Haemodialysis vascular access function in dialysis patients at the Kenyatta National Hospital

Abstract

Background The number of patients requiring renal replacement therapy (RRT) worldwide has been on the rise. Vascular access (VA) is the life-line for the majority of these patients when on haemodialysis (HD). VA related morbidity is a leading cause of hospitalization. Its function and patency is essential for efficient HD. There is a need to determine the VA performance to identify those that are dysfunctional since early intervention to improve blood flows would ensure longevity of use and preservation of future vascular access site options. Objective This study aims to evaluate the vascular access function in patients undergoing haemodialysis at the Kenyatta National Hospital (KNH). Methods This was a cross-sectional descriptive study. The participants were thirteen years and above, requiring RRT in the form of HD at the KNH renal unit, who gave written informed consent or assent. Consecutive sampling was employed to recruit 150 patients. A focused clinical examination was then undertaken to determine the type of VA. The peak and mean VA blood flow rate (BFR) were recorded during a single HD session. Pre and post dialysis blood samples were obtained for blood urea measurements used to determine the delivered dialysis dose. The mean VA BFRs for the session was then compared to the corresponding achieved dialysis dose. In addition, all patients with an arterio-venous fistula (AVF) fashioned had a Doppler Ultrasound evaluation of the vascular access. Results An analysis of the complete data of 150 patients was performed, the mean age of the study participants was 43 years. The cuffed tunnelled central venous catheter was the VA predominantly used by 46% of the study participants. The mean and peak blood flow was 311.5 mL/min and 368.3 mL/min respectively, non-cuffed non-tunnelled central venous catheter (CVC) performed poorly; only 47.5% achieved a mean blood flow rate above 300 mL/min as compared to AVF (87.5%) and cuffed tunnelled CVC (81.7%). The delivered mean Kt/V and urea reduction ratio (URR) were 1.5 and 69.8% respectively. Twenty-four percent of patients had a URR less than 65%. A higher mean blood flow rate was associated with a higher URR (p=0.004) and Kt/V (p=0.009). AVF stenosis was present in 12.5% and xiii thrombosis in 3% of patients. Aneurysms were the commonest complication in AVF at 46.9% but were not haemodynamically significant. Conclusion This study demonstrates that 74.7% of the vascular accesses in use for haemodialysis at the KNH renal unit delivered adequate blood flow rates. Cuffed tunnelled haemodialysis CVCs offered adequate blood flows and achieved good delivered dose of dialysis that were comparable to arterio-venous fistula. The non-cuffed non-tunnelled CVCs delivered poor blood flow rates and dialysis dose and were in use for longer than the recommended duration of two weeks. On the whole, arterio-venous fistula access had better blood flow rates and delivered dialysis dose, however there is need to have routine surveillance by measuring blood flow rates and delivered dialysis dose. Interventional procedures need also to be made affordable to prevent access loss.