The effect of clothes on sphygmomanometric and oscillometric blood pressure measurement

Abstract

Aim: We determined the effect of wearing clothes under the manometer's cuff on blood pressure in manual auscultatory sphygmomanometric and automatic oscillometric blood pressure measurement. Methods: Two hundred and one subjects were examined with the auscultatory sphygmomanometric and the automatic oscillometric method, each with and without sleeved arm in random order. The auscultatory readings were blinded for the subjects' state of clothing. Common shirts and sweaters (thinner than 2 mm) were used. Results: Based on confidence intervals of the differences between sleeved and non-sleeved arm measurements and equivalence test, sleeves did not lead to statistically significant effects. Measurements with and without sleeve can be accepted equal within an a priori defined interval of equivalence of ±4 mmHg. Discussion: This study shows that measuring blood pressure with the manometer's cuff over the subject's sleeve does not differ significantly from non-sleeved arm measurements. This is true for a sample that includes normotensive as well as hypertensive persons with a wide age range. For clinical practice, the not significant mean differences of 0.5-1.1 mmHg are interpreted as not relevant. In this study with a statistical power to find a difference of 4 mmHg, blood pressure measurements were found to be equivalent with and without clothes thinner than 2 mm.