WHY AMBULATORY BLOOD-PRESSURE MONITORING

Factors that affect the reliability and accuracy of blood pressure mea surements are reviewed, and new technologies for measuring blood press ure are discussed. Blood pressure measurements obtained in an office, hospital, or clinic are subject to variation and error. Reasons for va riations include the wrong cuff size, improper inflation or deflation technique, and patient apprehension (''white-coat syndrome''). Ambulat ory blood pressure monitoring (ABPM) involves the use of a fully autom ated standard arm cuff that is inflated at predetermined intervals by a small battery-powered pump unit. The most reliable ABPM method is th e oscillometric method, which detects subtle changes in air pressure w ithin the cuff system caused by fluctuations of the brachial artery. T he process for interpreting 24-hour ABPM data is still evolving. Twent y-four-hour ABPM has been shown to eliminate white-coat hypertension a nd is also useful for assessing patients whose blood pressure is inapp ropriately high in the absence of end organ damage, monitoring persons at risk of developing hypertension because of their race or family hi story, determining a medication's 24-hour effect on blood pressure, an d assessing the early-morning rapid rise in blood pressure, which has been linked to an increased risk of nonembolic stroke and myocardial i nfarction. ABPM enables identification of patients whose blood pressur e is elevated in the office but normal at home, allows more appropriat e screening of patients for clinical trials, gives reproducible values , and enables evaluation of drug duration and action.