Before seeing a doctor, a nurse will go over your medical history, jot down your height and weight, and check your vitals. These are common patient intake practices and usually aren't cause for concern. But there's one step in the process that, when its results are statistically high, can raise serious alarm bells—and that's your blood pressure reading.
If you also suffer from white coat syndrome (thank you, anxiety), you might be accustomed to the nurse testing your blood pressure multiple times, including at the end of your visit, to gather an accurate reading. Well, researchers now say that nerves might not always be to blame. According to a new study published in the journal JAMA Internal Medicine, some standard blood pressure test techniques can lead to skewed results and consequently prompt unnecessary medical diagnoses, like hypertension.
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Hypertension is the fancy medical term for high blood pressure, which is a reading of 130/80 or higher, per the American Heart Association (AHA). High blood pressure can trigger stroke, vision loss, heart failure, heart attack, and kidney disease.
The AHA classifies a blood pressure reading of 120/80 or less as “normal,” while 120-129/80 is considered “elevated.” Smoking, alcohol, and diets that are rich in sodium and saturated fat all contribute to high blood pressure. Maintaining a healthy weight and exercising regularly can help keep your blood pressure in the healthy range, says the AHA.
However, the testing method used to measure your blood pressure also plays a significant role. According to the study, having a supported arm (i.e., propping it up on a table versus having it hang by your side) could be the difference between a normal and “markedly higher” reading.
Researchers discovered this after analyzing three different arm positions that are widely used by medical professionals to measure blood pressure. These include the arm supported on a desk, the arm resting on the person’s lap, and the arm relaxed, hanging by the person’s side (AKA unsupported). It should be noted that standard clinical guidelines prioritize the first option.
For the experiment, researchers conducted 12 rounds of blood pressure measurements on 133 adults between the ages of 18 and 80. The participants cycled through each of the arm positions at random.
Results showed that the most accurate reading comes from having your arm supported on a desk, with the monitor cuff strapped on at heart level. This arm position had an average reading of 126/74, which is healthy.
Meanwhile, the average reading of the other two arm positions fell into the hypertension level. The arm-resting-on-lap position had an average rating of 130/78, while the unsupported, hanging arm position had an average reading of 133/78.
“Health care providers need to be reminded about the importance of taking the time to do these steps properly,” Tammy Brady, PhD, the study’s senior author, told CNN. “I just hope that it raises awareness regarding how important things like arm position are to blood pressure measurement accuracy.”
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A hypertension expert herself, Brady, who serves as medical director of the pediatric hypertension program at Johns Hopkins Children’s Center, admitted that even she was surprised by the study’s results.
“I did not expect there to be that much of a difference when the arms were placed in the two alternative positions. We tested those positions because those are the positions that most people have their blood pressure measured, according to data and personal observations,” she explained. “We thought there’d be a difference, but I was surprised by how much of a difference there was.”
If you think your blood pressure reading is inaccurate, speak up. Researchers say “the latest clinical practice guidelines emphasize several key steps,” including wearing the right cuff size, having adequate back support, uncrossed legs with feet firmly planted on the ground, and an arm position that gives proper support.
