Modern approaches to blood pressure measurement

Blood pressure (BP) is usually measured by conventional sphygmomanometry. Although apparently simple, this procedure is fraught with many potential sources of error. This review focuses on two alternative techniques of BP measurement: ambulatory monitoring and self measurement.

BP values obtained by ambulatory monitoring or self measurement are characterised by high reproducibility, are not subject to digit preference or observer bias, and minimise the transient rise of the blood pressure in response to the surroundings of the clinic or the presence of the observer, the so called white coat effect. For ambulatory monitoring, the upper limits of systolic/diastolic normotension in adults include 130/80 mm Hg for the 24 hour BP and 135/85 and 120/70 mm Hg for the daytime BP and night time BP, respectively. For the the self measured BP these thresholds include 135/85 mm Hg. Automated BP measurement is most useful to identify patients with white coat hypertension. Whether or not white coat hypertension predisposes to sustained hypertension remains debated. However, outcome is better correlated with the ambulatory BP than with the conventional BP. In patients with white coat hypertension, antihypertensive drugs lower the BP in the clinic, but not the ambulatory BP, and also do not improve prognosis. Ambulatory BP monitoring is also better than conventional BP measurement in assessing the effects of treatment. Ambulatory BP monitoring is necessary to diagnose nocturnal hypertension and is especially indicated in patients with borderline hypertension, elderly patients, pregnant women, patients with treatment resistant hypertension, and also in patients with symptoms suggestive of hypotension.

The newer techniques of BP measurement are now well established in clinical research, for diagnosis in clinical practice, and will increasingly make their appearance in occupational and environmental medicine.