Everybody loves to get something for nothing. But one particular freebie – the blood pressure machines found in pharmacies, supermarkets, and other public places – may be hazardous to your health because they often give false readings, say experts.
The main problem is the one-size-doesn’t-fit-all arm cuffs. If the cuff is too small, you’ll get an artificially high reading. If it’s too big, you’ll get a falsely low reading.
But even if you have an arm that correctly fits the machine, you may still get an inaccurate reading.
The reason: public machines get a lot of use. Unless they’re tested twice a year and recalibrated if necessary – which most aren’t – they will give inaccurate results.
“People need to realize that there are limitations,” says Mary Ann Bauman, M.D., national spokesperson for the American Heart Association. “That’s why it’s worthwhile to be cautious about those readings.”
One recent study from the Mayo Clinic shows that in-store machines are more accurate for people with average-size arms than for those with small or large-size arms.
Other studies show that such machines tend to underestimate blood pressure, especially systolic pressure (the top number). Normal blood pressure is considered 120/80 or lower, prehypertension is 120-139/80-89, and high blood pressure or hypertension is defined as 140/90 or higher.
Nearly one in three U.S. adults has hypertension, a condition that often shows no symptoms. Uncontrolled hypertension increases the risk of heart attack, strokes, heart failure, kidney failure, and death.
Instead of relying on a free blood pressure machine, Dr. Bauman recommends investing $30 to $70 on a home monitor, which will give you more accurate readings.
“Use one with an upper-arm cuff,” she tells Newsmax Health. “The ones with wrist or finger cuffs are not accurate.”
In general, you should measure blood pressure in your non-dominant arm. If you find that the pressure is consistently greater in your dominant arm, however, you should use that arm instead.
Here are tips from the AHA to ensure accurate readings:
• Make sure the cuff fits. Measure the circumference of your upper arm and choose a monitor with a correct-size cuff.
• Be still. Don’t smoke, drink caffeinated beverages, or exercise within 30 minutes of measuring your blood pressure.
• Sit correctly. Sit with your back straight and supported and your feet flat on the floor. Don’t cross your legs or ankles. Support your arm on a flat surface with the upper arm at heart level.
• Take multiple readings. Take two or three readings one minute apart and record all the results.
• Measure at the same time daily. It’s important to take the readings at the same time each day, such as morning and evening, or as your healthcare professional recommends.
• Record all your results. Record all of your readings, including the date and time taken. Share your blood pressure records with your healthcare team. Some monitors have built-in memory to store your readings. Some monitors may also allow you to upload your readings to a Website. Another good way to save your readings is to use a phone app. Blood Pressure Companion, which costs 99 cents, is a popular one. It charts your readings, allowing your doctor to see trends regarding your blood pressure.
(We thank health reporter Rick Ansorge for the valuable article)
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