A randomized clinical trial of 133 adults published in JAMA Internal Medicine showed that arm position can have an effect on blood pressure (BP) readings. When subjects supported their arm on their lap, it resulted in systolic BP readings overestimated by 3.9 mm Hg and diastolic BP readings overestimated by 4.0 mm Hg. Additionally, an unsupported arm at the subject’s side overestimated systolic BP by 6.5 mm Hg and diastolic BP by 4.4 mm Hg. The findings were more pronounced among higher-risk groups, in which systolic BP was overestimated by approximately 9 mm Hg among individuals with hypertensive BP when their arm was positioned at the side unsupported. Clinical guidelines state that the arm should be supported on a surface with the middle of the cuff positioned at heart level, although other nonstandard positions are used in practice today. Study subjects ages 18 to 80 had their BP measured multiple times in the correct position and the 2 nonstandard positions for a total of 12 measurements.
Something to keep in mind: Authors point out the potential for overdiagnosis of hypertension when the arm position does not follow guidelines. They also attribute the lack of adherence to guidelines to a lack of clinician awareness as well as limitations in training, resources, and equipment.
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