Position Is Key

It is all about the arm when taking blood pressure. A somewhat surprising study uncovered that blood pressure readings taken on an arm that is slack can be up to 10% higher, compared with readings taken on an arm that is at a right angle to the body.

For the study, the researchers checked the blood pressure levels of 100 patients, aged 18 to 88, at the emergency room of the University of California at San Diego Medical Center. All of the participants were visiting the hospital for reasons not associated with heart problems. The researchers obtained their results after measuring each patient's blood pressure 6 times, testing in 2 arm positions (with the lower arm jutting out at a right angle to the body, and simply parallel to the upper body) while they were sitting, standing, and lying down. The findings, published recently in the Annals of Internal Medicine, showed that, among seated patients with their arms at right angles, the blood pressure readings suggested that 22% suffered from hypertension. Almost 2 times as many patients, however, received that diagnosis when their levels were measured while their arms were slack, parallel to their upper bodies.