Comparison of two different parameters for elimination of TNF a from circulating blood by continuous hemofbltration during endotoxemia

Introduction: There is a controversy on whether continuous hemofiltration (CHF) can eliminate tumor necrosis factor-α(TNFα) from plasma. The aim of this study was to evaluate removal efficiency of CHF using two different parameters. Methods: Thirteen pigs received intravenous E-coli endotoxin (10 μg/kg/hr), CHF and lactated Ringer's resuscitation in a common regimen for 24 hours. CHF was started 30 minutes after initiation of endotoxin and continued until the end of the experiment (filter sieving property < 21,000 Daltons, circuit flow 100 ml/min, filtration rate 1,000 ml/hr, equivalent lactated Ringer's solution replaced). Samples from prefilter, postfilter and filtrate were obtained periodically (0, 1, 2, 4, 7, 12, 24 hrs) and TNFαwas analyzed by ELISA. At every time point, sieving coefficient (SC) and removal coefficient (RC) were calculated by the following formula. SC = 100 × Cfil/Cpre, RC = 100 × Cpost/Cpre, (Cpre, Cpost, Cfil; concentrations of prefilter plasma, postfilter plasma, and filtrates) Results: Six of 13 animals died before termination of study. Data obtained from those animals were included in the analysis. Both axes of the figure were scaled in logarithmic order. There was a strong negative correlation between Cpre and SC (logSC = -.952 logCpre + .749, r²= .966, p<.001), whereas no significant correlation was found between Cpre and RC. Conclusions: TNFαcan be filtered at a fixed rate by CHF. However, this amount of removal did not affect RC. This discrepancy between SC and RC may contribute to the disparate results in hemofiltration studies reported by different authors.