Newswise: A study performed by Johns Hopkins Medicine experts reveals that commonly utilized means of positioning the patient’s arm during blood pressure (BP) screenings might greatly overstate test results and may lead to a misinterpretation of hypertension.
Researchers looked at the effects of three distinct arm positions: an arm supported on a desk, an arm supported on a lap, and an unsupported arm hanging at the patient’s side. Their report on the study will be published on October 7 in JAMA Internal Medicine. Researchers discovered that an unsupported arm dangling at the side overestimated systolic pressure by over 7 mmHg, while lap support overestimated systolic pressure—the highest number in a blood pressure reading—by almost 4 mmHg.
Tammy Brady, M.D., Ph.D., vice chair for clinical research in the pediatrics department at Johns Hopkins University School of Medicine, medical director of the pediatric hypertension program at Johns Hopkins Children’s Center, deputy director of the Welch Center for Prevention, Epidemiology, and Clinical Research, and senior author of the study, says the results validate that arm position makes a “huge difference” when it comes to an accurate blood pressure measurement. They underline the need of following to clinical standards calling for firm support on a desk or other surface while monitoring blood pressure, the investigators note.
Read Also: Complementary Therapies Improve Quality of Life in PH
According to the American Heart Association, nearly half of adult Americans have raised blood pressure, which is a measurement of the force of blood flowing through blood vessels that is higher than what is typically considered normal, or 120/80. High blood pressure raises the risk of heart attack, stroke, and other dangerous cardiovascular diseases if left untreated. Early and frequent screening during routine checkups is thought to be the cornerstone of hypertension management because hypertension may generate minimal or no symptoms. In most situations, lifestyle adjustments such as weight loss, good meals and exercise, as well as therapy with any of a variety of drugs, can keep BP under control.
The American Heart Association’s most recent clinical practice guidelines highlight a number of crucial measures to ensure an accurate measurement, such as choosing the right cuff size, providing back support, keeping feet flat on the floor with legs uncrossed, and adopting the right arm position, which involves placing the middle of an adjustable blood pressure cuff at mid-heart level on an arm that is supported by a desk or table.
Despite these recommendations, the researchers say BP is too often measured with patients seated on an exam table without any, or inadequate, arm support. In some cases, a clinician holds the arm, or the patient holds an arm in their lap. In the new Johns Hopkins study, the researchers recruited 133 adult participants (78% Black, 52% female) between Aug. 9, 2022, and June 1, 2023. Study participants, who ranged from age 18 to 80, were sorted at random into one of six possible groups that differed by order of the three seated arm positions. Measurements were taken during a single visit between 9 a.m. and 6 p.m. Before BP measures were taken, all participants first emptied their bladders and then walked for two minutes to mimic a typical clinical scenario in which people walk into a clinic or office before screening takes place. They then underwent a five-minute, seated rest period with their backs and feet supported. Each person, wearing an upper arm BP cuff selected and sized based on their upper arm size, had three sets of triplicate measurements taken with a digital blood pressure device 30 seconds apart.
Upon completion of each round of three measures, the cuff was removed, and participants walked for two minutes and rested for five minutes. They subsequently had a fourth set of triplicate measurements taken during the same visit, this time with their arm resting on a desk. This set of measurements was done to account for known variability in blood pressure readings. Participants were instructed not to speak with researchers or use their phones throughout the screening process, and all measures were done in a quiet, private setting.
Researchers found that BP measurements obtained with arm positions frequently used in clinical practice — an arm on the lap or unsupported at the side — were markedly higher than those obtained when the arm was supported on a desk, the standard, recommended arm position. Supporting the arm on the lap overestimated systolic BP — the top number of readings, or the force of blood flow when pumped out of the heart, by 3.9 mmHg and diastolic blood pressure — the bottom number, or the pressure in the arteries when the heart rests between beats, by 4.0 mmHg. An unsupported arm at the side overestimated systolic by 6.5 mmHg and diastolic by 4.4 mmHg.“Suppose you are consistently measuring blood pressure with an unsupported arm, and that gives you an overestimated BP of 6.5 mmHg. In that case, that’s a potential difference between a systolic BP of 123 and 130, or 133 and 140 — which is considered stage 2 hypertension,” says Sherry Liu, M.H.S., an epidemiology research coordinator at the Welch Center for Prevention, Epidemiology, and Clinical Research, Department of Epidemiology, at Johns Hopkins Bloomberg School of Public Health and study author. Investigators caution that their study results may only apply during screenings with automated BP devices, and may not apply to readings done with other BP devices.
Brady notes that the results do, however, imply that patients “must advocate for themselves in the clinical setting and when measuring their BP at home,” and that physicians should pay more attention to best practice recommendations.
Johns Hopkins writers Di Zhao, Ahmed Sabit, Chathurangi Pathiravasan, Junichi Ishigami, Jeanne Charleston, Edgar Miller III, Kunihiro Matsushita, and Lawrence Appel are among those who have written alongside Brady and Liu.
Resolve to Save Lives—a program backed by Bloomberg Philanthropies, the Bill and Melinda Gates Foundation, and Gates Philanthropy Partners—as well as the Chan Zuckerberg Foundation provided funding for this study.
