Large-pore hemodialytic procedures in pigs with ischemic hepatic necrosis; a randomized study

In order to define further the therapeutic role of hemodialytic procedures in acute hepatic failure, 20 pigs with ischemic hepatic necrosis underwent randomized hemodialysis against an electrolyte solution (n = 6), hemofiltration with re-infusion of an electrolyte solution (n = 5), control hemofiltration with re-infusion of autologous ultrafiltrate (n = 4) or no extracorporeal procedure at all (n = 5). Pigs on hemodialytic procedures survived significantly longer (51 +/- 11 hrs) than controls (36 +/- 8 hrs). There were no differences in the duration of survival between hemodialysis and hemofiltration, nor between controls undergoing and those not undergoing an extracorporeal procedure. Electroencephalograms showed more rapid (p less than 0.05) deterioration in control animals than in the treatment group. Putative toxins such as ammonia, glutamine, tyrosine, tryptophan, and methionine all decreased transiently in the treatment group; in the control group a continuous increase in the levels of the putative toxins was observed. Comparison of all pigs surviving 35 hrs or less (n = 6) and animals surviving more than 45 hrs (n = 7) showed that long-term survival was significantly associated with lower plasma ammonia and methionine concentrations and fewer abnormalities on the electroencephalogram 10 hrs after the start of extracorporeal procedures; moreover six of the 7 long-term survivors underwent hemodialysis or hemofiltration procedures. We conclude that hemodialytic procedures prolong survival in pigs with ischemic hepatic necrosis by slowing the development of encephalopathy; this effect of hemodialytic procedures may be mediated by the lowering of plasma ammonia and methionine levels.