Is cytokine removal by continuous hemofiltration feasible?

Patients who are critically ill with acute renal failure and sepsis have ex tremely high mortality rates. While it seems reasonable that eliminating th e inflammatory mediators (such as cytokines, chemokines, tumor necrosis fac tor-alpha, etc.) by continuous renal replacement therapy (CRRT) would be ef fective, studies show that only insubstantial numbers of these mediators ar e removed in comparison with endogenous clearance. Mass removal seems only to be effective when highly permeable membranes (sieving coefficient of app roximately 1.0) are used, there is a filtrate volume greater than 2 liters/ hour, and when the half-life of the substance to be eliminated is greater t han 60 minutes. Removal of cytokines by membrane adsorption is another poss ibility. However, because the membrane surfaces are saturated after a few h ours, frequent filter changes are necessary for them to generate effective adsorption of these mediators. Despite filter changes, only a brief and tra nsient drop in the TNF plasma level has been observed. Controlled clinical trials are needed to determine whether or not CRRT actually has a beneficia l effect on the systemic inflammatory response syndrome (SIRS).