Arm Position and Blood Pressure Readings: The ARMS Crossover Randomized Clinical Trial.
Level 2 - randomized trial
Individual randomized crossover clinical trial
PubMed 39373998 · doi:10.1001/jamainternmed.2024.5213
What was done
This randomized crossover clinical trial evaluated the impact of arm positioning on blood pressure (BP) measurements in 133 adults aged 18 to 80 years in Baltimore, Maryland. Participants were randomly assigned to undergo sets of triplicate BP measurements in three positions: arm supported on a desk (desk 1; reference), hand supported on the lap (lap), and arm unsupported at the side (side). All participants also completed a fourth set supported on a desk (desk 2) to control for intrinsic BP variability. The primary outcome was the difference in differences in mean systolic BP (SBP) and diastolic BP (DBP) comparing lap and side positions against the desk reference, with subgroup analyses by hypertension status, age, obesity, and recent healthcare access.
What was found
Among the 133 participants (mean age 57 years, 53% female, 36% with baseline SBP 130 mm Hg or higher, and 41% with BMI 30 or higher), nonstandard arm positions produced statistically significant BP elevations compared to desk support. The lap position yielded a difference in differences of 3.9 mm Hg (95% CI, 2.5-5.2) for SBP and 4.0 mm Hg (95% CI, 3.1-5.0) for DBP. The side position yielded an SBP increase of 6.5 mm Hg (95% CI, 5.1-7.9) and a DBP increase of 4.4 mm Hg (95% CI, 3.4-5.4). These overestimations were consistent across evaluated subgroups.
Why it matters
Commonly used nonstandard arm positions during routine clinical practice markedly overestimate both systolic and diastolic blood pressure. Adhering to clinical guidelines that require arm support on a desk at heart level is critical to prevent hypertension misdiagnosis and unnecessary medication.
Limits
The study was conducted at a single geographic site with a modest sample size of 133 participants. The abstract does not report long-term clinical outcomes, the exact rate of misclassification in practice, or whether results generalize across diverse automated and manual device types.
Cited by
- supports Arm position significantly alters blood pressure readings on automated cuffs, such that placing an arm above the head versus at the level of the right atrium produces a large difference in measured pressure.