Pre-measurement rest time affects magnitude and reliability of toe pressure measurements

Abstract

Objectives. Toe pressures are used to evaluate lower extremity healing capacity and screen for peripheral arterial disease (PAD). Although toe pressures are commonly used clinically both as an independent measure and in the calculation of the toe–brachial index, the effect of pre-measurement rest duration on the magnitude and reliability of toe pressures is unknown. This study investigated the effect of pre-measurement rest duration on toe pressures. Methods. Seventy community-based participants meeting guidelines for PAD screening were recruited. Systolic toe pressures either at the left or right hallux were manually measured using photoplethysmography following 5, 10 and 15 min of rest in a supine horizontal position. Testing was repeated 7–10 days later. Results. A significant drop in toe pressure (3.86 mmHg) occurred between 5 and 10 min (p = 0.001). No significant change occurred between 10 and 15 min. Reliability after 5 min was excellent (intra-class correlation coefficient, ICC = 0.80, 95% CI 0.68–0.89), increasing slightly at 10 and 15 min (ICC = 0.86, 95% CI 0.77–0.92 and ICC = 0.82, 95% CI 0.69–0.89). Conclusions. Toe pressures stabilize after 10 min of rest in a supine horizontal position. Longer periods of pre-measurement rest did not improve reliability significantly.