Certain arm positions commonly used for blood pressure checks may lead to inaccurate results. Here’s the right way to do it

CNN
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A brand new examine discovered that having your arm within the flawed place throughout blood strain checks — both at house or the physician’s workplace — may end up in readings “markedly increased” than when your arm is within the recommended position: appropriately supported on a desk with the center of the cuff positioned at coronary heart degree.

This implies that not constantly having your arm positioned and supported appropriately throughout a blood pressure reading may end in a misdiagnosis of hypertension, which some specialists fear may presumably result in pointless therapy.

The examine, printed Monday within the journal JAMA Internal Medicine, discovered that having your arm resting within the lap throughout a blood strain studying can result in an overestimated systolic blood strain measurement by 3.9 mm Hg and overestimated diastolic studying by 4 mm Hg. And having your arm hold by your aspect can result in an overestimated systolic studying by 6.5 mm Hg and overestimated diastolic studying by 4.4 mm Hg.

Blood pressure is measured in models of millimeters of mercury or mm Hg, which consists of two numbers – the higher or systolic studying and the decrease or diastolic studying. An individual is taken into account as having high blood pressure or hypertension if they’ve constant readings of 130/80 or increased.

“Well being care suppliers must be reminded concerning the significance of taking the time to do these steps correctly,” mentioned the examine’s senior creator Dr. Tammy Brady, who serves as vice chair for medical analysis within the division of pediatrics on the Johns Hopkins College Faculty of Drugs and medical director of the pediatric hypertension program at Johns Hopkins Kids’s Middle.

“I simply hope that it raises consciousness concerning how necessary issues like arm place are to blood strain measurement accuracy,” Brady mentioned concerning the examine.

“I additionally hope this examine educates sufferers, empowering them to advocate for correct measurement once they’re in a clinic setting,” she mentioned. “But in addition, as a result of so many sufferers depend on house blood strain measurements for hypertension analysis, analysis, and therapy, I hope this educates them on find out how to correctly place their arms as a result of our findings completely lengthen to measurements within the house.”

The researchers, from Johns Hopkins University, recruited 133 adults from Baltimore, Maryland, between August 2022 and June 2023, to take part within the examine. The adults, ages 18 to 80, had been randomly assigned to have their blood strain measured whereas their arms had been positioned in three other ways: supported on a desk, as is the beneficial commonplace follow; supported on their lap; or hanging by their aspect, unsupported.

Every examine participant underwent a complete of 12 blood strain measurements with their arms in every of these varied positions.

Among the many contributors, when their arms had been supported on a desk as beneficial by the usual medical tips, the common of their blood strain studying was 126/74, the researchers discovered.

However when the contributors’ arms had been resting of their laps throughout their readings, the common blood strain studying was 130/78, and when their arms had been hanging by their sides, the common of their readings was 133/78.

“I didn’t count on there to be that a lot of a distinction when the arms had been positioned within the two different positions. We examined these positions as a result of these are the positions that most individuals have their blood strain measured, based on knowledge and private observations,” Brady mentioned. “We thought there’d be a distinction, however I used to be stunned by how a lot of a distinction there was.”

The researchers wrote that there are a number of physiological the reason why blood strain measurements may very well be erroneously increased when the arm shouldn’t be adequately positioned or supported. A larger vertical distance between the guts and the place the cuff is positioned can improve hydrostatic strain within the arteries, or the strain of the blood towards the wall, as a result of gravity’s pull, resulting in an overestimation of blood strain. And an unsupported arm can result in the muscle contracting, which can trigger a rise in blood strain.

The brand new examine findings are in step with some separate earlier analysis that has proven unsupported arm positions or the arm being positioned below heart level can overestimate a blood strain studying.

“We all know that arm place impacts the blood strain studying, what this examine does is offers us a extra exact measure of simply how a lot this has an influence,” Dr. Nichola Davis, vp and chief inhabitants well being officer at NYC Health and Hospitals, who was not concerned within the examine, mentioned in an e-mail.

“That is seen in contributors with all ranges of blood strain, however extra pronounced in contributors with elevated blood strain. These are necessary findings as a result of we diagnose and deal with hypertension based mostly on blood strain readings, and these readings must be correct,” Davis mentioned within the e-mail.

The researchers wrote within the examine that the “newest medical follow tips emphasize a number of key steps for correct measurement,” together with:

Sporting the suitable cuff dimension is essential as a result of an improperly sized blood pressure cuff can distort blood pressure readings taken by automated blood strain units. One examine, printed final yr within the journal JAMA Internal Medicine, discovered that utilizing commonplace, regular-sized blood strain cuffs resulted in “strikingly inaccurate” readings if a affected person required otherwise sized ones, notably for contributors who match bigger cuffs.

There are some steps individuals ought to take earlier than they’ve their blood strain checked, mentioned Dr. Gail Adler, a cardiovascular endocrinologist and co-specialist within the Hypertension Clinic at Brigham and Girls’s Hospital, who was not concerned within the new examine.

“Within the half-hour earlier than you’re taking your blood strain, you need no smoking, no train, no caffeine, no alcohol, and … no main arguments. Don’t be psychologically careworn,” Adler mentioned.

“Then what you need to do is you need to sit within the chair, get in the suitable place, and for 5 minutes, you loosen up, you don’t speak, you relaxation your arm comfortably, you sit upright together with your again straight, you retain your legs uncrossed and your toes flat on the ground. Be sure to don’t should pee, if it’s a must to pee or urinate, that’s going to lift your blood strain,” she mentioned. “And also you’re not supposed to speak while you take your blood strain, and the cuff needs to be towards your arm. So that you don’t need to put it over garments.”

As a result of individuals typically really feel extra calm and comfy at house, “what we’re discovering now’s research counsel that blood pressures measured at home are a greater indicator of your standard blood strain than blood pressures measured within the workplace,” Adler mentioned.

Blood strain measurements are sometimes “suboptimally carried out” in medical follow, which might result in errors that subsequently and inappropriately alter docs’ selections round managing a affected person’s blood strain in about 20% to 45% of circumstances, based on the American Medical Association.

“Anecdotally, I believe all of us on the examine group have began to pay extra consideration to how our blood pressures are being measured. I’ve definitely paid consideration to how my children’ blood pressures are being measured,” Brady mentioned.

Having hypertension raises the chance for heart disease and stroke, that are main causes of demise in the USA.

It’s estimated that just about half of adults in the USA have hypertension, however solely about 1 in 4 adults with hypertension has their blood strain below management, based on the US Centers for Disease Control and Prevention.

“I don’t assume that we’re aggressive sufficient with the therapy of hypertension in America,” Dr. Dave Montgomery, a heart specialist at Piedmont Healthcare in Atlanta, who was not concerned within the new examine, mentioned in an e-mail.

“Hypertension is among the commonest threat elements for heart problems and among the many best to deal with and management. Nonetheless, hypertension is the offender or main contributor to a big proportion of cardiovascular morbidity and mortality,” he mentioned. “We too typically miss the mark.”

Relating to the brand new examine, he added that he doesn’t see a blood strain studying that could be off by 4 to five mm Hg – as a result of arm place – resulting in overdiagnosis or overtreatment, within the type of a brand new prescription or dose modification.

“If somebody has regular blood strain, 4 mmHg received’t change that. However in somebody with a analysis of hypertension, 5-10 factors might sign that we don’t fairly have the management we search,” Montgomery mentioned. He added that blood strain can change minute by minute, as a result of bodily elements and somebody’s psycho-emotional states.

“Because of this normally we shouldn’t make hasty judgments about one blood strain studying. However constantly hypertension needs to be handled aggressively,” he mentioned. “That is how we decrease the burden of coronary heart illness.”