Effect of an upper-arm constricting device on arm blood pressure measurements

Thousands of blood pressure measurements are done daily without the patients' disrobing. This study was therefore undertaken to determine the validity of such measurements, especially those taken when the patient's armsleeve has been rolled up onto the proximal aspect of the arm. An inflatable constricting device was applied to the proximal aspect of the arm and a standard sphygmomanometer was applied distal to the inflatable cuff. The constricting cuff was inflated to 0, 20, 40, 60, 80, and 100 mm Hg in random sequence, and the blood pressure was recorded at each level. Statistically significant elevations in the mean systolic blood pressure were detected at proximal constricting pressures of 80 mm Hg (P less than .01) and 100 mm Hg (P less than .001), and in the mean diastolic blood pressure at 20 mm Hg (P less than .005). However, the magnitude of the elevations was small: 3.9, 4.4, and 2.5 mm Hg, respectively. We conclude that though a proximal constricting device may induce statistically significant alterations in blood pressure measurements these alterations are small and not likely to affect treatment decisions.