ANKLE BLOOD-PRESSURE MEASUREMENT, AN ACCEPTABLE ALTERNATIVE TO ARM MEASUREMENTS

The use of automatic noninvasive blood pressure (NIBP) devices has bec ome a common technique to monitor blood pressure intraoperatively. The usual cuff placement for these devices on the upper arm sometimes pos es problems. As an alternative, many clinicians place the cuff on the ankle. This practice has not been previously investigated to determine its efficacy. The purpose of our study was to determine whether a non invasive blood pressure cuff on the arm could be replaced by one on th e ankle. We monitored 24 patients intraoperatively with two non-invasi ve blood pressure cuffs, one on the upper arm and one on the ankle. Sy stolic, diastolic, and mean pressures were obtained from each cuff pla cement at intervals of no shorter than 3 minutes. The time necessary t o obtain the measurements and the presence of any artifact were also r ecorded. A total of 404 pairs of data were obtained and the systolic b lood pressure ranged from 82 to 196 mm Hg. The mean and diastolic pres sure readings were equivalent between the arm and ankle blood pressure readings. The systolic pressures were not equivalent, reflecting the fact that the ankle systolic blood pressure is physiologically higher than the arm systolic blood pressure. The difference between the times necessary to obtain the readings from arm or ankle was not statistica lly significant. Eight of the paired readings (2.0%) represented artif act, arbitrarily defined as a difference in mean blood pressure readin gs of 15 mm Hg between the arm and the ankle. Since the mean blood pre ssure readings obtained at the arm and at the ankle were statistically equivalent, we concluded that the ankle cuff placement provided a rel iable alternative to the placement of the cuff on the arm.