Digital Blood Pressure in Patients with Peripheral Arterial Disease Reproducibility and Influence of Change in Posture

Abstract

Reproducibility of indirect measurements of systolic blood pressure at ankle and toes by means of the strain gauge technique has been assessed in 20 patients with peripheral arterial disease. S.D difp between first and second determinations in double measurements lies between 4 and 6 mm Hg. The variation in gradient arm-leg was a little higher (S.D.difp about 7 mm Hg). In spite of very accurate procedure, day-to-day variation was between 7 and 10 mm Hg according to both distal pressures and arm-leg gradients. No difference in reproducibility was demonstrated, when patients with very low distal pressures and patients with moderately reduced pressures were compared. During measurements on a tilt table in several positions, it was demonstrated in 5 patients with severe peripheral arterial disease that the measured systolic toe blood pressures in the different positions deviated only a few mm Hg from the expected blood pressures, calculated from the changes in hydrostatic levels of arm and toe, and the change in systolic arm blood pressure. In conclusion it can be stated, that the reproducibility of strain gauge measurements at ankle and toe is fairly good both in patients with severe arterial disease and in patients with moderately reduced digital blood pressure. Expressed in mm Hg, the upper variation between double measurements on two different days is about 20 mm Hg, irrespective of the height of the digital blood pressure. During measurement on a tilt table extremely good correlation was demonstrated between the expected and the measured systolic blood pressures, with a tendency of the measured blood pressures to be a few mm higher than the expected pressures.