The effect of pretest rest time on automated measures of toe systolic blood pressure and the toe brachial index

Objectives Evaluation of peripheral blood supply is fundamental to risk categorization and subsequent ongoing monitoring of patients with lower extremity peripheral arterial disease. Toe systolic blood pressure (TSBP) and the toe brachial index (TBI) are both valid and reliable vascular screening techniques that are commonly used in clinical practice. However, the effect of pretest rest duration on the magnitude of these measurements is unclear. Methods Eighty individuals meeting current guidelines for lower extremity peripheral arterial disease screening volunteered to participate. The Systoe and MicroLife automated devices were used to measure toe and brachial systolic blood pressures, respectively, following 5, 10 and 15 min of rest in a horizontal supine position. A ratio of TSBP to brachial pressure was used to calculate the TBI and change in TBI at each time interval was investigated. Results A significant increase in TSBP [3.66 mmHg; 95% confidence interval (CI): 1.44.5.89; P.0.001] and the TBI (0.03; 95% CI: 0.01.0.05; P.0.001) occurred between 5 and 10 min. Between 10 and 15 min, there was a nonsignificant decrease in TSBP (.0.73 mmHg; 95% CI: .1.48 to 2.93; P=1.000) and the TBI (0.00; 95% CI: .0.02 to 0.02; P=1.000). Conclusion Ten minutes of pretest rest is recommended for measurement of TSBP and for both pressure measurements used in the calculation of a TBI to ensure that stable pressures are measured.