Hemofiltration in Acute Liver Failure: Substition with Electrolyte Solution Versus Normal Animal Ultrafiltrate

Current knowledge of the pathogenesis of hepatic coma suggests that putative toxins such as ammonia, mercaptans, and aromatic amino acids play a major role, while the contribution of deficient liver-dependent factors is as yet unsettled. To determine the role of deficient factors, functionally anhepatic pigs undergoing hemofiltration with reinfusion of a standard electrolyse solution were compared with another group of animals treated with hemofiltration with reinfusion of ultrafiltrate obtained from normal pigs. A third control group underwent a sham hemofiltration procedure. Hemofiltration was started 18 h after functional hepatectomy and continued for 4 h twice daily until death or for 60 h. The mean duration of survival after functional hepatectomy was 47 h for standard hemofiltration, 35 h for hemofiltration with normal animal fluid reinfusion, and 33 h for controls. Clearances of putative toxins were identical (∼ 80 ml/min) in both hemofiltration procedures, resulting in equal reductions in blood tyrosine concentrations in comparison to controls. During standard hemofiltration, levels of blood ammonia fell significantly lower than in controls; reinfusion of the ammonia precursor urea apparently prevented such a fall in blood ammonia concentrations in hemofiltation with normal animal fluid reinfusion.