Increasing daytime vascular resistance with progressive hypertension in ambulant patients.

Twenty-four-hour recordings of intra-arterial blood pressure, heart rate, and calculation of the index of peripheral vascular resistance were obtained in 20 untreated ambulant hypertensive patients during their routine activities outside the hospital. Blood pressures and heart rates were higher during the day, with a mean night-to-day increase of 22%, 34%, and 26%, for systolic, diastolic, and mean pressures, respectively. The average increase in the heart rate was 32%. Overall, the index of resistance was lower (12%) during the day. However, eight patients (40%) demonstrated no change or an increase in the peripheral vascular resistance. Six of these eight patients had an average daytime mean pressure above 120 mm Hg. There was a significant decrease in the index of resistance during exercise in all but one of the 16 subjects. Hemodynamic parameters of 1 hour before and 1 hour after awakening were similar to the values obtained during the entire night and the rest of the day, respectively. Our data suggest that in patients with "progressive" hypertension, the ability to decrease vascular resistance from night to day is compromised.