The effect of coupled haemofiltration and adsorption on inflammatory cytokines in an ex vivo model

Background. The objective of this study was to evaluate the ex vivo removal of cytokines with an extracorporeal circuit using coupled large-pore haemofiltration and sorbent adsorption. Methods. The setting for this study was a laboratory attached to the Intensive Care Unit of a tertiary hospital. Six healthy volunteers donated blood, which was incubated with endotoxin. Control blood was left at room temperature. Treatment blood was recirculated for 6 h through a closed circuit with a large-pore polysulfone haemofilter (average pore size 150 kDa) and an activated charcoal cartridge. Blood and ultrafiltrate were sampled hourly from three sites (prehaemofilter for the circulating concentration, at cartridge inlet and cartridge outlet) to measure the concentrations of interleukins (IL)-1beta, -6, -8 and -10, and tumour necrosis factor (TNF). Results. Control cytokine concentrations remained the same or increased slightly. Most of the preformed circuit cytokines were removed, with the exception of IL-10. The average sieving coefficients were 0.61 for IL-1beta, 1.34 for IL-6, 0.30 for IL-8, and 0.56 for TNF. Average single-pass clearances were 49, 107, 24 and 45 ml/min, respectively. The cartridge adsorbed 90% of IL-1beta, 72% of IL-6, 100% of IL-8, and 7% of TNF during each pass. Conclusion. The combination of a large-pore haemofilter and charcoal cartridge removed several cytokines efficiently under ex vivo conditions. This technique can now be tested for cytokine removal in vivo.