【Abstract】Objective To evaluate digital blood pressure for the diagnosis of hemodialysis access induced distal ischemia (HAIDI) by using photoplethysmography before and after arteriovenous fistula operation. Methods Sixty-two end stage renal disease patients were enrolled in this study, and 55 of them completed the flow-up investigation. Smoking habit, diabetes history and artery calcification evaluated by X-ray on forearm were collected. Before fistula operation, arterial blood pressure of brachial arteries was measured, and the systolic blood pressure at thumb, index and middle fingers of both hands were measured by photoplethysmography. After fistula operation for one day, one month and 3 months, ischemia in distal areas was evaluated by questionnaire, and arterial pressure in fingers and brachial arteries were retested. After the operation for one month and 3 months, digital blood pressure in fingers was measured under the condition that fistula blood flow was temporarily blocked by compression. The patients were then divided in to HAIDI group and non- HAIDI group. Results The prevalence of HAIDI was 16.1%, and the ischemia degree was around HAIDI1 and HAIDI2a. In 8 patients with HAIDI, the ischemia scores after the operation for one month and for 3 months were similar (Z=-0.368, P=0.713). After the operation for 3 months, the digital brachial index (DBI) of thumb, index and middle fingers in the fistula side were significantly lower in HAIDI group than in non- HAIDI group (t=- 4.915, - 4.448 and - 3.681 respectively; P＜0.001, 0.001 and P=0.001 respectively); Change in digital pressure (CDP) was significantly greater in HAIDI group than in non- HAIDI group (t=2.522, 3.316 and 2.187 respectively; P=0.015, 0.002 and P=0.033 respectively). At the operation day, and after the operation for one month and 3 months, DBI of the thumb, index and middle finger were significantly lower in the operation side than in the opposite side (t=-11.057, -10.374 and -8.117 respectively, P＜0.001, 0.001 and 0.001 respectively at the operation day; t=- 10.803, - 11.767 and - 9.526 respectively, P＜0.001, 0.001 and 0.001 respectively after the operation for one month; t=-10.684, -9.952 and -8.080 respectively, P＜0.001, 0.001 and ＜0.001 respectively after the operation for 3 months). Analysis of variance showed significant differences in DBI among thumb, index and middle fingers (F=11.261, 6.342 and 6.697 respectively, P＜
0.05, P=0.002 and 0.002 respectively). After the operation for one month and 3 months, blood pressure in thumb, index and middle fingers increased significantly when fistula blood flow was temporarily blocked by compression (t=-14.457, -15.679 and -15.087 respectively, P＜0.001, 0.001 and 0.001 respectively after the operation for one month; t=-12.671, -14.087 and -14.854 respectively, P＜0.001, 0.001 and 0.001 respectively after the operation for 3 months). Using thumb DBI for the diagnosis of HAIDI, the area under the receiver operating characteristic (ROC) curve was the biggest. When the value of the thumb DBI was set at 0.595, the sensitivity for the diagnosis of HAIDI was 0.900 and specificity was 0.822. Conclusion The finger pressure and DBI in fistula limb were significantly decreased after arteriovenous fistula operation. The thumb DBI can be used for the diagnosis of HAIDI, and CDP is an early warning for HAIDI.
