The Potential for Inaccurate Blood Pressure Readings

Blood pressure readings vary based on arm positioning, and may lead to misinformation. A study in JAMA Internal Medicine reports that commonly used lap or side arm positioning, versus desk positioning, for BP monitoring can result in hypertension misdiagnosis. Testing 133 participants aged 18 to 80 years, researchers took BP readings multiple times, with the arm in different positions. In all, 12 BP measurements were taken for each participant.

Why the difference? The distance between the BP cuff and the heart can either lead to an increase in hydrostatic pressure in the brachial artery, or a decreased venous return. Muscle contractions from an improperly supported arm can cause increased BP. The researchers state that, “Proper arm position may be even more important for individuals at higher risk for cardiovascular disease, particularly those with hypertensive SBP.”

The study concluded: “This crossover randomized clinical trial shows that not adhering to the guideline-recommended arm position and support during BP measurement can result in overestimation of BP by 4 to 10 mm Hg. This degree of BP error could lead to a substantial number of people being overdiagnosed with hypertension.”