Faulty blood pressure readings can put lives at risk. A new randomized clinical trial shows that commonly used arm positions (lap or side) result in substantially higher blood pressure readings which can lead to false diagnoses and over-treatment. To measure blood pressures accurately, the arm should be supported at heart level. The authors call for clinical guidelines to include this new evidence-based knowledge.
Question What is the effect of commonly used arm positions on blood pressure (BP) measurements compared to the standard, recommended position?
Findings This crossover randomized clinical trial of 133 adults showed that supporting the arm on the lap overestimated systolic BP by 3.9 mm Hg and diastolic BP by 4.0 mm Hg. An unsupported arm at the side overestimated systolic BP by 6.5 mm Hg and diastolic BP by 4.4 mm Hg, with consistent results across subgroups.
Meaning Commonly used, nonstandard arm positions during BP measurements substantially overestimate BP, highlighting the need for standardized positioning.
