A new study conducted by researchers at Johns Hopkins Medicine explored the ways that different arm positions during blood pressure readings can affect the outcome.
According to their findings, three of the most common arm positions used during blood pressure (BP) readings can lead to higher results than others.
“We demonstrate that when the arm is completely unsupported and hanging at the side, as is often the case when arm support on a desk or chair is not possible, or when a patient is seated on the examination table in a clinic room, BP is greatly overestimated,” the researchers wrote.
“Furthermore, positioning the arm in the lap, a typical compromise for the above scenarios, also results in considerable BP overestimation. Thus, these arm positions should not be used, even in the setting of limited time or resources. Proper arm position may be even more important for individuals at higher risk for cardiovascular disease, particularly those with hypertensive systolic blood pressure.”
Identifying the discrepancies
For the study, 133 participants between the ages of 18 and 80 were recruited, and they tested out various arm positions during blood pressure readings.
The researchers were most interested in looking at three of the most common arm positions for BP readings: the arm supported on a desk, the hand supported on the lap, and an unsupported arm hanging at the person’s side. The participants then had a fourth test with their arm supported on a desk as a final check for any potential variability between the readings.
Each participant had three sets of measurements taken with a blood pressure device, with each one taken 30 seconds apart.
Ultimately, the researchers learned that when participants had an arm on their lap or unsupported at their side, their BP readings were higher. However, when the arm was supported on a desk, which is the recommended way to conduct a BP reading, the reading was lower.
Which arm positions should be used?
Having an unsupported arm at the side yielded the highest BP readings. When participants were positioned this way, their systolic BP, or the top number of the reading, was 6.5 mmHg higher, and their diastolic BP, or the bottom number of the reading, was 4.4 mmHg higher.
For those with hypertension, systolic blood pressure was 9 mmHg higher when the arm was positioned this way.
Similarly, when participants rested their arms on their laps, their systolic BP was 3.9 mmHg higher, and their diastolic BP was 4.0 mmHg higher.
“If you are consistently measuring blood pressure with an unsupported arm, and that gives you an overestimated BP of 6.5 mmHg, that’s a potential difference between a systolic BP of 123 and 130, or 133 and 140 — which is considered stage 2 hypertension,” said researcher Sherry Liu, M.H.S.
The researchers suggest that consumers advocate for themselves during their next BP reading. Many health care providers may not be aware of these discrepancies in BP readings, and to avoid incorrect diagnoses, it’s crucial to get the most accurate reading.