Effect of Hemodialysis with Medium Cut-Off versus High-Flux Membranes on Endothelial Function of Patients with Chronic Kidney Disease

Introduction: Endothelial dysfunction (ED) is considered a marker of vascular complications, especially in patients with end-stage kidney disease (ESKD). Inflammation and the uremic state contribute to ED in patients undergoing hemodialysis (HD). Recently, the medium cut-off (MCO) dialysis membrane has been proposed to efficiently remove inflammatory cytokines and large, middle-sized uremic toxins, with the potential effect to improve endothelial function. This study aimed to compare the effect of dialysis with MCO or high-flux membranes on the endothelial function of patients on chronic HD. Methods: A prospective, randomized, crossover study in which 32 patients with ESKD were dialyzed for 12 weeks with each membrane, including a 4-week washout period between treatments. Endothelial function was assessed by flow-mediated dilation (FMD) using brachial artery ultrasound at weeks 1, 12, 16, and 28. Results: The population consisted of 59% men, 52.7 +/- 13.4 years, 16% non-black, on HD for 8.8 (4.1-15.1) years, and 72% with arteriovenous fistula. Hypertension was the most common etiology of chronic kidney disease, and 34% of patients had previous cardiovascular disease. Patients were grouped, regardless of treatment sequence, into MCO or high-flux groups, since no carryover (p = 0.634) or sequence (p = 0.998) effects were observed in the FMD assessment. The ANOVA model with repeated measures showed no effects of treatment (p = 0.426), time (p = 0.972), or interaction (p = 0.413) in the comparison of FMD between the MCO and high-flux groups. Conclusion: Dialysis performed with MCO, or high-flux membranes, had no influence on endothelial function in patients undergoing HD. However, a trend towards increased FMD was observed with the use of the MCO membrane.