Clinical uses of ambulatory blood pressure monitoring

In the past, the diagnosis and management of hypertension has been based on office blood pressure. However, office blood pressure is not always a true reflection of a patient's blood pressure profile. Since ambulatory blood pressure monitoring permits a large number of readings to be taken in the patient's usual environment, it may provide a more representative blood pressure profile. Indeed, ambulatory blood pressure has been better correlated than office blood pressure with the target-organ complications of hypertension. Office or white-coat hypertension (elevated blood pressure only when measured in the physician's office) has been reported in 12-21% of patients in mildly hypertensive sample populations. While office blood pressure and daytime ambulatory blood pressure values are reported to be similar in normotensive subjects, ambulatory systolic and diastolic readings in hypertensive subjects have been reported as, respectively, 4-15 mmHg and 3-10 mmHg lower than office blood pressure readings. In estimating a patient's mean blood pressure and diagnosing hypertension, the greater the number of recording hours the more accurate the estimate is likely to be; in addition, increasing the number of measurements per hour also improves accuracy and increases the sensitivity of the readings. An increased frequency and severity of target-organ damage has been associated with higher 24-h blood pressure variability. Although the diagnosis of hypertension should not be based on ambulatory blood pressure alone, there are many clinical problems for which ambulatory blood pressure can be useful.