Safe use of segmental liver grafts from donors after cardiac death (DCD) in children with acute liver failure

Use of DCD organs: Expanding the donor pool to increase pediatric transplantation

The number of children being listed for transplant continues to be greater than the number of available organs. In fact, over the past decade, rates of liver and kidney transplants in pediatric transplantation are essentially unchanged (Am J Transplant. 2020;20:193 and Am J Transplant. 2020;20:20). The use of DCD donors offers a potential solution to organ scarcity; however, the use of DCD organs in pediatric transplantation remains a rare event. Pediatric transplants done using carefully chosen DCD donor organs have shown to have outcomes similar to those seen with the use of donation after brain death (DBD) donors. Herein, we review the literature to examine the utilization of DCD livers and kidneys, outcomes of these allografts, and assess if DCD organs are a viable method to increase organ availability in pediatric transplantation.

Long-term outcomes of pediatric liver transplantation using organ donation after circulatory death: Comparison between full and reduced grafts

BACKGROUND

The shortage of donors' livers for pediatric recipients inspired the search for alternatives including donation after cardiac death (DCD).

METHODS

Retrospective review of pediatric liver transplant (PLT) using DCD grafts. Patients were divided into either FLG or RLG recipients. Pre-transplant recipient parameters, donor parameters, operative parameters, post-transplant recipient parameters, and outcomes were compared.

RESULTS

Overall, 14 PLTs from DCD donors between 2005 and 2018 were identified; 9 FLG and 5 RLG. All donors were Maastricht category III. Cold ischemia time was significantly longer in RLG (8.2 h vs. 6.2 h; p = .038). Recipients of FLG were significantly older (180 months vs. 7 months; p = .012) and waited significantly longer (168 days vs. 22 days; p = .012). Recipients of RLG tended to be sicker in the immediate pre-transplant period and this was reflected by the need for respiratory or renal support. There was no significant difference between groups regarding long-term complications. Three patients in each group survived more than 5 year post-transplant. One child was re-transplanted in the RLG due to portal vein thrombosis but failed to survive after re-transplant. One child from FLG also died from a non-graft-related cause.

CONCLUSIONS

Selected DCD grafts are an untapped source to widen the donor pool, especially for sick recipients. In absence of agreed criteria, graft and recipient selection for DCD grafts should be undertaken with caution.

Donation after Circulatory Death Liver Transplantation in Paediatric Recipients

Waiting list mortality together, with limited availability of organs, are one of the major challenges in liver transplantation (LT). Especially in the paediatric population, another limiting factor is the scarcity of transplantable liver grafts due to additional concerns regarding graft size matching. In adults, donation after circulatory death (DCD) liver grafts have been used to expand the donor pool with satisfactory results. Although several studies suggest that DCD livers could also be used in paediatric recipients with good outcomes, their utilisation in children is still limited to a small number of reports. Novel organ perfusion strategies could be used to improve organ quality and help to increase the number of DCD grafts utilised for children. With the current manuscript, we present the available literature of LT using DCD grafts in paediatric recipients, discussing current challenges with the use of these livers in children and how machine perfusion technologies could be of impact in the future.

Should We Be Utilizing More Liver Grafts From Pediatric Donation After Circulatory Death Donors? A National Analysis of the SRTR from 2002 to 2017

BACKGROUND

Rates of withdrawal of life-sustaining treatment are higher among critically ill pediatric patients compared to adults. Therefore, livers from pediatric donation after circulatory death (pDCD) could improve graft organ shortage and waiting time for listed patients. As knowledge on the utilization of pDCD is limited, this study used US national registry data (2002-2017) to estimate the prognostic impact of pDCD in both adult and pediatric liver transplant (LT).

METHODS

In adult LT, the short-term (1-year) and long-term (overall) graft survival (GS) between pDCD and adult donation after circulatory death (aDCD) grafts was compared. In pediatric LT, the short- and long-term prognostic outcomes of pDCD were compared with other type of grafts (brain dead, split, and living donor).

RESULTS

Of 80 843 LTs in the study, 8967 (11.1%) were from pediatric donors. Among these, only 443 were pDCD, which were utilized mainly in adult recipients (91.9%). In adult recipients, short- and long-term GS did not differ significantly between pDCD and aDCD grafts (hazard ratio = 0.82 in short term and 0.73 in long term, both P > 0.05, respectively). Even "very young" (≤12 y) pDCD grafts had similar GS to aDCD grafts, although the rate of graft loss from vascular complications was higher in the former (14.0% versus 3.6%, P < 0.01). In pediatric recipients, pDCD grafts showed similar GS with other graft types whereas waiting time for DCD livers was significantly shorter (36.5 d versus 53.0 d, P < 0.01).

CONCLUSIONS

Given the comparable survival seen to aDCDs, this data show that there is still much scope to improve the utilization of pDCD liver grafts.

The Human Immune Response to Cadaveric and Living Donor Liver Allografts

The liver is an important contributor to the human immune system and it plays a pivotal role in the creation of both immunoreactive and tolerogenic conditions. Liver transplantation provides the best chance of survival for both children and adults with liver failure or cancer. With current demand exceeding the number of transplantable livers from donors following brain death, improved knowledge, technical advances and the desire to prevent avoidable deaths has led to the transplantation of organs from living, ABO incompatible (ABOi), cardiac death donors and machine based organ preservation with acceptable results. The liver graft is the most well-tolerated, from an immunological perspective, of all solid organ transplants. Evidence suggests successful cessation of immunosuppression is possible in ~20–40% of liver transplant recipients without immune mediated graft injury, a state known as “operational tolerance.” An immunosuppression free future following liver transplantation is an ambitious but perhaps not unachievable goal. The initial immune response following transplantation is a sterile inflammatory process mediated by the innate system and the mechanisms relate to the preservation-reperfusion process. The severity of this injury is influenced by graft factors and can have significant consequences. There are minimal experimental studies that delineate the differences in the adaptive immune response to the various forms of liver allograft. Apart from ABOi transplants, antibody mediated hyperacute rejection is rare following liver transplant. T-cell mediated rejection is common following liver transplantation and its incidence does not differ between living or deceased donor grafts. Transplantation in the first year of life results in a higher rate of operational tolerance, possibly due to a bias toward Th2 cytokines (IL4, IL10) during this period. This review further describes the current understanding of the immunological response toward liver allografts and highlight the areas of this topic yet to be fully understood.

Donation after circulatory death liver transplantation: What are the limits for an acceptable DCD graft?

The utilization of donation after circulatory death (DCD) livers has been growing over the last decade. In large-volume centers, survival outcomes have improved and are comparable to outcomes with brain death donor (DBD) liver transplantation (LT). The relatively concentrated success with DCD LT demonstrated by high-volume transplant centers has rekindled international enthusiasm. The combination of increasing expertise in DCD LT and ongoing shortage in transplantable organs has promoted expansion of the DCD donor pool with regards to donor age, body mass index and donor warm ischemia time. In this review, we focused on the practice patterns in DCD liver graft utilization in the last decade, along with the possibilities for further expansion of DCD liver graft utilization and new technologies, such as machine perfusion.

Donation after Circulatory Death in Paediatric Liver Transplantation: Current Status and Future Perspectives in the Machine Perfusion Era

Efforts have been made by the transplant community to expand the deceased donor pool in paediatric liver transplantation (LT). The growing experience on donation after circulatory death (DCD) for adult LT has encouraged its use also in children, albeit in selective cases, opening new perspectives for paediatric patients. Even though there has recently been a slight increase in the number of DCD livers transplanted in children, with satisfactory graft and patient outcomes, the use of DCD grafts in paediatric recipients is still controversial due to morbid outcomes associated with DCD grafts. In this context, recent advances in the optimization of donor support by extracorporeal membrane oxygenation and in the graft preservation by liver machine perfusion could find application in order to expand the donor pool in paediatric LT. In the present study we review the current literature on DCD liver grafts transplanted in children and on the use of extracorporeal donor support and liver perfusion machines in paediatrics, with the aim of defining the current status and future perspectives of paediatric LT.

Long-term results after transplantation of pediatric liver grafts from donation after circulatory death donors

Background

Liver grafts from donation after circulatory death (DCD) donors are increasingly accepted as an extension of the organ pool for transplantation. There is little data on the outcome of liver transplantation with DCD grafts from a pediatric donor. The objective of this study was to assess the outcome of liver transplantation with pediatric DCD grafts and to compare this with the outcome after transplantation of livers from pediatric donation after brain death (DBD) donors.

Method

All transplantations performed with a liver from a pediatric donor (≤16 years) in the Netherlands between 2002 and 2015 were included. Patient survival, graft survival, and complication rates were compared between DCD and DBD liver transplantation.

Results

In total, 74 liver transplantations with pediatric grafts were performed; twenty (27%) DCD and 54 (73%) DBD. The median donor warm ischemia time (DWIT) was 24 min (range 15–43 min). Patient survival rate at 10 years was 78% for recipients of DCD grafts and 89% for DBD grafts (p = 0.32). Graft survival rate at 10 years was 65% in recipients of DCD versus 76% in DBD grafts (p = 0.20). If donor livers in this study would have been rejected for transplantation when the DWIT ≥30 min (n = 4), the 10-year graft survival rate would have been 81% after DCD transplantation. The rate of non-anastomotic biliary strictures was 5% in DCD and 4% in DBD grafts (p = 1.00). Other complication rates were also similar between both groups.

Conclusions

Transplantation of livers from pediatric DCD donors results in good long-term outcome especially when the DWIT is kept ≤30 min. Patient and graft survival rates are not significantly different between recipients of a pediatric DCD or DBD liver. Moreover, the incidence of non-anastomotic biliary strictures after transplantation of pediatric DCD livers is remarkably low.

Pediatric Donation After Circulatory Determination of Death: A Scoping Review

OBJECTIVE

Although pediatric donation after circulatory determination of death is increasing in frequency, there are no national or international donation after circulatory determination of death guidelines specific to pediatrics. This scoping review was performed to map the pediatric donation after circulatory determination of death literature, identify pediatric donation after circulatory determination of death knowledge gaps, and inform the development of national or regional pediatric donation after circulatory determination of death guidelines.

DATA SOURCES

Terms related to pediatric donation after circulatory determination of death were searched in Embase and MEDLINE, as well as the non-MEDLINE sources in PubMed from 1980 to May 2014.

STUDY SELECTION

Seven thousand five hundred ninety-seven references were discovered and 85 retained for analysis. All references addressing pediatric donation after circulatory determination of death were considered. Exclusion criteria were articles that did not address pediatric patients, animal or laboratory studies, surgical techniques, and local pediatric donation after circulatory determination of death protocols. Narrative reviews and opinion articles were the most frequently discovered reference (25/85) and the few discovered studies were observational or qualitative and almost exclusively retrospective.

DATA EXTRACTION

Retained references were divided into themes and analyzed using qualitative methodology.

DATA SYNTHESIS

The main discovered themes were 1) studies estimating the number of potential pediatric donation after circulatory determination of death donors and their impact on donation; 2) ethical issues in pediatric donation after circulatory determination of death; 3) physiology of the dying process after withdrawal of life-sustaining therapy; 4) cardiac pediatric donation after circulatory determination of death; and 5) neonatal pediatric donation after circulatory determination of death. Donor estimates suggest that pediatric donation after circulatory determination of death will remain an event less common than brain death, albeit with the potential to substantially expand the existing organ donation pool. Limited data suggest outcomes comparable with organs donated after neurologic determination of death. Although there is continued debate around ethical aspects of pediatric donation after circulatory determination of death, all pediatric donation after circulatory determination of death publications from professional societies contend that pediatric donation after circulatory determination of death can be practiced ethically.

CONCLUSIONS

This review provides a comprehensive overview of the published literature related to pediatric donation after circulatory determination of death. In addition to informing the development of pediatric-specific guidelines, this review serves to highlight several important knowledge gaps in this topic.

The bile duct in donation after cardiac death donor liver transplant

PURPOSE OF REVIEW

This review considers the biliary complications associated with liver transplantation using donation after cardiac death (DCD) donor grafts.

RECENT FINDINGS

The increasing use of DCD liver grafts with their increased incidence of biliary complications is discussed. The ethics of this greater use is briefly analysed. Recent animal and human study evidence to support the peribiliary vascular plexus' role in ischaemic cholangiopathy is reviewed. Recent advances in in-vivo and ex-vivo perfusion are explored. In particular, the latest theories regarding perfusion's peribiliary plexus preserving effects and the mechanism by which biliary regeneration may be promoted as a consequence are discussed.

SUMMARY

This article explores the need for DCD liver graft use and the associated biliary complications. The current theories regarding the cause of DCD biliary complications are reviewed, as are the current strategies to reduce them.

Segmental ABO-incompatible liver graft from a donor after cardiac death in neonatal acute liver failure

Segmental liver grafts from DCD in pediatric LT have been safely used even in acute liver failure situations. Furthermore, despite the risk of antibody-mediated acute rejection, some studies have also demonstrated the safety of ABO incompatible LT in infants. The use of such grafts can be beneficial by reducing the time on the transplant waiting list but they are more susceptible to initial dysfunction and there is a lack of enthusiasm to consider their use especially for an emergency LT as a life-saving procedure. In this short article, we describe the use and successful outcome in a neonate with fulminant acute liver failure secondary to neonatal hemochromatosis who received an ABO-incompatible reduced-size DCD graft.

Current status and recent advances of liver transplantation from donation after cardiac death

The last decade saw increased organ donation activity from donors after cardiac death (DCD). This contributed to a significant proportion of transplant activity. Despite certain drawbacks, liver transplantation from DCD donors continues to supplement the donor pool on the backdrop of a severe organ shortage. Understanding the pathophysiology has provided the basis for modulation of DCD organs that has been proven to be effective outside liver transplantation but remains experimental in liver transplantation models. Research continues on how best to further increase the utility of DCD grafts. Most of the work has been carried out exploring the use of organ preservation using machine assisted perfusion. Both ex-situ and in-situ organ perfusion systems are tested in the liver transplantation setting with promising results. Additional techniques involved pharmacological manipulation of the donor, graft and the recipient. Ethical barriers and end-of-life care pathways are obstacles to widespread clinical application of some of the recent advances to practice. It is likely that some of the DCD offers are in fact probably “prematurely” offered without ideal donor management or even prior to brain death being established. The absolute benefits of DCD exist only if this form of donation supplements the existing deceased donor pool; hence, it is worthwhile revisiting organ donation process enabling us to identify counter remedial measures.

Use of a liver from donor after cardiac death: is it appropriate for the sick or the stable?

PURPOSE OF REVIEW

Liver transplantation following donation after cardiac death (DCD) continues to be a subject for heated debate. Opinion is divided in the literature as to who benefits the most from receiving a liver from a DCD donor. This review will focus on some important questions regarding the outcome of transplantation and the selection and matching of donor and recipient.

RECENT FINDINGS

Liver transplantation with an organ from a donor after cardiac death is becoming an accepted way to treat patients on the waiting list with end-stage liver disease. However, there are still some major issues to address such as ischemic-type biliary lesions, retransplantation rates, criteria for donor and patient selection and whether conversion of donation after brain death to DCD exists. Accepting a DCD liver has the potential for reduced recipient quality of life after transplant. Death on the waiting list must be balanced against the inherent risks of a DCD liver.

SUMMARY

Success of liver transplantation is mostly measured as graft and patient survival. DCD liver transplantation is a potential tool to decrease mortality on the waiting list. Careful selection and matching of donor organ and recipient can lead to good outcomes. However, ischemic-type biliary lesions after DCD liver transplantation remain an important obstacle to overcome and have a serious impact on quality of life after transplantation.

Liver transplantation in children using non-heart-beating donors (NHBD)

Selected livers from controlled NHBD are accepted for OLT in adults. Recent evidence has shown good medium-term outcome. The purpose of this study was to report our experience of pediatric OLT with whole and partial grafts from NHBD, analyzing complications and outcome. Retrospective review of all the recipients who underwent primary OLT between December 2005 and December 2008, using livers from NHBD. Four children (one male child) mean age was 9.5 yr (0.2-17), mean weight was 26 kg (range 2.6-48), underwent OLT using NHBD. Mean donor age was 14.2 yr, and mean WIT (systolic BP<50 mmHg to cold perfusion) 12.2 min (range 10-15). Two children received reduced grafts and two full grafts. Mean cold ischemia time was 7.18 h (range 6-8). Liver function tests one wk and nine months post-OLT confirmed a good graft function. One child was treated for two episodes of acute rejection. Post-transplant complications included two cases of mild ischemic cholangiopathy treated conservatively. Graft and patient survival was 100% with a mean follow-up of 19 months (range 8.1-43.4). Short- to medium-term follow-up suggests that liver grafts from young NHBD with short warm and cold ischemia times can be safely utilized in pediatric transplantation.

Liver transplantation from donation after cardiac death donors: initial Belgian experience 2003-2007

The Belgian experience with donation after cardiac death (DCD) liver transplantation (LT) was retrospectively reviewed, particularly evaluating patient and graft survivals, and biliary complications. From 2003 to 2007, 58 DCD-LT were performed in Belgium. Mean procurement total warm ischemia time was 25 +/- 2 min (mean +/- SEM). Mean cold ischemia time was 451 +/- 18 min. Mean follow-up was 23 +/- 2.2 months. Post-transplant peak aspartate aminotransminases was 2241 +/- 338 UI/l. Patient survivals at 1 month, 1 and 3 years, were 91.3%, 83.3% and 66.9% respectively. Graft survivals at 1 month, 1 and 3 years, were 84.4%, 72.4% and 48.8% respectively. Two patients (3.4%) developed primary nonfunction. Regarding the biliary complications, seven grafts (12%) were lost because of intrahepatic cholangiopathy, and 12 other patients (20.6%) developed bile duct stenoses requiring endoscopic and/or surgical management. The rate of symptomatic ischemic biliary lesions for grafts surviving more than 3 months was 38% (19/50). Although DCD organ donors may be a source of viable liver grafts, results were inferior to those obtained with donation after brain death LT in this series. Prognostic criteria have to be developed to improve results of DCD-LT.