Dialysis Efficiency of AN69, a Semisynthetic Membrane Not Well Suited for Diffusion

AN69 membrane is not suited for diffusion, with an suggested limit at 25 mL/min dialysate flow rate. When prescribing continuous hemodialysis this threshold must be surpassed to achieve. We designed a study aimed to check if a higher dose of dialysis could be delivered efficiently with this membrane. Ten ICU patients under continuous hemodiafiltration with 1.4 m(2) AN69 membrane were included and once a day we set the monitor to exclusively 50 mL/min dialysate flow rate and 250 mL/min blood flow rate and after 15 minutes measured dialysate saturation for urea, creatinine, and β 2-microglobulin. We detected that urea saturation of dialysate was nearly complete (1.1 ± 0.09) for at least 40 hours, while creatinine saturation showed a large dispersion (0.86 ± 0.22) and did not detect any relation for these variables with time, blood flow, or anticoagulation regime. Saturation of β 2-microglobulin was low (0.34 ± 0.1) and decreased discretely with time (r (2) = 0.15, P < 0.05) and significantly with TMP increases (r (2) = 0.31, P < 0.01). In our experience AN69 membrane shows a better diffusive capability than previously acknowledged, covering efficiently the range of standard dosage for continuous therapies. Creatinine is not a good marker of the membrane diffusive capability.