[Experimental studies on extracorporeal liver perfusion.--Development and evaluation of an improved circuit (author's transl)].

Clinical application of the extracorporeal liver perfusion has been rather limited mainly because of cumbersome procedure, not infrequent circulatory insufficiency due to large priming volume, and bleeding tendency due to hepatic insufficiency itself and heparinization, which are inherent with most of the currently available systems. A circuit was developed which employs siliconized tubings to eliminate heparinization. The liver is gravity perfused added with arterial pressure by utilizing A-V type blood access, thus eliminating the blood pump and oxygenator. A heat exchanger is eliminated by placing the liver in a moist liver chamber kept at 30 degrees C. Feasibility of the circuit was confirmed by 5 in vivo runs with healthy mongrel dogs who tolerated the procedure well. This circuit was further evaluated in dogs with acute hepatic failure induced by portacaval anastomosis and subsequent ligation of the proper hepatic artery 48 hours later. They were connected to the circuit when convulsion developed. Along with clinical observation, biochemical analysis were performed for samples obtained at the inlet (In-blood) and the outlet (Out-blood) of the liver chamber. Oxygen consumption with carbon dioxide production by the liver was confirmed in previous control experiment. Although temporarily, all animals showed recovery from convulsion. Ammonia level was invariably lower in Out-blood than in In-blood by approximately 70 gamma/dl. Blood sugar level was always higher in Out-blood by 40-70 mg/dl than in In-blood. Other parameters such as bilirubin, total protein, GOT and GPT levels were not significantly different. Technical feasibility and acceptable performance of the system were established in this study and its clinical evaluation is warranted.