Ambulatory blood pressure monitoring in the diagnosis of hypertension.

Noninvasive ambulatory blood pressure monitoring is a tool that may be useful for selected patients. Interest in the technology has increased because of errors and variability in clinic measurements and because of white-coat hypertension. White-coat hypertension is not benign and is associated with increased left ventricular mass and altered lipid and endocrine profiles. Ambulatory blood pressure may be useful in white-coat, borderline, and drug-resistant hypertension. Patient hook-up requires a skilled technician to adjust and calibrate the equipment and instruct the patient. Blood pressure and heart rate data should be analyzed with respect to diary entries. Observations of the diurnal curve, 24-hour, daytime, and nighttime mean blood pressure and blood pressure load are the key items in report interpretation. A 24-hour blood pressure mean of at least 134-139/84-87 mm Hg is probably indicative of hypertension. A blood pressure load of greater than 40% predicts target-organ damage. A reduced nocturnal decline is seen in many diseases but more importantly is associated with more target organ damage. The equipment used for ambulatory monitoring should be independently validated against the most recent AAMI or British Hypertension Society protocols. The performance of these devices is acceptable at rest but poor with activity. Group test-retest performance is excellent, but there is much more variability in individual patients. The variability in individuals is probably due to differences in activity and behavior. This has implications in the interpretation of ambulatory blood pressure parameters. Complications are most often related to excess repetitive inflations. Ambulatory blood pressure monitoring affects sleep mildly. Ongoing studies will define the place of ambulatory blood pressure monitoring in the care of patients.