Experimental Studies On Extracorporeal Xenohepatic Perfusion

Objective: To explore the anesthesia method and indexes changes of hemodynamics and blood gas on establishing acute liver failure model by total hepatic devascularization in canines , manage to alleviate the turbulence so that the animals survive the surgical trauma. On the other hand, to evaluate whether this model is a successful model of acute liver failure.Materials and Methods: Six canines were induced acute liver failure by portacaval shunt and total hepatic devascularization under inhalation anesthesia of Enflurane and N2O. Record parameters of hemodynamics, respiration and temperature continuously and parameters of blood gas at the time of base line, vessel clamping, loosening and closing abdomen. Record parameter changes of liver function every hour after operation, pathology of liver and brain specimens after death.Results: (1) The mean arterial pressure and respiratory tidal volume significantly decreased compared with base line before vessel clamping (p<0.05), while heart rate had no significant change (p>.05 ) .The temperature of canines decreased significantly compared with base line after anesthesia (p<0.05). (2) At the time ofvessel clamping, mean arterial pressure and central venous pressure significantly decreased, heart rate significantly increased compared with baseline (/7<0.01) . During the time of vessel clamping, HCOs" and pH significantly deceased (p, /K0.05) compared with base line. Instead ,the changes of K+ , Na+ , Cl" have no significant difference with base line (p>0.05) . (3) Blood ammonia, total bilirubin, and prothrombin time increased gradually, the levels of blood ammonia and total bilirubin showed significantly progressing elevation in accordance with time prolong (p<0.05). After 3h of surgical procedure, prothrombin time showed significantly progressing prolonging (p<0.05). (4) Mean survival time were 336.67?4.23 min respectively. All animals showed the sign of increased intracranial pressure, craniotomy after animal death found significant cerebral edema. HE stain of cerebral tissue found cerebral edema and necrosis of neuron. HE stain of liver showed completely necrosis after animal death.Conclusions: (1) Inhalation anesthesia of Enflurane and N2O proved to be a safe, effective and easy-controlling method on establishing acute liver failure model by total hepatic devascularization in canines. (2) Though alleviating the disturbance of hemodynamic, biochemical, blood gas indexes actively, canines can tolerate surgical trauma and develop to acute liver failure by portacaval shunt and total hepatic devascularization. (3) The model can reflect natural process of liver failure and provide an alternative model to test actual substitute effect and deficiency of extra liver assistant system.