Scitechdaily. According to research from Johns Hopkins Medicine, something as simple as where you rest your arm during the test can significantly raise the reading and potentially lead to a hypertension diagnosis that is not actually correct.
Published in JAMA Internal Medicine, the study examined how different arm positions affect blood pressure readings in adults between 18 and 80 years old. Researchers compared the guideline-recommended position, with the arm supported on a desk at heart level, against two alternatives often seen in real-world settings: resting the arm in the lap and letting the arm hang unsupported at the side.
Small Changes, Significant Effects
When participants rested their arm on their lap, systolic blood pressure readings rose by an average of 3.9 mmHg, while diastolic pressure increased by 4.0 mmHg. When the arm hung unsupported at the side, systolic pressure climbed by 6.5 mmHg and diastolic pressure by 4.4 mmHg.
Researchers say their study findings underscore the importance of adhering to clinical guidelines calling for firm arm support on a desk or other surface when measuring blood pressure.
Proper Positioning Matters
Doctors have long known that talking during a reading, crossing your legs, using the wrong cuff size, or drinking caffeine beforehand can distort results. This study adds more evidence that arm position is another overlooked factor that can quietly skew measurements.
The standard recommendation is simple: sit upright in a chair with feet flat on the floor, legs uncrossed, and the arm resting on a desk or table so the blood pressure cuff sits at heart level.
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