Cuff Size Important for Blood Pressure Readings - Healthline

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The correct cuff size can help people who monitor their blood pressure from home. Siro Rodenas Cortes/Getty Images

• Researchers report that an incorrect cuff size on blood pressure monitoring devices can provide inaccurate readings.
• This can result in unnecessary medication prescriptions as well as lack of treatment.
• The issue can affect people who get their blood pressure checked at a doctor's office as well as someone who takes their own readings at home.

If you think one-size-fits-all doesn't work very well in clothing, scientists want you to know that it doesn't work when it comes to your blood pressure readings.

They say a wrong cuff size could get you a false reading.

That means your doctor might prescribe too much or too little medication for you. It could also mean your high blood pressure goes untreated.

That's the preliminary conclusion of a new study released March 1 during the American Heart Association's Epidemiology, Prevention, Lifestyle & Cardiometabolic Health Conference 2022 in Chicago.

The information could be important for millions of people, especially those who take their blood pressure readings at home.

A 2017 study found that nearly half of adults in the United States have high blood pressure (hypertension). That's defined by the top or systolic number being 130 mm Hg or greater and the diastolic or bottom number being 80 mm Hg or higher.

In addition, in 2019, more than half a million deaths in the United States had hypertension as a primary or contributing cause.

The authors of the new study say what's different about their findings is that researchers used automatic blood pressure measuring devices, the kind you often find in your doctor's office, or you may be using at home.

"It has even more implications for people who want to do blood pressure monitoring at home. Blood pressure devices you purchase at a pharmacy or online come with one cuff size. And many people don't realize how important it is to get a cuff size that's the right size for your arm," said Dr. Tammy McLoughlin Brady, vice chair for clinical research in the Department of Pediatrics at the Johns Hopkins University School of Medicine in Maryland as well as the medical director of the Pediatric Hypertension Program at the Johns Hopkins Children's Center.

"If you need an extra-large cuff, you would need to find select devices because they don't come with an extra-large cuff, or you have to pay almost twice the amount to get an extra-large cuff to fit your arm," Brady told Healthline.

The study researchers analyzed blood pressure readings of 165 adults in Baltimore. In a single setting, they compared the average of three readings using a regular adult-sized cuff versus the readings from a cuff appropriately sized for their arms.

They found that the individuals who needed an extra-large cuff had a reading of 143/86 when a regular-sized cuff was used. That reading falls in the range of the diagnosis of stage two hypertension.

However, with an appropriately sized cuff, that reading averaged 124/79, which is in the standard range.

"In our study, the overestimation of blood pressure due to using a cuff that is too small misclassified 39 percent of participants as being hypertensive," Brady said. "While the underestimation of blood pressure due to using a cuff that is too large missed 22 percent of participants with hypertension."

The American Heart Association recommends using a tape measure around the bicep at mid-arm to get the right measurements.

Then compare those numbers against their chart to find what size cuff you should be using.

Brady also says the device you're using should have been tested and approved for accuracy. You can check for a list of those devices at https://www.validatebp.org/ or https://www.stridebp.org/.

There are also steps you need to follow before and while you are measuring your blood pressure.

Here are 10 tips to get a more accurate reading:

• Use the right size cuff.
• Don't put the cuff over your clothing.
• Relax for 3 to 5 minutes before taking your reading.
• Sit in a comfortable chair. Don't dangle your feet, be sure to uncross your legs, and make sure your back and arm are supported.
• Try not to be tense or stressed.
• Don't talk during your reading.
• Don't smoke for at least 30 minutes before.
• Avoid alcohol and caffeine for at least 30 minutes before.
• Don't sit in a cold room. Being in the cold could increase your blood pressure reading.
• Go to the bathroom before. A full bladder increases your blood pressure.

Brady says the findings help physicians, too.

A doctor might start a patient diagnosed with stage two hypertension on two blood pressure medications. So getting the right readings is key.

"I think this is super-important for providers who have a large population of patients with comorbid obesity because they are the ones who are going to be most impacted by incorrect measurement," she said.

"I hope this brings about awareness about how important this is," she added. "And I hope patients feel empowered to ask their providers, 'Is this the right cuff for me?'"

Dr. Anna Svatikova, an assistant professor of medicine in preventive cardiology at the Mayo Clinic in Minnesota, calls the research important.

"This study brings public awareness of the importance of blood pressure cuff size when measuring blood pressure at home, in the healthcare setting, or in public kiosks," she told Healthline.

"Hypertension is a major risk factor for development of heart disease and stroke. It is the leading cause of death globally," she added.