An extracorporeal perfusion system to bridge pediatric liver transplant candidates

An extracorporeal liver perfusion system was designed to maintain cadaver livers in an oxygenated, normothermic state for bridging procedures for hepatic transplantation. Nonpulsatile high flow and pulsatile low flow blood are supplied to the portal venous (PV) and hepatic arterial (HA) circulations. Controlled low blood flow (5-10 cc/kg [patient]/min) is exchanged between the high flow extracorporeal perfusion circuit (1 cc/g [liver]/min) and the patient. The system was evaluated in perfusions of fresh, excised pig livers (n = 5). The average oxygen consumption was 9 ± 3 μl/g/min, and bile production averaged 4.7 μl/g/hr. Perfusion pressures and flows were normal in both the HA and PV circulations for about 4 hr. Pressures then gradually rose, especially in the HA circulation, causing flow to decrease, with subsequent mottling and discoloration of the liver. Red blood cell, platelet, and white blood cell counts fell continuously. Maintenance of liver function was assessed by clearance of an 80 mg taurocholic acid challenge. An average of 56% of injected acid was cleared from the perfused livers (n = 5) in the first half hour, compared with 90% and 25% for the in situ (n = 3) and unperfused (n = 3) control livers, respectively. The system consistently maintained livers in a moderately well functioning state through the first 4 hr of perfusion. Adequate support of animals with induced hepatic failure must now be demonstrated.