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 (pre-haemofilter 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.