How to measure blood pressure: focus on general practice

An accurate blood pressure (BP) assessment is needed to diagnose and treat hypertension. Oscillometric devices are increasingly used to estimate BP instead of the auscultation-based methods.1 The estimation algorithms are device specific and only validated devices recommended by the British and Irish Hypertension Society should be used in health care. Meticulous choice of correct size of BP cuffs is crucial. For arms requiring an extra-large cuff, using a large cuff overestimates systolic BP by 9.6 mmHg and a regular cuff overestimates systolic BP by 19.5 mmHg.2 Conversely, using too large a cuff underestimates BP. Circumference guides on cuffs must be observed and, if in doubt, arm circumference must be measured before BP measurement. BP can be measured with a range of techniques and settings. Each have their own pros and cons. Taken in clinical settings, office BP remains the most widely used approach for hypertension screening, BP assessment in acute settings, monitoring of BP control, and in cardiovascular risk calculators, such as QRISK3. The approach is prone to substantial measurement errors unless performed by trained staff who strictly adhere to measurement guidelines (Box 1).3 Failure to measure both arms and adopt results from the higher reading arm can misclassify up to 12% of people with hypertension and underestimates cardiovascular risk.4 Additional considerations are needed for BP measurement in pregnant women, patients with obesity, and patients with irregular heart rhythm (Table 1). Office BP may substantially differ from out-of-clinic BP, leading to overdiagnosis of sustained hypertension (white-coat hypertension) or its underdiagnosis (masked hypertension). Despite the limitations, office BP is recommended by the National Institute for Health and Care Excellence (NICE) for monitoring the response to lifestyle changes or antihypertensive pharmacotherapy.3 | | ||