Blood pressure readings taken with arms parallel or extended in the same direction as the body are up to 10 percent higher than readings taken with recommended positioning --- elbow flexed at a right angle to the body and at heart level, according to a study in the January 6th issue of the Annals of Internal Medicine.

The American investigators noted that documented blood pressure readings are often the sole determinant of diagnosis and treatment selection for hypertension, which makes it all the more important that readings be taken with designated and consistent arm positioning. A previously published study had found that 73 percent of health care workers failed to use proper arm positions and blood pressure cuff positions as defined by the American Heart Association.

In the current study, researchers measured blood pressure in 100 emergency room patients ages 18 to 88 years who were seen for a chief symptom unlikely to be associated with cardiovascular instability. Each patient’s blood pressure was measured 6 times ? in perpendicular (right angle, flexed at elbow) and parallel arm positions while lying, sitting, or standing. The proportion of seated patients classified with hypertension was 22 percent with the arm perpendicular and 41 percent with the arm parallel to the body.

“In every body position, the systolic and diastolic blood pressure measured with the arm perpendicular to the body was significantly lower than with the arm in a parallel position,” the authors concluded.