Systolic BP readings were off by as much as 20 mmHg when using a regular-sized cuff instead of an appropriately small or large cuff.

Clinical practice guidelines emphasise the importance of proper sizing of blood pressure (BP) cuffs (Hypertension 2019; 73: e35-e66), but data on the actual effects of under- or over-cuffing are limited. In this study, investigators recruited 195 community- dwelling adults (mean age, 54 years; mean body mass index, 29 kg/m2; half with hypertension) who underwent random BP determinations with BP cuffs that were too small, too large or appropriate in size. The appropriate cuff size was determined by measuring arm circumference at the midpoint between the acromion and olecranon and using standard manufacturer instructions for a small (20 to 25 cm), regular (25.1 to 32 cm), large (32.1 to 40 cm) or extra-large cuff (40.1 to 55cm). An automated oscillometric device was used.

Results were as follows:

• when a regular cuff was used on a participant for whom a small cuff was appropriate, mean systolic BP was 4 mmHg lower
• when a regular cuff was used on a participant for whom a large or extra-large cuff was appropriate, mean systolic BPs were 5 mmHg and 20 mmHg higher, respectively
• when a cuff that was one or two sizes too large was used, systolic BP was underestimated by about 4 to 9 mmHg
• conversely, when the cuff was one or two sizes too small, BP was overestimated by 4 to 20 mmHg.

Comment: These errors from using inappropriate cuff sizes are clinically important. Resource limitations and time and staffing pressures in many primary care clinics and offices are real, but a relatively quick and easy measurement of arm size and use of a proper BP cuff size could have a substantial influence on clinical decisions for diagnosing and treating hypertension.

Thomas L. Schwenk, MD, Professor Emeritus, Family and Community Medicine, University of Nevada School of Medicine, Reno, USA.

Ishigami J, et al. Effects of cuff size on the accuracy of blood pressure readings: the Cuff(SZ) randomized crossover trial. JAMA Intern Med 2023 Aug 7; e-pub (https://doi.org/10.1001/jamainternmed.2023.3264).

This summary is taken from the following Journal Watch titles: General Medicine, Cardiology, Neurology, Ambulatory Medicine, Hospital Medicine.