Comparison of Different Membranes for Continuous Renal Replacement Therapies: An In Vitro Study

Inflammatory mediators play a major role in the development and progression of acute kidney injury (AKI). Continuous renal replacement therapy (CRRT) removes these mediators from the blood using AN69-M, AN69-ST, and HF1400 filters to target low and middle-molecular weight molecules. We characterized the in vitro removal performance of each filter in a 72 hour simulated CRRT procedure. Urea clearance with AN69-M and AN69-ST remained stable (52.4 and 51.2 ml/minute, respectively) but decreased with HF1400 (47.0 ml/minute; p < 0.001). Vancomycin clearance remained stable for AN69 filters but decreased for HF1400. Interleukin (IL)-8 was removed primarily via adsorption with the AN69 filters (92.2 and 91.2 ml/minute for AN69-M and AN69-ST, respectively), but clearance was significantly lower with HF1400 (8.4 ml/minute). Tumor necrosis factor (TNF)-α clearance was higher with AN69-ST compared with AN69-M or HF1400 (10.3, 1.8, and 2.3 ml/minute, respectively). β 2 -microglobulin clearance was higher with both AN69-based filters. The hydrogel water repartition of AN69 filters was different, with a higher percentage of bound water in AN69-ST versus AN69-M (30.5% ± 0.2% and 19.3% ± 1.5%, respectively; p < 0.05). These results suggest that clearance profiles of CRRT filters differ according to their properties; further investigation is needed to translate this into clinical improvements.