Effects of filter pore size on efficacy of continuous arteriovenous hemofiltration therapy for Staphylococcus aureus-induced septicemia in immature swine

Objective: To evaluate the effect of hemofilter pore size on the efficacy of continuous arteriovenous hemofiltration (CAVH) in improving morbidity and mortality in an immature swine model of Staphylococcus aureus-induced septicemia. Design: Prospective, randomized study with age-matched controls. Setting: Biomedical research facility. Subjects: Fourteen 4 to 8-wk-old, weaned Poland-China swine, weighing 5 to 10 kg. Interventions: spontaneously breathing, ketamine-sedated swine (4 to 8 wks of age) were given an intravenous lethal dose of live S. aureus, Animals were then filtered with either a 50-kilodalton (kD) pore size filter (control) or a 100-kD pore size filter (experimental). No animals received antibiotics. Measurements and Main Results: Physiologic, biochemical, and hematologic parameters were measured in all animals every 1 to 3 hrs. Animals were monitored continuously and survival time (hr) was recorded (permanent survival = 168 hrs/7 days). Animals filtered with the 100-kD filter survived significantly longer than control animals (103 +/- 18 [SEM] vs. 56 +/- 9 hrs), The 10O kD-filtered group had one permanent survivor (168 hrs), Protein concentration of the ultrafiltrate obtained from the 100-kD-filtered animals was eight-fold higher than control ultrafiltrate. The protein removed did not contain a high percentage of albumin (as determined by autoanalyzer methods). No significant differences were seen in any of the other measured parameters. Conclusions: CAVH significantly improved survival in swine with S. aureus-induced sepsis. The superior performance of the 100-kD filter vs. the 50-kD filter suggests that higher molecular weight mediators that are not removed efficiently by the 50-kD tilter may be responsible for the morbidity and mortality seen in this model of sepsis, These mediators may be removed In greater proportion by our customized (100-kD pore size) filter.