Dialyzer characteristics are associated with differential effects on intradialytic microvascular tissue perfusion

During hemodialysis (HD), microvascular perfusion is often compromised. These repeated ischemic insults can cause irreversible tissue damage in a variety of crucial organs. The role of dialyzer characteristics and general biocompatibility in this process is unknown. Clinical studies suggest a better biocompatibility profile for newer mid-cut-off (MCO) dialyzers when compared to conventional high-flux polysulfone (PSF). This study compared the effects of HD using either high-flux PSF or MCO dialyzers on microvascular perfusion in an established preclinical rat model of HD.

HD using in-house manufactured mini-dialyzers was performed on 30 male Wistar Kyoto rats while simultaneously observing and quantifying microvascular perfusion in skeletal muscle using intravital microscopy.

HD using PSF dialyzers resulted in a significant reduction (25%) in microvascular perfusion, which was not found in HD using an MCO dialyzer. Blood pressure reduction was similar between the two groups, while the expected tachycardic response was better conserved in the MCO group. We found no difference in solute clearance or circulating electrolyte levels during the procedure. The mini-dialyzers effectively removed urea and creatinine, indicating the functionality of this experimental procedure. We observed increased plasma levels of C5b-9 following a PSF-HD, indicative of a higher bioactivation of the complement pathways.

The results in our study show that this small animal model allows to preclinically evaluate new membrane materials and dialyzer designs in vivo. Our results show that different dialyzer membranes have different effects on microvascular perfusion. Although our analysis suggests a potential role for complement activation, the mechanisms underlying these differences and their clinical significance require further study.