Researchers have found that improper arm positioning can affect the accuracy of blood pressure readings.
The study is significant because variations in readings may result in an increased number of high blood pressure diagnoses and the prescription of unnecessary medications to patients.
Let’s take a closer look.
What does the study say?
Researchers at Johns Hopkins Medicine in the United States examined blood pressure measurements in three different scenarios: the patient’s arms hanging at their side, supported on a desk, and supported on a lap.
A total of 133 people between the ages of 18 and 80 were chosen for the study, and each participant’s blood pressure was measured in a single visit.
Before readings were obtained, all participants emptied their bladders, walked for two minutes to simulate somebody going to the clinic, and then sat down and rested for five minutes with their backs and feet supported.
A digital blood pressure monitor was used to take readings every 30 seconds while each participant wore an upper-arm blood pressure cuff that fit their arm.
According to the findings, which were published in the journal JAMA Internal Medicine, a person’s arm posture may have a significant impact on their blood pressure measurements; an arm hung at the side produced the highest readings.
How much is the difference?
Study senior author Dr Tammy Brady said arm position makes a “huge difference” when it comes to an accurate blood pressure measurement and people should always have their arm on firm support such as a desk or table.
“The size of the difference, nearly seven points in the arm dangling position, was a surprise,” she said.
They found that certain arm postures, such as placing the arm on a person’s lap, might significantly exaggerate blood pressure readings.
The study showed that placing one arm on the lap increased blood pressure readings by 3.9 mmHg for the systolic (top number) and 4 mmHg for the diastolic (bottom number).
While systolic refers to the amount of pressure in a person’s arteries when the heart sends blood throughout the body, diastolic is the pressure in the arteries between heartbeats.
A hanging arm that was not supported overstated the systolic pressure by 6.5 mmHg and diastolic pressure by 4.4 mmHg.
Prior to conducting their experiment, the researchers were unsure of what to anticipate. “There was a chance that arm position was not important,” she said.
“One of my hopes is that this will help inform patients as to how to do this on their own and also to tell their health care provider the right way,” Brady said. “Patients should be empowered to make sure the blood pressure measurement is accurate.”
What do other experts say?
Dr Karyn Singer, an assistant professor of medicine at New York University, told NBC News, “Mispositioning of a patient’s arm unfortunately is a common experience. As a patient, I’ve been there,” adding that the study provides a “piece of evidence that is really critical.” “Until now, it hasn’t been clear how much arm position changes blood pressure readings.”
UCLA Health cardiologist Dr Megan Kamath also agreed, saying, “There is a pretty significant difference in blood pressure readings depending on arm position.”
“This is a fascinating study. What I took from reading it was, wow, with a simple study design these researchers found some important real world implications that can make the difference between a patient being treated for hypertension or not,” she told the outlet.
Dr Matthew Tomey, a cardiologist at Mount Sinai Fuster Heart Hospital, said that the study supports a patient asking for a doctor to measure blood pressure the “right way.”
Cardiologist at Piedmont Healthcare in Atlanta, Dr Dave Montgomery, doesn’t believe that blood pressure readings that may be off by 4 to 5 mmHg due to arm position lead to overdiagnosis or overtreatment in the form of a new prescription or dose modification.
He told CNN that a person’s psycho-emotional and physical conditions might cause blood pressure to fluctuate minute by minute.
“This means that in general, we shouldn’t make hasty judgments about one blood pressure reading. But consistently high blood pressure should be treated aggressively,” he said. “This is how we lower the burden of heart disease.”
What are the guidelines to get an accurate reading?
The UK-based National Health Services advises that correct positioning is to sit on an upright chair with a back, placing both feet flat on the floor and resting the arm on a table or desk.
People should also rest for five minutes before taking a reading and then take another reading several minutes later to check it is accurate.
Avoid caffeine, exercise and smoking for 30 minutes.
The blood pressure cuff should be positioned at mid-heart level.
What’s the ideal blood pressure?
The NHS advises that normal blood pressure is between 90/60 mmHg and 120/80 mmHg.
High blood pressure or hypertension is considered to be 135/85 or higher if the reading was taken at home, or 140/90 mmHg or higher if the reading was taken at a pharmacy, GP surgery or clinic.
It affects nearly one billion people globally, as per the World Heart Federation. In India, more than one person in every four people has hypertension, which occurs when the measured force of blood flowing through blood vessels is higher than what is considered normal. In the US, nearly half of American adults have high blood pressure.
Hypertension often causes minimal symptoms. However, if it is untreated, it can increase the risk of stroke, heart attack and other serious cardiovascular conditions.
With inputs from agencies
