Does size matter?

When it comes to blood pressure (BP) cuffs, size does matter, says an expert.

“Using the regular adult cuff in all individuals showed striking differences in BP,” according to lead author Dr Tammy Brady from the Johns Hopkins University School of Medicine, Baltimore, Maryland, US. “That has a lot of clinical implications.”

Systolic BP readings were on average 3.6 mm Hg lower when a regular adult size cuff was used on participants instead of an appropriate small adult cuff. Meanwhile, in those who required a large adult cuff, systolic readings were 4.8 mm Hg higher with a regular cuff. It was 19.5 mm Hg higher in individuals who are supposed to use an extra-large cuff.

The same was true for diastolic readings.

Brady was reporting findings from the cross-sectional randomized Cuff(SZ) trial at EPI/Lifestyle 2022. [Abstract EP.01]

She said individuals who should be fitted with an extra-large cuff but used a regular cuff instead had an average BP reading of 144/86.7 mm Hg. However, when the correct size cuff was used, their BP went down to an average of 124.5/79.3 mm Hg.

Using too small a cuff misclassified 39 percent of the individuals as being hypertensive, while a cuff that was too large missed 22 percent of those with hypertension.

“Clinicians should have a renewed emphasis on cuff size,” Brady pointed out. “This is specifically relevant in obese patients who require extra-large cuffs … they are most impacted by miscuffing.”

All the participants had 2–3 BP readings taken 30 seconds apart. The BP cuff was either appropriately sized, one size lower, or one size higher, with the sizes randomized.

Half of them had a diagnosis of hypertension based on self-report, a third had a systolic BP of 130 mm Hg or higher, whereas 26 percent had a diastolic BP of 80 mm Hg or higher.

Brady said the recent hypertension guidelines specifically mentioned that if too small a cuff size is used, there would be a difference in BP readings of from 2–11 mm Hg. “In our study, the difference is about from 5 to 20 mm Hg. This is surprising to us clinicians.”

She added that clinics do not routinely stock different cuff sizes and BP monitors sold over the counter typically come with a regular-sized adult cuff.  Worse, some physicians are not the ones measuring their patients’ BP when other healthcare providers may not have access to these data.

This supports the message that cuff size really matters when BP is a concern. “People just don’t realize this,” Brady said.