“Blood pressure is measured incorrectly about half the time,” says physician William B. White, editor of the medical journal Blood Pressure Monitoring.
Here are some common mistakes that can cause your systolic blood pressure reading to be off by 2 to 20 points, according to the American Heart Association and other experts. If you have hypertension, the error is more likely to be at the higher end.
- Don’t have your blood pressure measured after consuming caffeine. Caffeine temporarily raises your pressure.
- Don’t have your blood pressure measured within half an hour of smoking. This can increase blood pressure.
- Don’t get measured if your bladder is full. That can raise your pressure.
- Don’t get measured within 30 minutes of aerobic exercise like brisk walking or jogging. That can lower your pressure temporarily.
- Don’t sit on an exam table or chair with no back support. That can raise your diastolic pressure. (That’s the lower number.)
- Don’t sit with your legs dangling or crossed. That may raise your pressure. Your feet should be flat on the floor.
- Don’t rest your arm above or below your heart level. That can raise or lower your blood pressure. And your upper arm should be supported at heart level by the person taking your blood pressure, not by you.
- Don’t chat with the person doing the measuring. Even a casual conversation can raise your pressure.
- Don’t have the cuff wrapped around clothing. That can lead to a higher reading. So can a cuff that’s too tight (too small for your arm or wrapped too tightly). And a cuff that’s too loose or too large can lead to lower readings.
Before a diagnosis of hypertension (high blood pressure) or prehypertension is made, your blood pressure should be measured at least twice on at least two separate occasions
If you check your pressure at home
The American Heart Association recommends an automatic, cuff-style, bicep (upper-arm) monitor. You should be able to find one for $50 to $100. Wrist and finger monitors give less reliable readings, says the Association.
“You want to make sure that the device you use was independently assessed and validated,” adds Blood Pressure Monitoring editor William B. White.
For a list of validated monitors, see dableducational.org/sphygmomanometers/recommended_cat.html. However, this is not a consumer-friendly list. As an alternative, Consumer Reports rated blood pressure monitors in May 2015.
Tip: To verify your monitor’s accuracy and that you’re using it properly, take it with you to your next doctor’s appointment.
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