Management of hypertensive outpatients: clinical evaluation of casual and 24-hour ambulatory blood pressure.

Knowledge of daily blood pressure profiles is now an important factor in the management of hypertension. We recently analyzed the relationship of casual blood pressure (CBP) to 24-hour blood pressure (24-h BP) in 9 hypertensive patients and 11 normotensive subjects. A 24-hour ambulatory blood pressure monitoring apparatus (24-h ABPM, A & D Co.) was used to monitor 24-h BP. Data were divided into daytime mean blood pressure (daytime mBP), night mean blood pressure (night mBP), and 24-hour mean blood pressure (24-h mBP). In each subject, the 24-h ABP pattern was highly reproducible. Analysis of CBP disclosed that both the systolic blood pressure (SBP) and diastolic blood pressure (DBP) correlated more closely with 24-h mBP than with any other parameter. In view of the high incidence of cerebral infarction during night time or rest, prior knowledge of a blood pressure change pattern from daytime mBP to night mBP in individual patients is important in the prevention of this condition. The degree of decrease from daytime mBP to night mBP varied greatly among individuals, being higher in hypertensive patients than in normotensive subjects. The degree of this change in blood pressure was difficult to predict based on the CBP change pattern following postural change or 5-min rest. In some cases, 24-h ABPM data were within the hypertensive range (systolic greater than 160 mmHg, diastolic greater than 95 mmHg) for many hours, even though CBP was within the normal range. On the other hand, the duration of this sustained hypertensive level during 24-h ABPM was sometimes short, even in subjects with elevated CBP. To deal with such discrepancies between CBP and 24-h ABPM, the duration of the sustained hypertensive level during 24-h ABPM should be given high priority in assessing the severity and prognosis of hypertension.