Sara Rioja

BACKGROUND: Native arteriovenous fistula (AVF) is considered the gold standard of vascular access for hemodialysis due to its longer survival, fewer complications, lower mortality and costs. Patency is important for effective dialysis treatment and this remains a challenge in nephrology. There are no well-defined prognostic factors for early and long-term AVF survival. The aim of this study was to evaluate comorbidity, analytical and ultrasound (US) variables as prognostic factors for early failure and AVF patency. METHODS: A prospective single-center cohort study was conducted with 5 years of follow-up. Inclusion criteria were patients with new native AVF creation between January 2011 and December 2015 and known vascular access survival data at the end of follow-up. Comorbidity (blood pressure, severe arteriopathy, diabetes, Charlson Index), and laboratory data (hemoglobin, calcium, phosphorus, PTH, ferritin, C-reactive protein), as well as US preoperative mapping (morphology and hemodynamic), were collected. End-points were early failure and secondary patency by Kaplan-Meier. RESULTS: The study included 117 patients with native AVF. Median age was 69±18 years and mainly of male gender (N.=70, 59.8%). Hypertension, diabetes and severe vascular disease were present in 65 (86.7%), 38 (50.7%) and 31 (41.3%). In 55 patients (47.8%) the AVF was in a distal location. Early failure was 19.7% and secondary patency at 5 years was 66.7%. Elderly age (P=0.034) and vein diameter (P=0.041) had an impact on early AVF failure. Radial (P=0.006) and ulnar peak systolic velocity (PSV) (P=0.018) showed predictive value in native AVF secondary patency rate. CONCLUSIONS: Predictors of early and late events are slightly different. Elderly age and vein diameter had greater impact on early AVF failure. However, distal arterial hemodynamics showed prognostic value in native AVF secondary patency rate.

INTRODUCTION AND AIMS: After arteriovenous fistula formation, vascular flow increased by venous dilation and vascular remodeling. The patency of vascular access is mandatory for maintenance hemodialysis. Nephrologist have always tried to improve the vascular access by various method like physical exam, Doppler ultrasound and so on. We hope to share our experience of vascular flow monitoring with hemodilution method. METHODS: We collected patients' data which access flow was checked at least 6 times and more from Nov. 2014 to Dec. 2016. The data included fistula flow, fistula formation date, dialysis adequacy, sex, age and cause of dialysis. Fistula flow was measured by hemodilution method (Transonic HD03) during the dialysis session at every month. Kt/V was checked at every 3 month. Vascular intervention for maintaining flow was done by the result of HD03 (< 450 ml/min) or physical examination. RESULTS: The 118 patients were monitored and 38 patients got vascular intervention (1 thrombolysis, 1 re-creation and 36 balloon dilatation). The 18 patients needed intervention despite of adequate access flow and there were no difference with adequate flow group in terms of underlying disease (diabetes, p = 0.8), Kt/V (p = 0.7), and fistula category (native/graft; p = 0.2, upper/forearm; p = 0.5). The 9 patients could maintain vascular access without intervention despite of low flow and they all had native fistula at forearm. CONCLUSIONS: Vascular monitoring by hemodilution method is easy, convenient and helpful. However, we should keep in mind that good vascular flow with hemodilution method is not always guarantee the fistula patency. Stenotic vascular lesion could not be distinguished by access flow only. Comprehensive approach is needed for better survival of vascular access.