Blood pressure measurement in adults: large cuffs for all?

STUDY OBJECTIVE The aim of the study was to determine whether a single size of cuff for adult blood pressure measurements is appropriate for general clinical practice. DESIGN The study was a prospective survey of a sample of adult blood pressure measurements using two cuffs with different bladder sizes (12 X 23 cm and 15 X 33 cm) in a randomised design using a random zero sphygmomanometer. SETTING Blood pressures were measured in a general practice and in a hospital outpatient clinic. PARTICIPANTS The participants were 35-60 year old men and women invited to attend a blood pressure screening programme in the general practice (n = 170), and 35-74 year old patients attending a general medical outpatients (n = 72). MEASUREMENTS AND MAIN RESULTS The small cuff gave higher readings of systolic blood pressure than the large cuff (mean difference 4.4 mm Hg). The difference increased as systolic pressure increased but did not show a clear association with arm circumference. The small cuff also gave higher diastolic pressure readings (mean difference 3.0 mm Hg), but only when arm circumference exceeded 30 cm. The variability of the differences between readings from the two cuffs was wide, little affected by arm circumference, and was similar to the variability between measurements using the same cuff size. CONCLUSIONS In terms of precision there is no basis for using two different cuff sizes unless it is physically difficult to obtain a reading with one or the other. Since readings with large cuffs are closer to intraarterial pressures in large arms, and the large cuff used here did not underestimate diastolic pressure in small arms, the large cuff alone could be recommended for general use.