24-hour blood pressure differences in hypertension and normotension in bed-confined subjects

This study investigates whether the degree of hypertension may be evaluated by information derived from the 24-h blood pressure (BP) curve unrelated to the pressure height. We performed 24-h BP intra-arterial monitoring in 52 bed-confined subjects (10 normotensives, 10 borderlines, and 32 hypertensives on WHO criteria). Computer analysis of 1152 BP values per subject per 24-h revealed the following: During the night hours, the percentage of the 1152 systolic BP values greater than or equal to 160 (in mmHg) increased (or did not change if 100%) in all subjects with mean 24-h systolic BP (24-h BP) greater than 170 and it decreased (or did not change if 0%) in all subjects with 24-h BP less than 150. The change in the percentage of the 1152 diastolic BP values greater than or equal to 95 during the night hours did not correlate to either the mean 24-h diastolic or systolic BP. The higher the mean 24-h systolic BP, the lower the skewness of the distribution of the 1152 systolic BP values (p less than 0.01). No such correlation existed between the skewness of the distribution of the 1152 diastolic BP values and either the mean 24-h diastolic or systolic BP. It is concluded that both the change in systolic BP during the night hours and the skewness of its distribution during the 24-h monitoring period are correlated to the severity of hypertension.