Narrator: This is Science Today. When it comes to measuring blood pressure, it turns out that arm position matters. Dr. Davis Guss, director of Emergency Room Services at the University of California, San Diego, led a study measuring the blood pressure of 100 emergency room patients a total of six times per patient, and found a significant difference between readings measured with the arm at the side compared to the arm in a perpendicular position.

Guss: We found that regardless of body position, about twice as many patients met the criteria for hypertension when their arm was parallel to their body as compared to when their arm was perpendicular to their body.

Narrator: The American Heart Association recommends that blood pressure be measured with the cuff placed at the level of the heart with the elbow slightly flexed.

Guss: I’m not suggesting that blood pressures have been measured incorrectly around the country by health care providers, all I’m trying to point out is that arm position does matter and that it should be consistent. It’s probably even more important nowadays since there are so many people monitoring their blood pressure at home.

Narrator: For Science Today, I’m Larissa Branin.