A new study from Johns Hopkins Medicine has found that the way your arm is positioned during a blood pressure check can strongly affect the results.
Even small changes in how your arm rests can make your blood pressure seem higher than it really is. This might cause doctors to wrongly say you have high blood pressure when you don’t.
The researchers looked at three common ways people place their arms during a check: resting on a desk, resting on their lap, and letting the arm hang down at the side. They found that when the arm was on the lap, the top number—called systolic pressure—was almost 4 points higher. When the arm hung by the side, it was nearly 7 points too high.
That difference may sound small, but it matters. According to the American Heart Association, a systolic reading of 130 or higher is considered stage 2 high blood pressure. So if your reading is wrong by just a few points, you could be misdiagnosed and put on unnecessary medicine.
Blood pressure checks are important because high blood pressure often has no symptoms but can lead to serious problems like heart attacks and strokes. Most people can manage it with healthy habits like eating well, moving more, and taking medicine if needed.
Doctors say the correct way to measure blood pressure is to sit with your back supported, your feet flat on the floor, and your arm resting on a table at the same height as your heart. But in real life, this isn’t always followed.
Often, people sit on exam tables without back or foot support. They might put their arm in their lap or let it hang at their side. Sometimes, a nurse or doctor might hold their arm up instead. All these ways can give the wrong numbers.
In this study, researchers worked with 133 adults from different backgrounds. They checked blood pressure in all three arm positions during one visit. Before each test, people walked for two minutes, like they would before seeing a doctor. Then they sat and had their blood pressure taken three times using a digital machine.
The results were clear. The best readings came when the arm was supported on a desk. The other two positions gave higher numbers. On average, both the top and bottom numbers were about 4 to 7 points too high. That’s enough to wrongly label someone as having high blood pressure.
This study shows that how blood pressure is taken really matters. It also reminds us that even small mistakes can lead to big changes in health care.
Although this study used digital machines, the message is still important. Health workers should follow the correct steps. And if you’re getting your blood pressure checked, don’t be afraid to ask if it’s being done the right way.
If you check your blood pressure at home, sit properly with your back supported, your feet on the floor, and your arm resting at heart level. A simple change in arm position could make a big difference in your health.
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The study was published in the journal Cerebral Circulation – Cognition and Behavior.
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