Common arm position can significantly overestimate blood pressure readings, Johns Hopkins study finds

Research led johns hopkins medicine Researchers conclude that the common method of positioning a patient's arm during blood pressure (BP) screening can significantly overestimate test results and may lead to misdiagnosis of hypertension. .

in research reportreleased on October 7th. JAMA Internal MedicineThe researchers looked at the effects of three different arm positions: supporting the arm on a desk, supporting the arm in the lap, and letting the unsupported arm hang by the patient's side. Researchers found that wrap support overestimated systolic blood pressure (the highest blood pressure reading) by nearly 4 mmHg, and lying with the unsupported arm in a lateral position overestimated systolic blood pressure by nearly 7 mmHg. I discovered.

Image caption: Tammy Brady

image credit: Johns Hopkins Medicine

The study says the results confirm that arm position makes a “huge difference” when it comes to accurately measuring blood pressure. Tammy BradyVice Chair for Pediatric Clinical Research and Medical Director of the Pediatric Hypertension Program, Johns Hopkins University School of Medicine Johns Hopkins Children's CenterDeputy Director Welch Center for Prevention, Epidemiology, and Clinical Researchsenior author of the study. It also emphasizes the importance of adhering to clinical guidelines that call for firm support on a desk or other surface when measuring blood pressure.

According to the American Heart Association, nearly half of adults in the United States have high blood pressure, which is diagnosed when a measurement of the force of blood flowing through blood vessels is higher than what is generally considered normal (120/80 on average). Untreated high blood pressure increases your risk of stroke, heart attack, and other serious cardiovascular diseases. Because high blood pressure may have few or no symptoms, early and frequent screening during routine checkups is considered the cornerstone of high blood pressure management. In most cases, blood pressure can be controlled through lifestyle changes such as weight loss, healthy eating, exercise, and various medications.

The American Heart Association's latest clinical practice guidelines highlight several important steps for accurate measurements. Appropriate cuff sizeback support, feet flat on the floor without legs crossed, and proper arm position with the center of the adjustable blood pressure cuff located at mid-heart level on the arm supported on a desk or table.

Despite these recommendations, researchers say blood pressure is too often measured in patients seated on an examination table with no or insufficient arm support. In some cases, the clinician may hold the arm or the patient may hold the arm in the lap. In the new Johns Hopkins study, researchers recruited 133 adult participants (78% Black and 52% female) between August 9, 2022 and June 1, 2023. Study participants, ranging in age from 18 to 80 years, were randomly categorized into one of six possible groups depending on the order of the three seated arm positions. Measurements were taken during a single visit from 9:00 a.m. to 6:00 p.m. Before taking blood pressure measurements, all participants first emptied their bladders and then walked for 2 minutes before the screening took place. simulated a typical clinical scenario of entering a laboratory or office. . I then took a 5-minute break while sitting with my back and legs supported. Each person wore a brachial blood pressure cuff selected and sized based on their upper arm size and took three sets of three measurements at 30-second intervals using a digital blood pressure device.

The researchers found that blood pressure measurements obtained in arm positions frequently used in clinical settings (arm resting on the lap or not supported at the side) were obtained with the arm supported on a desk. found that it was significantly higher than the case.

After each set of three measurements was completed, the cuff was removed and participants walked for 2 minutes and rested for 5 minutes. At the same visit, they underwent a fourth triple measurement with their arms propped up on a desk. This set was used to account for well-known variations in blood pressure measurements. All measurements were taken in a quiet, private space, and participants were asked not to talk to researchers or use their mobile phones during the screening.

The researchers found that blood pressure measurements taken in arm positions frequently used in clinical settings (arm resting on the knee or not supported at the side) were lower than the standard recommended arm position. They found that the blood pressure values ​​were significantly higher than those obtained when the arm was propped up on a desk. Propping your arms on your knees overestimates your systolic blood pressure (the upper limit of your reading, or the force of your blood as it leaves your heart) by 3.9 mmHg, and overestimates your diastolic blood pressure (your lower limit, or pressure inside the artery as it is pumped out) was overestimated. the heart rests between beats) decreases by 4.0 mmHg. Without side arm support, systole was overestimated by 6.5 mmHg and diastole by 4.4 mmHg.

“If you are constantly measuring your blood pressure in your unsupported arm and your blood pressure is overestimated by 6.5 mmHg, this means there is a potential difference between your systolic blood pressures of 123 and 130 or 133 and 140. “This is considered stage 2 hypertension,” said Shelley Liu, epidemiology research coordinator in the Welch Center for Prevention, Epidemiology, and Clinical Research in the Department of Epidemiology. Johns Hopkins University Bloomberg School of Public Health and study author.

Researchers cautioned that the study results may only apply during screening using automated blood pressure devices and may not apply to measurements taken using other blood pressure devices. I am.

Image caption: A collage of arm positions studied by researchers. The study says the findings highlight the importance of following clinical guidelines, which call for firmly supporting the arm on a surface such as a desk when measuring blood pressure.

image credit: Johns Hopkins Medicine

But Brady said the study's findings mean clinicians need to pay more attention to best practice guidelines and that patients “need to be more assertive when measuring their blood pressure in the clinic or at home.” ” suggests that.

In addition to Brady and Liu, authors from Johns Hopkins University include: Di Zhao, Ahmed Savit, Chaturangi Pathiravasan, Junichi Ishigami, jeanne charleston, edgar miller iii, Kunihiro Matsushitaand Lawrence Appel.

This research was supported by Resolve to Save Lives, a project funded by Gates Philanthropies Partners with support from Bloomberg Philanthropies, the Bill and Melinda Gates Foundation, and the Chan Zuckerberg Foundation. The Johns Hopkins authors declare that they have no conflicts of interest.