Your Arm Position Can Make Blood Pressure Readings Inaccurate

Think back to the last time you went to the doctor’s office. Chances are, at the start of the visit, they took your temperature, pulse, and blood pressure—your “vitals.” But how did they take your blood pressure? The medical literature that describes safe blood pressure ranges is all based on readings taken with the patient sitting with feet flat on the floor, legs uncrossed, back supported, and the testing arm supported by a desk at mid-heart level. But if the blood pressure is measured with the person in a different position—say, perched on the edge of an exam table, legs dangling, and an arm hanging at the side—the readings given by a blood pressure monitor can be distorted. In a recent study published in the journal JAMA Internal Medicine, researchers found that arm position could account for as much as a 7mmHg difference in pressure readings. That difference could be enough to incorrectly classify some people as hypertensive. Dr. Tammy Brady, medical director of the Pediatric Hypertension Program at Johns Hopkins University, joins Ira to talk about the art of blood pressure measurement, how to better track your own blood pressure, how to find blood pressure monitors that have been properly validated, and the importance of advocating for yourself in medical settings. Transcript for this segment will be available after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.