Impact of cuff positioning on blood pressure measurement accuracy: may a specially designed cuff make a difference?

Abstract

During blood pressure (BP) measurement, the recommended positioning of the cuff bladder center is directly above the brachial artery. We investigated the relevance of incorrect cuff positioning during (1) auscultatory measurement with an appropriate or improperly small cuff and (2) oscillometric measurement with a wide-range cuff designed to guarantee accurate measurements regardless of position. In subjects with wide BP and arm circumference ranges, (1) auscultatory BP was repeatedly measured with a properly positioned cuff (reference) and, simultaneously, with an identical cuff placed on the other arm in either a correct or an incorrect position (test). The measurements were performed with a properly sized (N=57) or an improperly small cuff (N=33). (2) Auscultatory measurements obtained with a properly positioned and sized cuff were compared with oscillometric measurements obtained with a specially designed wide-range cuff (Omron IntelliWrap) placed on the contralateral arm either in a correct or an incorrect position. Auscultatory BP measures were unaffected by incorrect positioning of a properly sized cuff, whereas with undercuffing, BP was overestimated with the cuff displaced by 90° laterally (systolic/diastolic BP differences: 4.9±4.6/4.0±4.6 mm Hg, P<0.01) or by 180° (3.9±5.4/4.2±5.1 mm Hg, P<0.01) in relation to the correct position. Incorrect placement of the oscillometric cuff had no significant effect on the accuracy of the measurements (difference with correct position <1.5 mm Hg). Incorrect cuff positioning introduces a systematic overestimation of auscultatory BP when the cuff is too small in relation to arm circumference but not when it is correctly sized. No systematic error was observed with oscillometric measurements obtained with a specially designed wide-range cuff.