Outcomes of Haemodialysis Arteriovenous Fistula Creation and Factors That Affect the Maturation of the Created Arteriovenous Fistulae at Kenyatta National Hospital

Abstract

Background: The arteriovenous fistula is the preferred long-term vascular access for chronic haemodialysis, due to its prolonged primary patency rates, has the fewest interventions and is associated with decreased morbidity and mortality. Despite being the preferred choice of haemodialysis access, AVF still has a relatively high primary failure rate related to various factors. There has been no study done in our institution and in Kenya to determine the outcomes of AVF creation and the factors that affect the maturation of the created AVF. Objective: To determine the outcomes of AVF creation and the factors that affect the maturation of the created AVFs at KNH in patients with ESRD requiring chronic haemodialysis. Methodology: The study was a prospective cohort study of patients with ESRD who had an AVF created for haemodialysis at KNH from October 2020 to April 2021. Prior to creation of the AVF, the vein and artery diameters were determined using duplex ultrasonography. These patients were then reviewed at 8 and 12 weeks after creation of the AVF, to determine the diameter of the vein with duplex ultrasonography and also to determine whether they had successful dialysis using the created AVF. This study was conducted at KNH Thoracic and Cardiovascular Surgery unit. Data was entered and analysed by use of SPSS version 21. The percentage of people who had successful maturation of the created AVF was calculated as a proportion of those who had successful maturation of the created AVF over the total sample size and reported as a percentage. Patient demographics as well as other patient characteristics was analysed and presented as frequencies and proportions for categorical data, and as means or medians for continuous data. Results: During this time frame, 114 arteriovenous fistulas were created in 111 patients. Of the AVFs created, 56.1% (n=64) were brachiocephalic fistulas and 43.9% (n=50) were radiocephalic fistulas. The primary failure rate was 21.6% after excluding 3 patients who died during followup. Of the AVFs that failed, the radiocephalic fistulas were associated with a higher failure rate as compared with brachiocephalic fistulas, 62.5% (n=15) and 37.5% (n=9) respectively. The risk of primary failure was increased in patients with poor venous outflow and venous distensibility of < 50% as well as patients who had small diameter veins with a cut-off value of 2.25mm. Conclusion: Primary AVF failure, remains a major issue, since the arteriovenous fistula remains the preferred choice of haemodialysis access. This study has shown that the outcome of arteriovenous fistula creation in our institution is promising. Of note, is that a significant number of the AVFs created were radiocephalic fistulas. Vein internal diameter of greater than 2.25mm and good venous outflow and distensibility were noted to be important predictors of a successful outcome.