Cytokine removal with a large pore cellulose triacetate filter: An ex vivo study

Objective: To test the hypothesis that hemofiltration using a new large pore cellulose triacetate hemofilter can achieve effective ultrafiltration of cytokines. Design: Ex-vivo study. Setting: Laboratory of Intensive Care Unit in tertiary hospital. Subjects: Six healthy volunteers. Interventions: Blood from 6 volunteers was incubated for 4 hours with 1 mg of endotoxin and then circulated through a closed hemofiltration circuit with a large pore cellulose triacetate hemofilter (nominal cut-off point: 60 kilodaltons). Hemofiltration was conducted at 1 L/h or 6 L/h of ultrafiltrate (UF) flow at the start of extra-corporeal circulation, and after 2 and 4 hours. Samples were taken from the arterial, venous and UF sampling ports. Measurements and main Results: IL-1beta, IL-6, IL-8, IL-10, TNFalpha, and albumin were measured. Sieving coefficients (SC) above 0.6 were achieved for IL-1beta and IL-6 and SCs above 0.3 were achieved for IL-8 and TNF-alpha at 1 L/h. Sieving coefficients of all cytokines (except IL-10, p=0.22) were reduced when the ultrafiltration rate was increased from IL/h to 6 L/h (p<0.01), but the increase in ultrafiltration rate resulted in an overall increase in the clearance of all cytokines (p<0.001). The highest SC for albumin was 0.07 at 4 hours at 1 L/h, and fell to 0.01 at 6 L/h. The SCs for IL-8 fell at 4 hours (p<0.01), but the SCs for other cytokines did not change. No adsorption of cytokines and albumin was observed. Conclusion: High volume hemofiltration (HVHF) using a new large pore cellulose triacetate filter achieved cytokine clearances greater than those reported with currently available hemofilters.