Why ambulatory blood pressure monitoring?

Factors that affect the reliability and accuracy of blood pressure measurements are reviewed, and new technologies for measuring blood pressure are discussed. Blood pressure measurements obtained in an office, hospital, or clinic are subject to variation and error. Reasons for variations include the wrong cuff size, improper inflation or deflation technique, and patient apprehension ("white-coat syndrome"). Ambulatory blood pressure monitoring (ABPM) involves the use of a fully automated standard arm cuff that is inflated at predetermined intervals by a small battery-powered pump unit. The most reliable ABPM method is the oscillometric method, which detects subtle changes in air pressure within the cuff system caused by fluctuations of the brachial artery. The process for interpreting 24-hour ABPM data is still evolving. Twenty-four-hour ABPM has been shown to eliminate white-coat hypertension and is also useful for assessing patients whose blood pressure is inappropriately high in the absence of end organ damage, monitoring persons at risk of developing hypertension because of their race or family history, determining a medication's 24-hour effect on blood pressure, and assessing the early-morning rapid rise in blood pressure, which has been linked to an increased risk of nonembolic stroke and myocardial infarction. ABPM enables identification of patients whose blood pressure is elevated in the office but normal at home, allows more appropriate screening of patients for clinical trials, gives reproducible values, and enables evaluation of drug duration and action.