Objective: To test whether hemofiltration using a hemofilter with large pores (super high flux hemofiltration) achieves effective cytokine removal.
Design: : Ex vivo study.
Setting: Laboratory of an intensive care unit in a tertiary hospital.
Patients and participants: Five healthy volunteers.
Interventions: Blood was spiked with 1 mg of endotoxin and then circulated through a closed hemofiltration circuit with a large pore polyamide super high flux hemofilter (nominal cut-off point: 100 kDa). Hemofiltration was conducted at 1 l/h or 6 l/h of ultrafiltrate flow. Samples were taken from the arterial, venous and ultrafiltration sampling ports.
Measurements and results: Sieving coefficients (SC) above 0.6 were achieved for interleukin (IL)-1beta, IL-6 and IL-10 and SCs above 0.3 were achieved for IL-8 and TNF-alpha at 1 l/h. SCs of all cytokines (except IL-1) were reduced when the ultrafiltration rate was increased from 1 l/h to 6 l/h ( p<0.01), but cytokine clearances still increased ( p<0.01). The highest SC for albumin was 0.1 at 1 l/h and fell to 0.01 at 6 l/h. No adsorption of cytokines and albumin was observed.
Conclusion: High volume ultrafiltration using a super high flux filter achieved cytokine clearances comparable to, or greater than, those currently achieved for urea during standard continuous renal replacement therapy.