Measurement of blood pressure

Methods available to measure blood pressure (BP) include 24-hour ambulatory BP monitoring, automated clinic BP measurement, nonautomated clinic BP measurement and home BP monitoring.

Use of 24-hour ambulatory BP monitoring for assessment of BP outside the clinic provides the most accurate and comprehensive information and reveals variations in BP during daily life. It is particularly useful if atypical presentations of BP (eg white-coat hypertension, masked hypertension, nocturnal nondipping) are suspected. Ambulatory BP monitoring is reimbursed by the Medicare Benefits Scheme for the diagnosis of hypertension.

Measurements taken in the clinic are useful but are an inferior indication of the patient’s usual BP. Assessment of clinic BP can be greatly improved by automated nonobserved BP measurements; this involves measurement of BP by a calibrated automated oscillometric device after the patient has been seated and resting alone in a quiet room for at least 5 minutes. The first reading is disregarded and an average of the second and third readings is calculated to determine the automated clinic BP. Atypical presentations of BP can be detected by taking multiple measurements on separate occasions.

Many patients have a home BP monitoring machine or take advantage of BP monitoring services in local pharmacies; these records are a useful supplement to clinic BP measurement.

More detailed information on BP measurement can be found in the Heart Foundation guideline.