Influence of cuff size on the accuracy of supine blood pressure measurement.

Objective: The discrepancy in blood pressure (BP) measurements while in a supine position using an upper-arm automated sphygmomanometer equipped with cuffs of varying sizes remains unresolved.

Methods: In this single-center, randomized crossover trial, a total of 223 inpatients from the Affiliated Hospital of Putian University were enrolled between August and September 2023. Three sets of triplicate BP measurements were obtained while the participants were in a supine position using an automated sphygmomanometer with randomly assigned appropriately sized, undersized, or oversized BP cuffs.

Results: The average age of the subjects was 65.1 ± 18.4 years, with 109 (48.9%) being male and 78 (35%) having coexisting hypertension. Based on the measured mid-arm circumference, a small-sized, regular-sized, and large-sized BP cuff was deemed appropriate for 50, 113, and 60 participants, respectively. In patients requiring small-sized cuffs, the use of regular and large-sized cuffs resulted in a significant reduction in systolic BP by -4.0 [95% confidence interval (CI): -9.8 to 1.9] mmHg and -6.9 (95% CI: -8.0 to -5.8) mmHg, respectively, as well as diastolic BP by -3.4 (95% CI: -8.0 to 1.2) mmHg and -4.1 (95% CI: -5.3 to 2.8) mmHg, respectively. In contrast, among patients requiring large-sized cuffs, the use of small and regular-sized cuffs increased systolic BP by 6.2 (95% CI: 4.2 to 8.2) mmHg and 2.3 (95% CI: -1.4 to 6.1) mmHg, respectively, and diastolic BP increased by 2.6 (95% CI: 1.5 to 3.7) mmHg and 0.2 (95% CI: -4.7 to 5.2) mmHg, respectively.

Conclusion: Our findings suggest that miscuffing affects supine BP measured by an automated sphygmomanometer.