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

Abstract

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. Prospective, randomized study with age-matched controls. Biomedical research facility. Fourteen 4 to 8-wk-old, weaned Poland-China swine, weighing 5 to 10 kg. 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. 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 100-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. 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 filter 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.