Predictability of sonographically assessed immediate post-operative blood flow and vein diameter on primary radio-cephalic fistula short and long-term outcomes

Introduction
Vascular access guidelines recommend radio-cephalic (RC) as first line vascular accesses for hemodialysis patients. However RCAVFs tend to have poorer outcomes  due to lower arterial blood flow (BF) and outflow vein calibre (VC). We assessed the accuracy and influence of immediate post-operative BF and VC on predicting their short and longterm outcomes.

Methods
This was a prospective single-centred study of multi-ethnic Asian hemodialysis patients whose primary RC AVF were created between October 2013 and October 2014 under regional anesthesia. All AVFs were assessed sonographically immediately after surgery for brachial artery BF and VC. Receiver operating characteristic (ROC) curves were generated to determine the optimal BF and VC cut-off for AVF maturation. Maturation was based on the rule of 6s.. Kaplan–Meier analysis was used to evaluate the AVF primary and secondary patency based best BF and VC cut-offs. Cox regression analysis interrogated  AVF failure risk factors.

Results
57 primary RCAVFs created in 20 pre-dialysis and 37 catheter-dependent ESRD patients were followed up for a median 49 (IQR 17-55) months. The median age of the study population was 58 (IQR 17-75) years. Sonography-based non-assisted maturation at 6 weeks was 56%. ROC identified 410 mL/min and 42mm as the best cut-off for BF and VC respectively to most accurately predict 6-week maturation. The sensitivity, specificity, positive predictive value and negative predictive value were 75%, 61%, 44% and 86% for BF 410 mL/min and 69%, 61%, 41% and 83% for VC 42mm respectively. Survival analysis showed (table 1) that AVFs with VC>42 mm had significantly greater 6 months, 1-year, 2-year and 4-year primary and secondary patency rates. There was no significant difference in patency rates with BF>410 and <410mL/min.

Conclusion
Immediate sonographically determined BF >410mL/min and VC>42mm can predict RCAVF nonassisted maturation, but only VC can accurately predict longterm AVF survival.