Liver transplantation in the pig

Orthotopic porcine liver transplantation: operative technique

Considerable interest in experimental liver transplantation has been generated recently due to improvements in the results of clinical liver transplantation efforts. An operative technique for orthotopic porcine liver transplantation is presented which represents modifications of and improvements to previously published techniques. Salient features of the technique include (1) use of a diaphragmatic cuff for the suprahepatic inferior vena cava anastomosis, (2) use of a splenojugular shunt, (3) omission of caval shunts, and (4) use of isoflurane as the primary anesthetic agent. This operative technique has provided excellent survival rates in our transplanted animals.

Aspects of anaesthetic management of heterologous extracorporeal hepatic support in patients with acute liver failure

Some anaesthetic aspects of heterologous extracorporeal hepatic support for patients with acute liver failure have been investigated in animals and men. Two types of anaesthesia during hepatectomy in pigs were performed in 20 experiments divided into two groups. A convenient anaesthetic technique was found to be the combined use of neuroleptanalgesics, gamma-OH, small doses of thiopental sodium and nitrous oxide--oxygen mixture. The necessity for care in the procedure of temporary liver support for 'poor-risk' patients is outlined. A minimal use of drugs which are metabolized by the liver, and avoidance of potent analgesics, narcotics, hypotension and hypoxia are the main principles for safe extracorporeal hepatic assistance to critically ill patients.

Studies on the isolated perfused pig liver

Eighty perfusions of the isolated pig liver were performed using diluted pig blood. Although a high proportion of these perfusions were successful, there was sporadic filure of perfusion, usually manifested by rising hepatic arterial blood-pressure and decreasing total hepatic blood-flow.

The success rate of perfusion was improved by addition of low-molecular-weight dextran to the perfusate, the use of a less soluble siliconizing agent for the perfusion apparatus, and the use of new tubing for each perfusion. Preliminary flushing of the liver with Ringer-lactate reduced the success rate and, in unsuccessful perfusions, vaso-active drugs were ineffective in reducing raised vascular resistance.

Changes in the perfusate electrolyte, glucose, and enzyme patterns were sometimes observed but could not be related to perfusion success.

Perfused livers synthesized urea and bilirubin and incorporated 75Se-labelled methionine into protein. Perfused livers also conjugated bromsulphthalein (B.S.P.), but in unsuccessful perfusions the uptake of the dye from the perfusate was reduced and there was marked entry of conjugated B.S.P. into the perfusate.

Careful attention to the details of perfusate composition and perfusion conditions does increase the number of successful perfusions. Suggestions for further improvements are discussed.

The technical innovations suggested by these investigations are probably relevant to the preservation of the liver prior to clinical transplantation or to the preparation and perfusion of the porcine liver in the treatment of patients with acute liver failure.