“Striking” differences in BP when using the wrong cuff size
Strong new evidence on the need to use an appropriately sized cuff for blood pressure (BP) measurement comes from the randomized cross-sectional Cuff(SZ) trial.
The study found that in people for whom a small adult cuff was appropriate, systolic BP readings were on average 3.6 mm Hg lower when a regular adult sized cuff was used.
However, systolic readings were on average 4.8 mm Hg higher when a regular cuff was used in people who needed a large adult cuff and 19.5 mm Hg higher in those who needed an extra-large cuff based on their mid-arm circumference.
Diastolic readings followed a similar pattern (-1.3 mm Hg, 1.8 mm Hg, 7.4 mm Hg, respectively).
“We found that using the regular adult cuff in all individuals showed striking differences in blood pressure,” said lead author Tammy M. Brady, MD, PhD, Johns Hopkins University School of Medicine, Baltimore, Maryland . lecoeur.org | Medscape Cardiology. “And that has a lot of clinical implications.”
She noted, for example, that people who needed an extra-large cuff and were measured with a regular cuff had an average BP of 144/86.7 mm Hg, which is within the range of stage 2 hypertension. But when the correct size cuff was used, the average BP was 124.5/79.3 mm Hg, or in the prehypertensive range.
Overall, overestimation of BP due to use of too small a cuff incorrectly classified 39% of people as having hypertension, while underestimation of BP due to use of a too large cuff missed 22% of people with hypertension.
“So I think clinicians really need to put a renewed emphasis on cuff sizing, especially in populations where obesity is prevalent and where many of their patients need extra-large cuffs, because those are the populations most affected by a bad armband,” Brady mentioned.
The findings were presented in an electronic poster today at the Epidemiology and Prevention/Lifestyle and Cardiometabolic Health (EPI/Lifestyle) 2022 conference sponsored by the American Heart Association (AHA).
Willie Lawrence, MD, chair of the AHA’s National Hypertension Control Initiative Advisory Committee, said in an interview that the extent of the inaccuracy observed by the researchers “makes this a very, very study.” important”.
“Is this the first of its kind, no, but it’s incredibly important because it’s been done so well and it comes at a time when people are again facing equity issues and this study can have a significant impact on the state of hypertension in various communities,” said Lawrence, cardiologist at Spectrum Health Lakeland in Benton Harbor, Michigan.
Previous studies examining the issue were older, had few participants, and used mercury sphygmomanometers instead of automated devices, which are generally recommended by professional societies for screening adults for hypertension, Brady explained.
For the Cuff Size Blood Pressure Measurement trial, 195 community-recruited adults underwent 2-3 sets of 3 BP readings, 30 seconds apart, with an automated, validated device (Welch Allyn ProB 2000) using a cuff appropriately sized TA, one size down and one size up. The order of cuff sizes was randomized. Prior to each series, patients walked for 2 minutes followed by 5 minutes of rest to eliminate the potential effect of longer rest periods between tests on results. The room was also kept quiet and attendees were asked not to talk or use a smart phone.
Participants had an average age of 54 years, 34% were male, 68% were black, and 36% had a body mass index of at least 30 kg/m2meet the criteria for obesity.
About half had a diagnosis of self-reported hypertension, 31% had a systolic BP of 130 mm Hg or higher, and 26% had a diastolic BP of 80 mm Hg or higher.
Based on upper arm circumference (average, 34 cm), appropriate adult cuff size was small (20 – 25 cm) in 18%, regular (25.1 – 32 cm) in 28%, large (32.1 – 40 cm) in 34%, and extra-large (40.1 – 55 cm) in 21%.
Brady pointed out that the most recent hypertension guidelines detail the sources of inaccuracy in blood pressure measurement and indicate that if too small a cuff size is used, blood pressure could be 2-11mm different. Hg.” And what we’re showing is that it can go anywhere from 5 to 20 mm Hg. So I think that’s a significant difference from what studies have shown so far and it’s going be very surprising to clinicians.”
A 2019 AHA science statement on blood pressure measurement highlights the importance of cuff size, and last year the American Medical Association launched a new initiative to standardize measurement training. blood pressure for future doctors and health professionals.
Previous work has also shown that children as young as 3 to 5 years old often need an adult cuff size and those in the 12 to 15 year age range may need an extra-large cuff. wide, or what is often called a thigh. cuff, said Brady, who is also the medical director of the pediatric hypertension program at Johns Hopkins Children’s Center.
“Part of the problem is that many physicians are not often the ones doing the measurement and others may not be as in tune with some of this data and initiatives,” she said.
Other barriers are cost and availability. Offices and clinics don’t routinely stock multiple cuff sizes in exam rooms, and devices sold over the counter usually come with a regular adult cuff, Brady said. An extra cuff could add $25 to $50 on top of the device’s $25 to $50 for the growing number of patients measuring blood pressure remotely.
“During the pandemic, I was trying to do telemedicine with my hypertensive patients, but the children who were significantly obese couldn’t afford or find blood pressure measuring devices with a cuff big enough for them” , she said. “It just wasn’t something they could get. So I think people just don’t realize how important that is.”
PPE/Lifestyle 2022. Summary EP01. Presented March 1, 2022.
The study was funded by Resolve to Save Lives, which is funded by the Bill and Melinda Gates Foundation and Gates Philanthropy. Brady and Lawrence say they have no relevant financial relationship.