Impact of Arteriovenous Fistula Flow Dynamics on Haemodialysis Adequacy: A Practical Approach in Resource-Limited Settings

Background Chronic kidney disease represents a significant public health burden in Sri Lanka, where the majority of patients with end-stage renal disease rely on haemodialysis as their primary renal replacement therapy. Most patients receive haemodialysis through arteriovenous fistulas (AVFs), which constitute the preferred vascular access modality. This study investigates the associations between flow dynamics and morphometric parameters of arteriovenous fistulas with dialysis adequacy, as measured by Kt/V ratios. Methods We conducted an analytical cross-sectional study from December 2024 to June 2025, recruiting patients undergoing regular long-term haemodialysis via AVF at dialysis units in Colombo North Teaching Hospital, Ragama, and Divisional Hospital Kandana, Sri Lanka. Access dimensions and peak systolic velocity (PSV) were measured using duplex ultrasonography. Patient demographics and clinical data were collected through structured interviews and medical record review, while dialysis parameters were obtained directly from dialysis machine monitors. Results Seventy-seven patients were enrolled, with 62.3% (n = 48) being male and a mean age of 55.97 years (SD 10.47). The mean PSV was 59.48 cm/s (SD 24.11). Adequate dialysis (Kt/V ≥ 1.2) was achieved in 76.6% (n = 59) of patients, with a population mean Kt/V of 1.51 (SD 0.46). PSV was significantly higher in patients achieving adequate dialysis (p = 0.008). Both linear and logistic regression models demonstrated significant associations between PSV and dialysis adequacy (p = 0.022 and p = 0.038, respectively). Receiver operating characteristic (ROC) analysis identified a PSV threshold of 72.5 cm/s, demonstrating high specificity (94.4%) but limited sensitivity (41%). Conclusion Haemodialysis adequacy, as measured by Kt/V, demonstrates a strong association with peak systolic velocity, suggesting PSV's potential utility as a surrogate indicator for dialysis effectiveness. The optimal PSV threshold for predicting adequate dialysis is 72.5 cm/s.