Big improvements for the smallest recipients

Neonatal candidates with liver failure are a particular challenge for the transplant surgeon, with the most common indications for liver transplantation (LT) being fulminant hepatic failure and gestational alloimmune liver disease (neonatal hemochromatosis). Reflecting severe functional impairment, this cohort has higher Pediatric End-Stage Liver Disease (PELD) scores than other pediatric age groups and a higher wait-list mortality compared with older pediatric patients and adults. Because typical donors and partial grafts are frequently too large for these tiny recipients, the general “rule of thumb” to use grafts that will result in less than a 4% graft-to-recipient weight ratio limits the available pool of donor organs. An alternative to whole organ transplant is to use a graft from a living donor, a reduced-size deceased donor, or split-liver deceased donor transplant. However, to prevent using grafts that are considered “too big” for the recipient, further reductions of the left lateral section or use of a monosegment is often required. This increases the technical complexity of the operation and may not be an appropriate option at all centers. In this issue of Liver Transplantation, Kasahara et al. present a series of 12 liver transplant recipients transplanted in the first 3 months of life, 11 of whom had fulminant hepatic failure. All patients received living donor transplants, with 11 of the grafts being reduced left lateral segments and 1 being a monosegment 2 graft. Despite having higher preoperative PELD scores, the neonatal cohort had excellent outcomes, with a 90.9% patient and graft survival with a median follow-up of 45 months. Adverse outcomes included a death due to respiratory syncytial virus and a relatively higher rate of biliary complications in the neonatal cohort. For pediatric recipients, surgical reduction of donor livers has been a successful strategy for using organs with a substantial size mismatch to the recipient. In the neonatal patient where fulminant liver disease is prominent, the liver is often atrophic or collapsed so that it is relatively rare for the recipient to have substantially augmented their abdominal domain through the presence of ascites or an enlarged cirrhotic liver. This small abdominal size makes graft reduction or delayed closure more critical. A major technical point highlighted in the current report is reduction of liver thickness to fit into the anterior-posterior diameter of the abdomen. Because this space is relatively fixed in the upper abdomen by the rib cage, compression from a large graft between the ribs and spine can occur. This often results in graft ischemia and may impair hepatic venous outflow, leading to multiple complications. Although the use of delayed abdominal closure with goretex (as is done in our center) or Bogota bags can allow for more space anteriorly, it does not always allow for substantial opening of the ribs in narrow abdomens. Although some studies have demonstrated inadequate perfusion and relative ischemia in large grafts, this phenomenon seems to be quite transient. Thus, the main consideration appears to be avoiding compression of the graft after closure. This point is reinforced by the outcomes of the current report, where the authors were able to perform primary abdominal closure in all neonatal recipients of reduced-size grafts even though 4/12 patients still received grafts over 4% of body weight and would be considered large-for-size. One factor that likely contributed to the outstanding outcomes in this case series is that all transplants were performed using living donors. In the United States, where deceased donation rates exceed those in Japan, the surgical team must consider using relatively sizematched whole livers, technical variant deceased donor Abbreviations: LT, liver transplantation; PELD, Pediatric EndStage Liver Disease.