Effect of clothing on sphygmomanometric and oscillometric blood pressure measurement in hypertensive subjects

Background and objective: The few studies published on this subject have shown that blood pressure measurements give similar results whether the patients' arm is covered by clothing or not. But it has not been clarified whether this is also true in the case of hypertensive persons, Yet, in practice the correct measurement is of critical importance in the diagnosis of hypertension. Methods: 203 hypertensive patients were examined with the auscultatory sphygmomanometry and the automatic oscillometry by measuring the pressure three times with each method. These tests were carried out in a randomized sequence on a covered arm (the patient's own clothing of maximally 2 mm thickness), the bare arm and the arm covered with a standardized cotton sleeve (2 mm). The auscultatory sphygmomanometry was done blinded (non-sleeved, sleeved, standardized). Results: Calculation of confidence intervals for the mean differences of the three settings (bare, clothing and standard sleeve) and equivalence testing demonstrated that a garment or cloth on the arm under the manometer cuffs did not significantly effect the blood pressure within the predefined interval of equivalence of 4 mm Hg. Thus, measuring blood pressure with the cuff over the person's sleeve does not significantly effect the result. Conclusion: This study shows that measuring blood pressure in hypertensive persons with or without a cloth sleeve (maximally 2 mm thick) does not result in any statistically significant difference. This simplifies the blood pressure measurement that have to be taken frequently on hypertensive persons.