Endothelial Function Assessment with Endo-PAT

Endo-PAT2000 was obtained from Itamar Medical Ltd, Israel. Endo-Pat was performed at baseline and at 24 hours following the clamp study. All tests were performed by the same operator, with the subject in the fasting state, and in a quiet and temperature-controlled room (23 °C) with the participant relaxed in a semi-recumbent position. Probes were placed on the index finger of each arm to measure peripheral arterial tone (PAT). PAT was recorded in both arms for the duration of the test. After 5 minutes of rest (baseline), the blood pressure cuff was inflated to 220–230 mmHg to stop the blood supply in the study arm for 5 minutes, and then deflated to release the blood supply for a further 5 minutes. A reactive hyperemic index (RHI) is a measure of the change in PAT in the study arm after occlusion compared to baseline, and adjusted for changes in the control arm. Bonetti et al.^{28 (link)} reported that a measurement of RHI lower than the cut-off value of 1.67 provides a sensitivity of 82% and a specificity of 77% in diagnosing coronary endothelial dysfunction. Endo-PAT reproducibility was within acceptable limits, ICC = 0.74, and coefficient of variation 12 ± 2.2%^{29 (link)}.