PERIOPERATIVE CARE OF THE LIVER-TRANSPLANT PATIENT .2.

Because of the shortage of donor organs, it will remain uncommon to simultaneously transplant more than one organ into an individual recipient. Patients with primary hyperoxaluria and oxalosis may be referred for combined renal and hepatic transplantation. A small number of patients may benefit from combined heart and liver transplantation. There have been occasional reports of multiple organ transplantation in both adults and children. The liver has been transplanted as part of a visceral organ cluster, but the indications for these procedures are not well established (1). Organ procurement is critical to the growth of successful liver transplantation. Although there has only been a modest increase in the actual number of donors in the United States since 1986, up to 8957 patients annually (excluding alcoholics) may potentially benefit from OLT (256). It has been estimated that organs are harvested from only 15%-20% of the 15,000-20,000 potentially eligible cadaveric donors available each year (257). A truly systematic effort to establish routine inquiry about organ donation while patients are still alive and competent must be attempted (258). A more radical 'presumed consent' has been proposed by some authors, suggesting that organs from cadavers could be harvested without explicit consent, unless the potential donor expressed an objection before death or the donor's family objected at the time of death (257). Expanding the potential donor pool to include more elderly patients, patients with poor gas exchange, minor abnormalities of liver function, or chronic systemic diseases (such as diabetes mellitus), or those requiring vasoactive drugs may increase the number of available organs (1). In situ cooling techniques are being developed for improved organ retrieval. Use of University of Wisconsin preservation solution has extended the safe period of cold storage to as long as 24 h and has helped to overcome many of the logistic constraints associated with the OLT procedure. With recent advances in hepatobiliary surgery, new transplantation techniques have been developed. Recipient hepatectomy with preservation of the inferior vena cava and subsequent anastomosis of the donor hepatic veins onto the intact vena cava using a Carrel patch may avoid many of the problems associated with the suprahepatic caval anastomosis. This caval preservation technique may obviate the need for venovenous bypass. The allograft may be reperfused once the portal and hepatic venous anastomoses are completed. Other new techniques include reduced-size liver transplantation and preparing two viable grafts from one donor organ for use in two different recipients, the so-called split liver transplantation (259). Auxiliary liver transplantation has bene advocated for patients presenting with certain forms of acute hepatic failure and has now been described as treatment for chronic liver disease (1). The donor liver or lobe is transplanted into the right paravertebral gutter, leaving the diseased recipient liver in situ. Portal venous inflow is critical for survival of the auxiliary graft and is provided from the recipient's portal or superior mesenteric vein. The auxiliary graft is arterialized from convenient adjacent arteries. This strategy may keep the patient alive and allow the native liver to recover. Transplant immunology is a rapidly growing subspeciality, and there is an active search for more specific and less toxic immunosuppressive agents. The macrolide compound FK- 506 is 100 times as potent as cyclosporine and has been used successfully to treat intractable acute and chronic rejection (260). Monoclonal antibodies directed against T-lymphocyte subsets (CD3 and CD4) and against interleukin- 2 receptors or surface adhesion molecules may offer more specific immunosuppressive effects on activated T-lymphocytes. Induction of immune tolerance to donor histocompatibility antigens has been demonstrated in animal experiments.