Use of ambulatory blood pressure monitoring in the management of antihypertensive therapy.

The recent development of ambulatory blood pressure (ABP) monitoring techniques has improved recording of blood pressure in therapeutic trials and in the clinical setting. The application of ABP differs according to which of these 2 applications is being considered. In therapeutic trials, a placebo control is required. The large quantity of precise data acquired with ABP monitoring allows the study of a limited number of patients; it also allows individual study of patients with a 'white coat' response (i.e. elevated blood pressure in response to examination by the clinician). Analysis of data from ABP monitoring may include the following: comparison of mean blood pressure values over 24 hours, daytime or night-time, or over any other selected time period; 24-hour blood pressure profiles, or analysis hour-by-hour, giving true chronotherapy, and providing data regarding the wearing-off of a drug effect or loss of therapeutic control; analysis of blood pressure at particular times, such as on waking; or specific examination of nonresponders. In individual patients, ABP monitoring should be reserved for specific indications. It can be used before initiation of treatment to confirm the necessity for treatment, especially in the context of hypertension at rest or the 'white coat' effect. With established treatment, ABP monitoring can be used in patients with resistant hypertension, in severe hypertension to examine loss of blood pressure control over time or inversion of the day/night cycle, and in patients with a specific illness, e.g. diabetes, in order to obtain the lowest blood pressure readings possible. Examination of these factors assists clinicians to accurately decide upon the timing and frequency of antihypertensive therapy.