Wrong-sized blood pressure cuffs give inaccurate results, trial finds
Using a regular-sized blood pressure cuff led to inaccurately low systolic readings in patients who should have been measured with a small cuff and overly high readings in those who should have been measured with a large or extra-large cuff.
A new study showed the importance of using an appropriately sized cuff when measuring blood pressure (BP).
The randomized crossover trial included 195 community-dwelling adults (51% with hypertension) with a wide range of mid-arm circumferences in Baltimore. All underwent four sets of triplicate BP measurements with an automated device; the initial three sets used an appropriate, too-small, or too-large BP cuff in random order, and the fourth set of measurements was always completed with an appropriately sized BP cuff based on mid-arm circumference. Results were published by JAMA Internal Medicine on Aug. 7.
In those who should have been measured with a small BP cuff, use of a regular cuff resulted in a significantly lower BP reading (mean systolic difference, −3.6 mm Hg; 95% CI, −5.6 to −1.7 mm Hg). Using a regular cuff in those who required a large or extra-large BP cuff resulted in a significantly higher systolic reading (mean difference, 4.8 mm Hg [95% CI, 3.0 to 6.6 mm Hg] and 19.5 mm Hg [95% CI, 16.1 to 22.9 mm Hg], respectively). The study found that differences from cuffs that were one and two sizes too big or too small were greater among those requiring larger cuffs. The results were consistent in analyses stratified by systolic BP and body mass index.
The results show that use of a cuff of the wrong size can lead to “strikingly inaccurate BP measurements,” said the study authors. “Published studies have demonstrated that individualized cuff selection does not commonly occur in clinic settings,” they reported, adding that a study of medical students found they chose the wrong size a quarter of the time.
“This study is timely, considering that automated digital BP monitors are increasingly used in inpatient and outpatient settings, with clinical guidelines recommending these devices,” said an accompanying editorial. “These findings emphasize the need for increased availability of a wide variety of BP cuff sizes in clinics and hospitals.”