. Conventional sphygmomanometer BPs were also recorded in the office. In the borderline group home BPs were significantly lower than clinic BPs, whereas this difference was less marked for the established and normotensive group. In the second study BP was measured every 15 minutes for 24 hours in 25 normal subjects, 25 borderline and 25 established hypertensives, and readings categorized according to four recording situations: physician's office, work, at home, and sleep. BPs in all groups were highest at work and lowest asleep, and directional changes were similar. Both hypertensive groups showed higher BPs in the physician's office than at home, while normal subjects showed no difference. BPs recorded in the physician's office were good predictors of 24 hour average BP in normal and established hypertensive subjects, but not in the borderline group: in such patients 24 hour monitoring may be of particular value in evaluating the need for treatment.