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Impact of Different Arm Positions on Blood Pressure Readings
TAKE-HOME MESSAGE
- Accurate blood pressure (BP) measurement is a cornerstone of diagnosing and managing hypertension. Clinical practice guidelines for accurate BP measurement recommend supporting the arm on a desk or table. This study evaluated the impact of different arm positions on BP readings. Supporting the arm on the lap resulted in the overestimation of systolic BP by 3.9 mm Hg and diastolic BP by 4.0 mm Hg. An unsupported arm at the side led to the overestimation of systolic BP by 6.5 mm Hg and diastolic BP by 4.4 mm Hg.
- The commonly used nonstandard arm positions during BP measurement significantly overestimate BP, highlighting the need for standardized positioning to avoid overdiagnosis and overtreatment.
abstract
This abstract is available on the publisher's site.
Access this abstract nowIMPORTANCE
Guidelines for blood pressure (BP) measurement recommend arm support on a desk with the midcuff positioned at heart level. Still, nonstandard positions are used in clinical practice (eg, with arm resting on the lap or unsupported on the side).
OBJECTIVE
To determine the effect of different arm positions on BP readings.
DESIGN, SETTING, AND PARTICIPANTS
This crossover randomized clinical trial recruited adults between the ages of 18 and 80 years in Baltimore, Maryland, from August 9, 2022, to June 1, 2023.
INTERVENTION
Participants were randomly assigned to sets of triplicate BP measurements with the arm positioned in 3 ways: (1) supported on a desk (desk 1; reference), (2) hand supported on lap (lap), and (3) arm unsupported at the side (side). To account for intrinsic BP variability, all participants underwent a fourth set of BP measurements with the arm supported on a desk (desk 2).
MAIN OUTCOMES AND MEASURES
The primary outcomes were the difference in differences in mean systolic BP (SBP) and diastolic BP (DBP) between the reference BP (desk 1) and the 2 arm support positions (lap and side): (lap or side - desk 1) - (desk 2 - desk 1). Results were also stratified by hypertensive status, age, obesity status, and access to health care within the past year.
RESULTS
The trial enrolled 133 participants (mean [SD] age, 57 [17] years; 70 [53%] female); 48 participants (36%) had SBP of 130 mm Hg or higher, and 55 participants (41%) had a body mass index (calculated as weight in kilograms divided by height in meters squared) of 30 or higher. Lap and side positions resulted in statistically significant higher BP readings than desk positions, with the difference in differences as follows: lap, SBP Δ 3.9 (95% CI, 2.5-5.2) mm Hg and DBP Δ 4.0 (95% CI, 3.1-5.0) mm Hg; and side, SBP Δ 6.5 (95% CI, 5.1-7.9) mm Hg and DBP Δ 4.4 (95% CI, 3.4-5.4) mm Hg. The patterns were generally consistent across subgroups.
CONCLUSION AND RELEVANCE
This crossover randomized clinical trial showed that commonly used arm positions (lap or side) resulted in substantial overestimation of BP readings and may lead to misdiagnosis and overestimation of hypertension.
Additional Info
Arm Position and Blood Pressure Readings: The ARMS Crossover Randomized Clinical Trial
JAMA Intern Med 2024 Oct 07;[EPub Ahead of Print], H Liu, D Zhao, A Sabit, CH Pathiravasan, J Ishigami, J Charleston, ER Miller, K Matsushita, LJ Appel, TM BradyFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
The latest clinical practice guidelines detail key steps for accurate blood pressure (BP) measurement, which include appropriate cuff size selection, back support, feet flat on the floor with ankles uncrossed, and appropriate arm position, with the midcuff positioned at the heart level and the arm supported on a desk or table. The physiological mechanisms explaining why BP measurements are higher when the arm is not appropriately positioned or supported are discussed.
If a patient's BP is measured while they are seated in the dental chair, the arm and foot positions are nonstandard and the measurement will be inaccurate. Dental team members should be aware of these clinical practice guidelines and follow them to avoid referring the patient to a physician for suspected hypertension or unnecessarily postponing/canceling a dental procedure.