Clinical Question

To what extent does the wrong cuff size affect blood pressure readings?

Bottom Line

The study found that using a regular cuff on arms that are larger than average can falsely raise blood pressure readings by almost 5 mm Hg, and a regular cuff on an especially thin arm can lower readings by 3.6 mm Hg. More than one-half of the study group, which had a mean body mass index lower than the U.S. average, required a large or extra-large cuff. (Level of Evidence = 1b)

Synopsis

The researchers recruited 195 participants from the community and hypertension clinics. Each participant (mean body mass index = 28.8 kg per m²) underwent four sets of triplicate automated blood pressure measurements with an appropriately sized, too small, or too large blood pressure cuff in random order, followed by a fourth set of triplicate measurements using an appropriately sized cuff only. The cuff size was based on the mid-upper arm circumference and matched to the appropriately labeled cuff. Only 28% of the participants in this sample were the right size for a regular cuff, and more than one-half (55%) required a large or extra-large cuff. Participants who required a large cuff had systolic readings that were 4.8 mm Hg (95% CI, 3.0 to 6.6) higher, on average, when a regular-sized cuff was used. Participants with small arms showed a reduced systolic pressure by 3.6 mm Hg (95% CI, −5.6 to −1.7), on average, with a regular-sized cuff.