Outcomes of Donation After Circulatory Death Liver Grafts From Donors 50 Years or Older: A Multicenter Analysis

Effect of frailty as measured by functional impairment on long-term outcomes in liver transplantation in the United States

BACKGROUND

In patients with chronic liver disease or hepatic dysfunction with sarcopenia, there is an increased risk of frailty as measured by functional impairment, making frailty a vital predictor of post-transplant mortality.

AIM

To investigate the effects of frailty on mortality after liver transplantation.

METHODS

A retrospective review of post-transplant outcomes in liver transplant recipients assessed frailty using Karnofsky Performance Score. Data from the Scientific Registry of Transplant Recipients database for 37427 liver transplant recipients was used.

RESULTS

Of 82.7% frail patients, 42.7% were severely frail and 40% were moderately frail (P < 0.001) at the time of transplantation. Compared with non-frail patients, post-transplant mortality in frail patients was significantly higher at 12 months [odds ratio (OR) = 1.94, P = 0.02)]. Secondary analysis of the data revealed that liver grafts from donation after circulatory death (DCD) were more likely to be associated with frail patients at transplant (OR = 1.86, P < 0.001). Furthermore, a donor history of hypertension was associated with a lower likelihood of frailty in the recipient at the time of transplant (OR = 0.65, P = 0.03).

CONCLUSION

Recipient frailty is associated with increased mortality at 12 months following liver transplantation, and liver transplants from donors with DCD are associated with increased frailty of the liver transplant recipient.

Current understanding on inferior quality of liver grafts by donation after circulatory death based on multi-omics data

Given the inevitable hypoxia and reperfusion injury that occur in organs donated after circulatory death (DCD), the quality and function of these organs are significantly compromised, greatly limiting their application in clinical organ transplantation. Recently, the advancement of functional omics technologies has enabled us to deeply analyze the mechanisms underlying DCD donor organ damage from multiple perspectives. This review systematically integrates the studies from transcriptomics, proteomics, and metabolomics to reveal the key biological mechanisms associated with the declines in DCD donor organ quality, including oxidative stress, inflammatory responses, cell death pathways, and metabolic disturbances. Additionally, we summarized emerging therapeutic strategies based on findings from omics perspectives, offering new possibilities to improve the quality of DCD organ for better transplant prognosis. Finally, we discussed the challenges in current research and future directions to provide scientific evidence for clinical practice and promote the application of DCD donors in organ transplantation.

Factors predicting lower hospital stay after liver transplantation using a comprehensive enhanced recovery after surgery (ERAS) protocol

INTRODUCTION

Enhanced recovery after surgery (ERAS) protocols facilitate patient recovery without increasing complication rates. An ERAS protocol designed for our liver transplant (LT) patients obtained a median hospital length of stay (LOS) of 4 days. However, a proportion of patients do not achieve early discharge. This study aimed to identify factors that predict an LOS≤ 4 days.

METHODS

Identifying factors associated with LOS <4 days in our LT patients.

RESULTS

We performed 293 LTs (2012-2021), LOS≤4 days in 171 (58.4 %). The following factors emerged as statistically predictors of LOS≤4 days in the univariate analysis: male sex, HCC or HCV patients, lower MELD score, lower BAR score, no DCD patients, shorter operative time, no intraoperative transfusion, shorter ICU stay, no Clavien-Dindo complications grade ≥ III, no primary graft dysfunction, no acute rejection, no readmission at 30 days and no retransplantation were associated to LOS≤4 days. However, in the multivariate analysis, the only independent risk factor that predicted LOS≤4 days was the presence of hepatocarcinoma. DCD donors and higher MELD score were negative factors.

CONCLUSIONS

Applying ERAS programs in LT patients is beneficial, safe and extensible to all patients, but those with hepatocarcinoma obtain higher rates of LOS≤4 days.

Challenges and opportunities in organ donation after circulatory death

In recent years, there has been resurgence in donation after circulatory death (DCD). Despite that, the number of organs transplanted from these donors remains low due to concerns about their function and a lack of an objective assessment at the time of donation. This overview examines the current DCD practices and the classification modifications to accommodate regional perspectives. Several risk factors underscore the reluctance to accept DCD organs, and we discuss the modern strategies to mitigate them. The advent of machine perfusion technology has revolutionized the field of DCD transplantation, leading to improved outcomes and better organ usage. With many strategies at our disposal, there is an urgent need for comparative trials to determine the optimal use of perfusion technologies for each donated organ type. Additional progress in defining therapeutic strategies to repair the damage sustained during the dying process should further improve DCD organ utilization and outcomes. However, there remains wide variability in access to DCD donation and transplantation, and organizational efforts should be doubled up with consensus on key ethical issues that still surround DCD donation in the era of machine perfusion.

Association of a Liver Allocation Policy Change With Domestic Travel for Liver Transplantation

Background

In 2020, liver allocation policy in the United States was changed to allow for broader organ sharing, which was hypothesized to reduce patient incentives to travel for transplant. Our objective was to describe patterns of travel for domestic liver transplant pre- and post-acuity circle (AC) implementation.

Methods

Incident adult liver transplant listings between August 16, 2016, and February 3, 2020 (pre-AC) or June 13, 2020, and December 3, 2023 (post-AC) were obtained from the Scientific Registry of Transplant Recipients. We used previously defined geographic catchment areas to classify patients as (1) no travel, (2) travel to a neighboring region, and (3) travel beyond a neighboring region. We used multinomial logistic regression to identify characteristics associated with travel and cause-specific hazards modeling to estimate the association between travel and time to deceased donor transplant, stratified by model for end-stage liver disease (MELD) score and AC era.

Results

Among 83 033 liver candidates, 76% were listed in their home region. Black race, lower educational attainment, increased neighborhood social deprivation, and Medicaid were significantly associated with decreased odds of traveling beyond a neighboring region. After AC, traveling beyond a neighboring region was associated with an increased hazard of transplant for patients with a MELD score <15 (cause-specific hazard ratio [csHR]: 1.25; 95% confidence interval [CI], 1.11-1.40), MELD score 15-24 (csHR: 1.19; 95% CI, 1.07-1.31), and MELD score 25-34 (csHR: 1.15; 95% CI, 1.01-1.32).

Conclusions

Travel frequency, geographic patterns of travel, and characteristics associated with travel were largely unchanged after AC. Changes to allocation policy alone may not equalize patient means or desire to travel for transplant care.

Enhancing the usability of older DCD donors through strategic approaches in liver transplantation in the United States

The use of older donors after circulatory death (DCD) for liver transplantation (LT) has increased over the past decade. This study examined whether outcomes of LT using older DCD (≥50 y) have improved with advancements in surgical/perioperative care and normothermic machine perfusion (NMP) technology. A total of 7602 DCD LT cases from the United Network for Organ Sharing database (2003-2022) were reviewed. The impact of older DCD donors on graft survival was assessed using the Kaplan-Meier and HR analyses. In all, 1447 LT cases (19.0%) involved older DCD donors. Although there was a decrease in their use from 2003 to 2014, a resurgence was noted after 2015 and reached 21.9% of all LTs in the last 4 years (2019-2022). Initially, 90-day and 1-year graft survivals for older DCDs were worse than younger DCDs, but this difference decreased over time and there was no statistical difference after 2015. Similarly, HRs for graft loss in older DCD have recently become insignificant. In older DCD LT, NMP usage has increased recently, especially in cases with extended donor-recipient distances, while the median time from asystole to aortic cross-clamp has decreased. Multivariable Cox regression analyses revealed that in the early phase, asystole to cross-clamp time had the highest HR for graft loss in older DCD LT without NMP, while in the later phases, the cold ischemic time (>5.5 h) was a significant predictor. LT outcomes using older DCD donors have become comparable to those from young DCD donors, with recent HRs for graft loss becoming insignificant. The strategic approach in the recent period could mitigate risks, including managing cold ischemic time (≤5.5 h), reducing asystole to cross-clamp time, and adopting NMP for longer distances. Optimal use of older DCD donors may alleviate the donor shortage.

Sequential Normothermic Regional Perfusion and End-ischemic Ex Situ Machine Perfusion Allow the Safe Use of Very Old DCD Donors in Liver Transplantation

BACKGROUND

In Italy, 20 min of continuous, flat-line electrocardiogram are required for death declaration. Despite prolonged warm ischemia time, Italian centers reported good outcomes in controlled donation after circulatory death (cDCD) liver transplantation by combining normothermic regional and end-ischemic machine perfusion (MP). The aim of this study was to evaluate the safety and feasibility of the use of septuagenarian and octogenarian cDCD donors with this approach.

METHODS

All cDCD older than 70 y were evaluated during normothermic regional perfusion and then randomly assigned to dual hypothermic or normothermic MP.

RESULTS

In the period from April 2021 to December 2022, 17 cDCD older than 70 y were considered. In 6 cases (35%), the graft was not considered suitable for liver transplantation, whereas 11 (65%) were evaluated and eventually transplanted. The median donor age was 82 y, being 8 (73%) older than 80. Median functional warm ischemia and no-flow time were 36 and 28 min, respectively. Grafts were randomly assigned to ex situ dual hypothermic oxygenated MP in 6 cases (55%) and normothermic MP in 5 (45%). None was discarded during MP. There were no cases of primary nonfunction, 1 case of postreperfusion syndrome (9%) and 2 cases (18%) of early allograft dysfunction. At a median follow-up of 8 mo, no vascular complications or ischemic cholangiopathy were reported. No major differences were found in terms of postoperative hospitalization or complications based on the type of MP.

CONCLUSIONS

The implementation of sequential normothermic regional and end-ischemic MP allows the safe use of very old donation after circulatory death donors.

Asystolic donor warm ischemia time is associated with development of postreperfusion syndrome in donation after circulatory death liver transplant

BACKGROUND

Individual events during donation after circulatory death (DCD) procurement, such as hypotensive or hypoxic warm ischemia, or circulatory arrest are all a part of donor warm ischemia time (dWIT), and may have differing effects on the outcome of the liver graft. This study aimed to identify risk factors for postreperfusion syndrome (PRS), a state of severe hemodynamic derangement following graft reperfusion, and its impact on DCD liver transplantation (LT) outcomes.

METHODS

This was a retrospective analysis using 106 DCD LT. Detailed information for events during procurement (withdrawal of life support; systolic blood pressure < 80 mmHg; oxygen saturation < 80%; circulatory arrest; aortic cold perfusion) and their association with the development of PRS were examined using logistic regression.

RESULTS

The overall incidence of PRS was 26.4%, occurring in 28 patients. Independent risk factors for PRS were asystolic dWIT (odds ratio (OR) 3.65, 95% confidence interval (CI) 1.38-9.66) and MELD score (OR 1.06, 95% CI 1.01-1.10). Total bilirubin was significantly higher in the PRS group at postoperative day (POD) 1 (p = .02; 5.2 mg/dL vs. 3.4 mg/dL), POD 3 (p = .049; 4.5 mg/dL vs. 2.8 mg/dL), and POD 7 (p = .04; 3.1 mg/dL vs. 1.9 mg/dL). Renal replacement therapy after LT was more likely to be required in the PRS group (p = .01; 48.2% vs. 23.1%).

CONCLUSION

Asystolic dWIT is a risk factor for the development of PRS in DCD LT. Our results suggest that asystolic dWIT should be considered when selecting DCD liver donors.

Current Understanding of Marginal Grafts in Liver Transplantation

End-stage liver disease (ESLD), stemming from a spectrum of chronic liver pathologies including chronic liver failure, acute cirrhosis decompensation and hepatocellular carcinoma, imposes a significant global healthcare burden. Liver transplantation (LT) remains the only treatment for ESLD. However, the escalating mortality on transplant waitlists has prompted the utilization of marginal liver grafts in LT procedures. These grafts primarily encompass elderly livers, steatotic livers, livers from donation after circulatory death, split livers and those infected with the hepatitis virus. While the expansion of the donor pool offers promise, it also introduces concomitant risks. These encompass graft failure, biliary and cardiovascular complications, the recurrence of liver disease and reduced patient and graft survival. Consequently, various established strategies, ranging from improved donor-recipient matching to surgical interventions, have emerged to mitigate these risks. This article undertakes a comprehensive assessment of the current landscape, evaluating the viability of diverse marginal liver grafts. Additionally, it synthesizes approaches aimed at enhancing the quality of such marginal liver grafts. The overarching objective is to augment the donor pool and ameliorate the risk factors associated with the shortage of liver grafts.

Donation After Circulatory Death Liver Transplantation: Early Challenges, Clinical Improvement, and Future Directions

Donation after circulatory death (DCD) liver allografts remain a widely underutilized source of donor organs for transplantation. Although initially linked with inferior outcomes, DCD liver transplant can achieve excellent patient and graft survival with suitable matching of donor and recipient characteristics, rapid donor recovery and precise donor assessment, and appropriate perioperative management. The advent of clinical liver perfusion modalities promises to redefine the viability parameters for DCD liver allografts and hopefully will encourage more widespread usage of this growing source of donor livers.

Post-transplant outcomes and financial burden of donation after circulatory death donor liver transplant after the implementation of acuity circle policy

BACKGROUND

After implementation of the Acuity Circles (AC) allocation policy, use of DCD liver grafts has increased in the United States.

METHODS

We evaluated the impact of AC on rates of DCD-liver transplants (LT), their outcomes, and medical costs in a single practice. Adult LT patients were classified into three eras: Era 1 (pre-AC, 1/01/2015-12/31/2017); Era 2 (late pre-AC era, 1/01/2018-02/03/2020); and Era 3 (AC era, 05/10/2020-09/30/2021).

RESULTS

A total of 520 eligible LTs were performed; 87 were DCD, and 433 were DBD. With each successive era, the proportion of DCD increased (Era 1: 11%; Era 2: 20%; Era 3: 24%; p < .001). DCD recipients had longer ICU stays, higher re-admission/re-operation rates, and higher incidence of ischemic cholangiopathy compared to those with DBD. Direct, surgical, and ICU costs during first admission were higher with DCD than DBD (+8.0%, p < .001; +4.2%, p < .001; and +33.3%, p = .001). DCD-related costs increased after Era 1 (Direct: +4.9% [Era 2 vs. 1] and +12.4% [Era 3 vs. 1], p = .04; Surgical: +17.7% and +21.7%, p < .001). In the AC era, there was a significantly higher proportion of donors ≥50 years, and more national organ sharing. Compared to DCD from donors <50 years, DCD from donors ≥50 years was associated with significantly higher total direct, surgical, and ICU costs (+12.6%, p = .01; +9.5%, p = .01; +84.6%, p = .03).

CONCLUSIONS

The proportion of DCD-LT, especially from older donors, has increased after the implementation of AC policies. These changes are likely to be associated with higher costs in the AC era.

British Transplantation Society guidelines on abdominal organ transplantation from deceased donors after circulatory death

The British Transplantation Society (BTS) 'Guideline on transplantation from deceased donors after circulatory death' has recently been updated and this manuscript summarises the relevant recommendations in abdominal organ transplantation from Donation after Circulatory Death (DCD) donors, encompassing the chapters on liver, kidney, pancreas and islet cell transplantation.

Screening for mitochondrial function before use-routine liver assessment during hypothermic oxygenated perfusion impacts liver utilization

BACKGROUND

To report on a concept of liver assessment during ex situ hypothermic oxygenated perfusion (HOPE) and its significant impact on liver utilization.

METHODS

An analysis of prospectively collected data on donation after circulatory death (DCD) livers, treated by HOPE at our institution, during a 11-year period between January 2012 and December 2022.

FINDINGS

Four hundred and fifteen DCD Maastricht III livers were offered during the study period in Switzerland, resulting in 249 liver transplants. Of those, we performed 158 DCD III liver transplants at our institution, with 1-year patient survival and death censored graft survival (death with functioning graft) of 87 and 89%, respectively, thus comparable to benchmark graft survivals of ideal DBD and DCD liver transplants (89% and 86%). Correspondingly, graft loss for primary non-function or cholangiopathy was overall low, i.e., 7/158 (4.4%) and 11/158 (6.9%), despite more than 82% of DCD liver grafts ranked high (6-10 points) or futile risk (>10 points) according to the UK-DCD score. Consistently, death censored graft survival was not different between low-, high-risk or futile DCD III livers. The key behind these achievements was the careful development and implementation of a routine perfusate assessment of mitochondrial biomarkers for injury and function, i.e., release of flavin mononucleotide from complex I, perfusate NADH, and mitochondrial CO2 production during HOPE, allowing a more objective interpretation of liver quality on a subcellular level, compared to donor derived data.

INTERPRETATION

HOPE after cold storage is a highly suitable and easy to perform perfusion approach, which allows reliable liver graft assessment, enabling surgeons to make a fact based decision on whether or not to implant the organ. HOPE-treatment should be combined with viability assessment particularly when used for high-risk organs, including DCD livers or organs with relevant steatosis.

FUNDING

This study was supported by the Swiss National Foundation (SNF) grant 320030_189055/1 to PD.

Should advanced donor age be a deterrent in the utilization of grafts from donation after cardiac death in deceased donor liver transplantation? The Toronto experience

BACKGROUND

Advanced donor age paired with donation after cardiac death (DCD) increases the risk of transplantation, precluding widespread use of grafts from such donors worldwide. Our aim was to analyze outcomes of liver transplantation using grafts from older DCD donors and donation after brain death (DBD) donors.

METHODS

Patients who underwent liver transplantation using grafts from deceased donors between January 2016 and December 2021 were included in the study. Short-and long-term outcomes were analyzed for 4 groups of patients: those who received DCD and DBD grafts from younger (< 50 yr) and older (≥ 50 yr) donors.

RESULTS

Of the 807 patients included in the analysis, 44.7% (n = 361) of grafts were received from older donors, with grafts for older DCD donors comprising 4.7% of the total cohort (n = 38). Patients who received grafts from older donors had a lower incidence of biliary strictures than those who received grafts from younger donors (7.9% v. 20.0% for DCD donation, p = 0.14, and 4.9% v. 6.8% for DBD donation, p = 0.34), with a significantly lower incidence of ischemic-type biliary strictures in patients who received grafts from older versus younger DCD donors (2.6% v. 18.0%, p = 0.04). There was no difference in 1- and 3-year graft survival rates among patients who received grafts from older and younger DCD donors (92.1% v. 90.8% and 80.2% v. 80.9%, respectively) and those who received grafts from older and younger DBD donors (90.1% v. 93.2% and 85.3% v. 84.4%, respectively) (p = 0.85). Pretransplantation admission to the intensive care unit (hazard ratio [HR] 9.041, p < 0.001) and nonalcoholic steatohepatitis (HR 2.197, p = 0.02) were found to significantly affect survival of grafts from older donors.

CONCLUSION

Donor age alone should not be the criterion to determine the acceptability of grafts in liver transplantation. With careful selection criteria, older DCD donors could make a valuable contribution to expanding the liver donor pool, with grafts that produce comparable results to those obtained with standard-criteria grafts.

Beyond the Concepts of Elder and Marginal in DCD Liver Transplantation: A Prospective Observational Matched-Cohort Study in the Italian Clinical Setting

Donation after circulatory determination of death (DCD) is a valuable strategy to increase the availability of grafts for liver transplantation (LT). As the average age of populations rises, the donor pool is likely to be affected by a potential increase in DCD donor age in the near future. We conducted a prospective cohort study to evaluate post-transplantation outcomes in recipients of grafts from elderly DCD donors compared with younger DCD donors, and elderly donors after brainstem determination of death (DBD). From August 2020 to May 2022, consecutive recipients of deceased donor liver-only transplants were enrolled in the study. DCD recipients were propensity score matched 1:3 to DBD recipients. One-hundred fifty-seven patients were included, 26 of whom (16.6%) were transplanted with a DCD liver graft. After propensity score matching and stratification, three groups were obtained: 15 recipients of DCD donors ≥75 years, 11 recipients of DCD donors <75 years, and 28 recipients of DBD donors ≥75 years. Short-term outcomes, as well as 12 months graft survival rates (93.3%, 100%, and 89.3% respectively), were comparable among the groups. LT involving grafts retrieved from very elderly DCD donors was feasible and safe in an experienced high-volume center, with outcomes comparable to LTs from younger DCD donors and age-matched DBD donors.

Center expansion of liver transplants using donation after circulatory death organs is associated with reduced overall waitlist mortality

INTRODUCTION

Waitlist outcomes in liver transplantation (LT) for individual recipients are improved by use of allografts procured through donation after circulatory death (DCD). However, the impact of increased DCD acceptance on overall center outcomes is unknown.

METHODS

Using the United Network for Organ Sharing database, 88 centers performing an average of ≥10 LTs/year between 1/2004 and 12/2019 were compared by percent DCD use quartile and categorized into four phenotypes according to temporal usage trends. Overall center median Model for End-stage Liver Disease at LT (MMaT), waitlist mortality, and waiting time were evaluated.

RESULTS

The overall DCD rate was 6.1% (N = 4906/80,709), ranging from 0% to 25.5%. Centers in the top DCD use quartile had lower MMaT (24 vs. 26; p < .001) and shorter overall waiting times (median 66 days vs. 90 days; p < .001) compared to bottom quartile centers. MMaT increased less over time at centers with increasing DCD use and was lower than at centers with declining DCD use (27 vs. 32; p = .017). Overall waitlist mortality between 2016 and 2019 was lower at increasing DCD use centers (17.8% vs. 22.5%, p = .034), yet did not affect 1-year mortality (p = .747).

CONCLUSIONS

The improved waitlist outcomes at centers with expanded DCD use extend beyond DCD recipients alone without negative consequences to overall post-LT center metrics.

Bioenergetic and Cytokine Profiling May Help to Rescue More DCD Livers for Transplantation

The majority of organs used for liver transplantation come from brain-dead donors (DBD). In order to overcome the organ shortage, increasingly donation after circulatory death (DCD) organs are also considered. Since normothermic machine perfusion (NMP) restores metabolic activity and allows for in-depth assessment of organ quality and function prior to transplantation, such organs may benefit from NMP. We herein compare the bioenergetic performance through a comprehensive evaluation of mitochondria by high-resolution respirometry in tissue biopsies and the inflammatory response in DBD and DCD livers during NMP. While livers were indistinguishable by perfusate biomarker assessment and histology, our findings revealed a greater impairment of mitochondrial function in DCD livers after static cold storage compared to DBD livers. During subsequent NMPs, DCD organs recovered and eventually showed a similar performance as DBD livers. Cytokine expression analysis showed no differences in the early phase of NMP, while towards the end of NMP, significantly elevated levels of IL-1β, IL-5 and IL-6 were found in the perfusate of DCD livers. Based on our results, we find it worthwhile to reconsider more DCD organs for transplantation to further extend the donor pool. Therefore, donor organ quality criteria must be developed, which may include an assessment of bioenergetic function and cytokine quantification.

Outcomes Of Lung And Liver Transplantation After Simultaneous Recovery Using Abdominal Normothermic Regional Perfusion In Donors After The Circulatory Determination Of Death Versus Donors After Brain Death

Normothermic regional perfusion (NRP) in controlled donation after the circulatory determination of death (cDCD) is a growing preservation technique for abdominal organs that coexists with the rapid recovery of lungs. We aim at describing the outcomes of lung transplants (LuTx) and liver transplants (LiTx) when both grafts are simultaneously recovered from cDCD donors using NRP, and compare them to donation after brain death (DBD). All LuTx and LiTx meeting these criteria during January-2015 to December-2020 in Spain were included in the study. Simultaneous recovery of lungs and livers was undertaken in 227 (17%) cDCD with NRP and 1,879 (21%) DBD donors (p<0.001). Primary graft dysfunction grade-3 within the first 72hours was similar in both LuTx groups (14.7% cDCD vs. 10.5% DBD;p=0.139). LuTx survival at 1 and 3years was 79.9% and 66.4% in cDCD, vs. 81.9% and 69.7% in DBD (p=0.403). The incidence of primary non-function and ischemic cholangiopathy was similar in both LiTx groups. Graft survival at 1 and 3years was 89.7% and 80.8% in cDCD vs. 88.2% and 82.1% in DBD LiTx (p=0.669). In conclusion, the simultaneous rapid recovery of lungs and preservation of abdominal organs with NRP in cDCD donors is feasible, and offers similar outcomes in both LuTx and LiTx recipients to transplants using DBD grafts.

Machine Perfusion for Extended Criteria Donor Livers: What Challenges Remain?

Based on the renaissance of dynamic preservation techniques, extended criteria donor (ECD) livers reclaimed a valuable eligibility in the transplantable organ pool. Being more vulnerable to ischemia, ECD livers carry an increased risk of early allograft dysfunction, primary non-function and biliary complications and, hence, unveiled the limitations of static cold storage (SCS). There is growing evidence that dynamic preservation techniques—dissimilar to SCS—mitigate reperfusion injury by reconditioning organs prior transplantation and therefore represent a useful platform to assess viability. Yet, a debate is ongoing about the advantages and disadvantages of different perfusion strategies and their best possible applications for specific categories of marginal livers, including organs from donors after circulatory death (DCD) and brain death (DBD) with extended criteria, split livers and steatotic grafts. This review critically discusses the current clinical spectrum of livers from ECD donors together with the various challenges and posttransplant outcomes in the context of standard cold storage preservation. Based on this, the potential role of machine perfusion techniques is highlighted next. Finally, future perspectives focusing on how to achieve higher utilization rates of the available donor pool are highlighted.

Lost potential and missed opportunities for DCD liver transplantation in the United States

BACKGROUND

Donation after cardiac death(DCD) has been proposed as an avenue to expand the liver donor pool.

METHODS

We examined factors associated with nonrecovery of DCD livers using UNOS data from 2015 to 2019.

RESULTS

There 265 non-recovered potential(NRP) DCD livers. Blood type AB (7.8% vs. 1.1%) and B (16.9% vs. 9.8%) were more frequent in the NRP versus actual donors (p < 0.001). The median driving time between donor hospital and transplant center was similar for NRP and actual donors (30.1 min vs. 30.0 min; p = 0.689), as was the percentage located within a transplant hospital (20.8% vs. 20.9%; p = 0.984).The donation service area(DSA) of a donor hospital explained 27.9% (p = 0.001) of the variability in whether a DCD liver was recovered.

CONCLUSION

A number of potentially high quality DCD donor livers go unrecovered each year, which may be partially explained by donor blood type and variation in regional and DSA level practice patterns.

Protective mechanisms and current clinical evidence of hypothermic oxygenated machine perfusion (HOPE) in preventing post-transplant cholangiopathy

The development of cholangiopathies after liver transplantation impacts on the quality and duration of graft and patient survival, contributing to higher costs as numerous interventions are required to treat strictures and infections at the biliary tree. Prolonged donor warm ischaemia time in combination with additional cold storage are key risk factors for the development of biliary strictures. Based on this, the clinical implementation of dynamic preservation strategies is a current hot topic in the field of donation after circulatory death (DCD) liver transplantation. Despite various retrospective studies reporting promising results, also regarding biliary complications, there are only a few randomised-controlled trials on machine perfusion. Recently, the group from Groningen has published the first randomised-controlled trial on hypothermic oxygenated perfusion (HOPE), demonstrating a significant reduction of symptomatic ischaemic cholangiopathies with the use of a short period of HOPE before DCD liver implantation. The most likely mechanism for this important effect, also shown in several experimental studies, is based on mitochondrial reprogramming under hypothermic aerobic conditions, e.g. exposure to oxygen in the cold, with a controlled and slow metabolism of ischaemically accumulated succinate and simultaneous ATP replenishment. This unique feature prevents mitochondrial oxidative injury and further downstream tissue inflammation. HOPE treatment therefore supports livers by protecting them from ischaemia-reperfusion injury (IRI), and thereby also prevents the development of post-transplant biliary injury. With reduced IRI-associated inflammation, recipients are also protected from activation of the innate immune system, with less acute rejections seen after HOPE.

Disparities in the Use of Older Donation After Circulatory Death Liver Allografts in the United States Versus the United Kingdom

BACKGROUND

This study aimed to assess the differences between the United States and the United Kingdom in the characteristics and posttransplant survival of patients who received donation after circulatory death (DCD) liver allografts from donors aged >60 y.

METHODS

Data were collected from the UK Transplant Registry and the United Network for Organ Sharing databases. Cohorts were dichotomized into donor age subgroups (donor >60 y [D >60]; donor ≤60 y [D ≤60]). Study period: January 1, 2001, to December 31, 2015.

RESULTS

1157 DCD LTs were performed in the United Kingdom versus 3394 in the United States. Only 13.8% of US DCD donors were aged >50 y, contrary to 44.3% in the United Kingdom. D >60 were 22.6% in the United Kingdom versus 2.4% in the United States. In the United Kingdom, 64.2% of D >60 clustered in 2 metropolitan centers. In the United States, there was marked inter-regional variation. A total of 78.3% of the US DCD allografts were used locally. One- and 5-y unadjusted DCD graft survival was higher in the United Kingdom versus the United States (87.3% versus 81.4%, and 78.0% versus 71.3%, respectively; P < 0.001). One- and 5-y D >60 graft survival was higher in the United Kingdom (87.3% versus 68.1%, and 77.9% versus 51.4%, United Kingdom versus United States, respectively; P < 0.001). In both groups, grafts from donors ≤30 y had the best survival. Survival was similar for donors aged 41 to 50 versus 51 to 60 in both cohorts.

CONCLUSIONS

Compared with the United Kingdom, older DCD LT utilization remained low in the United States, with worse D >60 survival. Nonetheless, present data indicate similar survivals for older donors aged ≤60, supporting an extension to the current US DCD age cutoff.

The volume - Outcomes relationship in donation after circulatory death liver transplantation

Background

Donation after circulatory death (DCD) liver transplantation (LT) has become an effective mechanism for expanding the donor pool and decreasing waitlist mortality. However, it is unclear if low‐volume DCD centers can achieve comparable outcomes to high‐volume centers.

Methods

From 2011 to 2019 utilizing the United Network for Organ Sharing (UNOS) database, liver transplant centers were categorized into tertiles based on their annual volume of DCD LTs. Donor selection, recipient selection, and survival outcomes were compared between very‐low volume (VLV, n = 1–2 DCD LTs per year), low‐volume (LV, n = 3–5), and high‐volume (HV, n > 5) centers.

Results

One hundred and ten centers performed 3273 DCD LTs. VLV‐centers performed 339 (10.4%), LV‐centers performed 627 (19.2%), and HV‐centers performed 2307 (70.4%) LTs. 30‐day, 90‐day, and 1‐year patient and graft survival were significantly increased at HV‐centers (all P < .05). Recipients at HV‐centers had shorter waitlist durations (P < .01) and shorter hospital lengths of stay (P < .01). On multivariable regression, undergoing DCD LT at a VLV‐center or LV‐center was associated with increased 1‐year patient mortality (VLV‐OR:1.73, 1.12–2.69) (LV‐OR: 1.42, 1.01–2.00) and 1‐year graft failure (VLV‐OR: 1.79, 1.24–2.58) (LV‐OR: 1.28, .95–1.72).

Discussion

Increased annual DCD liver transplant volume is associated with improved patient and graft survival.

Abdominal normothermic regional perfusion in controlled donation after circulatory determination of death liver transplantation: Outcomes and risk factors for graft loss

Postmortem normothermic regional perfusion (NRP) is a rising preservation strategy in controlled donation after circulatory determination of death (cDCD). Herein, we present results for cDCD liver transplants performed in Spain 2012-2019, with outcomes evaluated through December 31, 2020. Results were analyzed retrospectively and according to recovery technique (abdominal NRP [A-NRP] or standard rapid recovery [SRR]). During the study period, 545 cDCD liver transplants were performed with A-NRP and 258 with SRR. Median donor age was 59 years (interquartile range 49-67 years). Adjusted risk estimates were improved with A-NRP for overall biliary complications (OR 0.300, 95% CI 0.197-0.459, p < .001), ischemic type biliary lesions (OR 0.112, 95% CI 0.042-0.299, p < .001), graft loss (HR 0.371, 95% CI 0.267-0.516, p < .001), and patient death (HR 0.540, 95% CI 0.373-0.781, p = .001). Cold ischemia time (HR 1.004, 95% CI 1.001-1.007, p = .021) and re-transplantation indication (HR 9.552, 95% CI 3.519-25.930, p < .001) were significant independent predictors for graft loss among cDCD livers with A-NRP. While use of A-NRP helps overcome traditional limitations in cDCD liver transplantation, opportunity for improvement remains for cases with prolonged cold ischemia and/or technically complex recipients, indicating a potential role for complimentary ex situ perfusion preservation techniques.

Development of a Novel Prognostic Nomogram for High Model for End-Stage Liver Disease Score Recipients Following Deceased Donor Liver Transplantation

Background

A high model of end-stage liver disease (MELD) score (>30) adversely affects outcomes even if patients receive prompt liver transplantation (LT). Therefore, balanced allocation of donor grafts is indispensable to avoid random combinations of donor and recipient risk factors, which often lead to graft or recipient loss. Predictive models aimed at avoiding donor risk factors in high-MELD score recipients are urgently required to obtain satisfactory outcomes.

Method

Data of patients with MELD score >30 who underwent LT at three transplantation institutes between 2015 and 2018 were retrospectively reviewed. Early allograft dysfunction (EAD), length of intensive care unit (ICU) stay, and graft loss were recorded. Corresponding independent risk factors were analyzed using stepwise multivariable regression analysis. A prediction model of graft loss was developed, and discrimination and calibration were measured.

Results

After applying the exclusion criteria, 778 patients were enrolled. The incidence of EAD was 34.8% (271/778). Donor graft macrovesicular steatosis, graft-to-recipient weight ratio (GRWR), warm ischemia time (WIT), cold ischemia time (CIT), and ABO blood incompatibility, together with donor serum albumins, were independent predictors of EAD. The incidence of ICU stay over 10 days was 64.7% (503/778). Donor age, recipient's MELD score, Child score, and CIT were independent predictors of ICU stay. The 3-year graft survival rates (GSRs) in the training and validation cohorts were 64.2 and 59.3%, respectively. The independent predictors of graft loss were recipient's Child score, ABO blood type incompatibility, donor serum total bilirubin over 17.1 μmol/L, and cold CIT. A nomogram based on these variables was internally and externally validated and showed good performance (area under the receiver operating characteristic curve = 70.8 and 66.0%, respectively). For a recipient with a high MELD score, the avoidance of ABO blood type incompatibility and CIT ≥6 h would achieve a 3-year GSR of up to 78.4%, whereas the presence of the aforementioned risk factors would decrease the GSR to 35.4%.

Conclusion

The long-term prognosis of recipients with MELD scores >30 could be greatly improved by avoiding ABO blood type incompatibility and CIT ≥6 h.

Temporal Trends in Utilization and Outcomes of DCD Livers in the United States

BACKGROUND

Historically, donation after circulatory death (DCD) livers were frequently discarded because of higher mortality and graft loss after liver transplantation (LT). However, the demand for LT continues to outstrip the supply of "acceptable" organs. Additionally, changes in the donor pool, organ allocation, and clinical management of donors and recipients, and improved clinical protocols might have altered post-DCD-LT outcomes.

METHODS

We studied 5975 recovered DCD livers using US Scientific Registry of Transplant Recipients data from 2005 to 2017, with a comparison group of 78 235 adult donation after brain death (DBD) livers recovered during the same time period. We quantified temporal trends in discard using adjusted multilevel logistic regression and temporal trends in post-LT mortality and graft loss for DCD LT recipients using adjusted Cox regression.

RESULTS

DCD livers were more likely to be discarded than DBD livers across the entire study period, and the relative likelihood of discard increased over time (adjusted odds ratio [aOR] of discard DCD versus DBD 3.854.455.14 2005-2007, 5.225.876.59 2015-2017) despite improving outcomes after DCD LT. Mortality risk for DCD LTs decreased in each time period (compared with 2005-2007, aHR 2008-2011 0.720.840.97, aHR 2012-2014 0.480.580.70, aHR 2015-2017 0.340.430.55), as did risk of graft loss (compared with 2005-2007, aHR 2008-2011 0.690.810.94, aHR 2012-2014 0.450.550.67, aHR 2015-2017 0.360.450.56).

CONCLUSIONS

Despite dramatic improvements in outcomes of DCD LT recipients, DCD livers remain substantially more likely to be discarded than DBD livers, and this discrepancy has actually increased over time. DCD livers are underutilized and have the potential to expand the donor pool.

A multicentre outcome analysis to define global benchmarks for donation after circulatory death liver transplantation

BACKGROUND & AIMS

The concept of benchmarking is established in the field of transplant surgery; however, benchmark values for donation after circulatory death (DCD) liver transplantation are not available. Thus, we aimed to identify the best possible outcomes in DCD liver transplantation and to propose outcome reference values.

METHODS

Based on 2,219 controlled DCD liver transplantations, collected from 17 centres in North America and Europe, we identified 1,012 low-risk, primary, adult liver transplantations with a laboratory MELD score of ≤20 points, receiving a DCD liver with a total donor warm ischemia time of ≤30 minutes and asystolic donor warm ischemia time of ≤15 minutes. Clinically relevant outcomes were selected and complications were reported according to the Clavien-Dindo-Grading and the comprehensive complication index (CCI). Corresponding benchmark cut-offs were based on median values of each centre, where the 75^th-percentile was considered.

RESULTS

Benchmark cases represented between 19.7% and 75% of DCD transplantations in participating centres. The 1-year retransplant and mortality rates were 4.5% and 8.4% in the benchmark group, respectively. Within the first year of follow-up, 51.1% of recipients developed at least 1 major complication (≥Clavien-Dindo-Grade III). Benchmark cut-offs were ≤3 days and ≤16 days for ICU and hospital stay, ≤66% for severe recipient complications (≥Grade III), ≤16.8% for ischemic cholangiopathy, and ≤38.9 CCI points 1 year after transplant. Comparisons with higher risk groups showed more complications and impaired graft survival outside the benchmark cut-offs. Organ perfusion techniques reduced the complications to values below benchmark cut-offs, despite higher graft risk.

CONCLUSIONS

Despite excellent 1-year survival, morbidity in benchmark cases remains high. Benchmark cut-offs targeting morbidity parameters offer a valid tool to assess the protective value of new preservation technologies in higher risk groups and to provide a valid comparator cohort for future clinical trials.

LAY SUMMARY

The best possible outcomes after liver transplantation of grafts donated after circulatory death (DCD) were defined using the concept of benchmarking. These were based on 2,219 liver transplantations following controlled DCD donation in 17 centres worldwide. Donor and recipient combinations with higher risk had significantly worse outcomes. However, the use of novel organ perfusion technology helped high-risk patients achieve similar outcomes as the benchmark cohort.

Similar Results in Liver Transplantation From Controlled Donation After Circulatory Death Donors With Normothermic Regional Perfusion and Donation After Brain Death Donors: A Case-Matched Single-Center Study

Although good results have been reported with the use of normothermic regional perfusion (NRP) in controlled donation after circulatory death (cDCD) liver transplantation (LT), there is a lack of evidence to demonstrate similar results to donation after brain death (DBD). We present a single-center retrospective case-matched (1:2) study including 100 NRP cDCD LTs and 200 DBD LTs and a median follow-up of 36 months. Matching was done according to donor age, recipient Model for End-Stage Liver Disease score, and cold ischemia time. The following perioperative results were similar in both groups: alanine transaminase peaks of 909 U/L in the DBD group and 836 U/L in the cDCD group and early allograft disfunction percentages of 21% and 19.2%, respectively. The 1-year and 3-year overall graft survival for cDCD was 99% and 93%, respectively, versus 92% and 87%, respectively, for DBD (P = 0.04). Of note, no cases of primary nonfunction or ischemic-type biliary lesion were observed among the cDCD grafts. Our results confirm that NRP cDCD LT meets the same outcomes as those obtained with DBD LT and provides evidence to support the idea that cDCD donors per se should no longer be considered as "marginal donors" when recovered with NRP.

Recommendations for Donor and Recipient Selection and Risk Prediction: Working Group Report From the ILTS Consensus Conference in DCD Liver Transplantation

Although the utilization of donation after circulatory death donors (DCDs) for liver transplantation (LT) has increased steadily, much controversy remains, and no common acceptance criteria exist with regard to donor and recipient risk factors and prediction models. A consensus conference was organized by International Liver Transplantation Society on January 31, 2020, in Venice, Italy, to review the current clinical practice worldwide regarding DCD-LT and to develop internationally accepted guidelines. The format of the conference was based on the grade system. International experts in this field were allocated to 6 working groups and prepared evidence-based recommendations to answer-specific questions considering the currently available literature. Working group members and conference attendees served as jury to edit and confirm the final recommendations presented at the end of the conference by each working group separately. This report presents the final statements and recommendations provided by working group 2, covering the entire spectrum of donor and recipient risk factors and prediction models in DCD-LT.

Early Allograft Dysfunction and Complications in DCD Liver Transplantation: Expert Consensus Statements From the International Liver Transplantation Society

Livers for transplantation from donation after circulatory death donors are relatively more prone to early and ongoing alterations in graft function that might ultimately lead to graft loss and even patient death. In consideration of this fact, this working group of the International Liver Transplantation Society has performed a critical evaluation of the medical literature to create a set of statements regarding the assessment of early allograft function/dysfunction and complications arising in the setting of donation after circulatory death liver transplantation.

Comparable graft survival is achievable with the usage of donation after circulatory death liver grafts from donors at or above 70 years of age: A long-term UK national analysis

The aim of the study was to assess the UK donation after circulatory death (DCD) liver transplant experience from donors ≥70 years. Nationwide UK DCD retrospective analysis was conducted between 2001 and 2015 (n = 1163). Recipients were divided into group 1 vs. group 2 (donors 70≥ vs. <70 years, respectively). group 1 (n = 69, 5.9%) recipients were older (median 59 vs. 55 years, p = .001) and had longer waitlist time (128 vs. 84 days; p = .039). 94.2% of group 1 clustered in London and Birmingham, where the two busiest centers are located. group 1 allografts had higher UKDRI and UK DCD Risk Scores but similar WIT and CIT and were more likely to have been imported. Both groups had similar 1-, 3-, and 5-year graft survival (group 1, 90%, 81.4%, and 74% vs. group 2, 88.6%, 81.4%, and 78.6%, respectively; p = .54). Both groups had similar ICU stay length (p = .22), 3-month hepatic artery thrombosis rates (4.4% vs 4.0%; p = .9), and 12-month readmission rates for all biliary complications (20.3% vs 25.7%; p = .32). This study demonstrates that acceptable outcomes are achievable using older grafts in a highly selected cohort at experienced centers. Advanced age should not be an absolute contraindication to utilizing a DCD graft from donors aged ≥70 years.

Expanding Role of Donation After Circulatory Death Donors in Liver Transplantation

Better understanding of how to utilize donation after circulatory death (DCD) liver grafts has resulted in improved national outcomes and expansion in the number of DCD liver transplants (LTs). This improvement has been driven by better donor and recipient matching, careful evaluation of hemodynamics during withdrawal of life support, and refinement of the procurement operation. Changes to liver allocation likely will result in increased utilization of DCD liver grafts. Ischemic cholangiopathy remains the Achilles heel of DCD LTs and, although rates have fallen with improved protocols, a certain rate likely is unavoidable. This review discusses contemporary issues with DCD LTs.

Simultaneous liver-kidney transplantation from donation after cardiac death donors: an updated perspective

Outcomes of both donation after cardiac death (DCD) liver and kidney transplants are improving. Experience in simultaneous liver-kidney transplant (SLK) using DCD donors, however, remains limited. In an updated cohort (2010-2018), outcomes of 30 DCD SLK and 131 donation after brain death (DBD) SLK from Mayo Clinic Arizona and Mayo Clinic Minnesota were reviewed. The Model for End-Stage Liver Disease score was lower in the DCD SLK group (23 vs 29, P = .01). Kidney delayed graft function (DGF) rates were similar between the 2 groups (P = .11), although the duration of DGF was longer for DCD SLK recipients (20 vs 4 days, P = .01). Liver allograft (93.3% vs 93.1%, P = .29), kidney allograft (93.3% vs 93.1%, P = .91), and patient (96.7% vs 95.4%, P = .70) 1-year survival rates were similar. At 1 year, there were no differences in the estimated glomerular filtration rate (57.7 ± 18.2 vs 56.3 ± 17.7, P = .75) or progression of fibrosis (ci) on protocol kidney biopsy (P = .67). A higher incidence of biliary complications was observed in the DCD SLK group, with ischemic cholangiopathy being the most common (10.0% vs 0.0%, P = .03). The majority of biliary complications resolved with endoscopic management. With appropriate selection, DCD SLK recipients can have results equivalent to those of DBD SLK recipients.

Expanding the donor pool for liver transplantation with marginal donors

The current supply of acceptable donor livers is not sufficient to meet the demands of listed patients awaiting transplantation resulting in thousands of deaths each year. Increased utilization of marginal livers may help alleviate this supply/demand mismatch by expanding the donor liver pool. The current status of liver transplantation using marginal donor grafts and efforts to optimize usage are discussed with attention to elderly donors, steatotic livers, donors after circulatory death, and split liver grafts.

Biliary complications in donation after circulatory death liver transplantation: the Australian National Liver Transplantation Unit's experience

BACKGROUND

Biliary complications are the most common complications of donation after circulatory death (DCD) liver transplantation and the international experience with DCD transplants suggests increased rates of biliary complications compared to donation after brain death transplants. Therefore, it is important to understand factors that are associated with the development of biliary complications within the Australian DCD context in order to inform future practice. The aim of this study is to determine the incidence of biliary complications after DCD liver transplantation at the Australian National Liver Transplantation Unit and identify factors associated with this outcome.

METHODS

A retrospective analysis of all adult DCD liver transplants at the Australian National Liver Transplantation Unit from 2007 to 2015 was undertaken. The primary outcome measure was the incidence of biliary complications and was censored on 31 December 2016. Recipients were then stratified into groups based on the development of biliary complications and risk factor analysis was performed.

RESULTS

Biliary complications occurred in 35% of DCD transplants, including seven anastomotic strictures and 10 non-anastomotic strictures. Higher donor risk index scores (P = 0.03), post-transplant portal vein complications (P = 0.042) and peak gamma-glutamyl transferase levels within 7 days post-transplant (P = 0.047) were associated with biliary complications.

CONCLUSION

Findings from this study demonstrate that biliary complications remain common in DCD liver recipients. Recipients who developed a biliary complication tended to have higher donor risk index, elevated peak gamma-glutamyl transferase levels within 7 days post-transplant or a portal vein complication. The presence of any of these factors should prompt close monitoring for post-transplant biliary complications.

Perioperative and long-term outcomes of utilizing donation after circulatory death liver grafts with macrosteatosis: A multicenter analysis

BACKGROUND

Given the potentially additive risk from using donor livers that are both steatotic and from a donation after circulatory death (DCD) donor, there is a paucity of data on the outcome of DCD liver transplantation (LT) utilizing livers with macrosteatosis.

METHODS

All DCD LT performed at Mayo Clinic-Florida, Mayo Clinic-Arizona, and Mayo Clinic-Rochester from 1999 to 2019 were included (N = 714). Recipients of DCD LT were divided into 3 groups: those with moderate macrosteatosis (30%-60%), mild macrosteatosis (5%-30%), and no steatosis (<5%).

RESULTS

Patients with moderate macrosteatosis had a higher rate of postreperfusion syndrome (PRS; 53.9% vs 26.2%; P = .002), postreperfusion cardiac arrest (7.7% vs 0.3%; P < .001), primary nonfunction (PNF; 7.7% vs 1.0%; P = .003), early allograft dysfunction (EAD; 70.8% vs 45.6% and 8.3%; P = .02), and acute kidney injury (AKI; 39.1% vs 19.4%; P = .02) than patients with no steatosis. No difference in any of the perioperative complications was seen between the mild macrosteatosis and the no steatosis groups except for the rate of EAD (56.8% vs 45.6%; P = .04). No difference in ischemic cholangiopathy (IC), vascular thrombosis/stenosis or graft, and patient survival was seen between the 3 groups.

CONCLUSION

DCD donors with mild macrosteatosis < 30% can be utilized with no increase in perioperative complications and similar patient and graft survival compared to DCD donors with no steatosis. When utilizing DCD donors with moderate macrosteatosis higher rates of PRS, PNF, postreperfusion cardiac arrest, EAD, and AKI should be anticipated.

Proceedings of the 25th Annual Congress of the International Liver Transplantation Society

The 25th Annual Congress of the International Liver Transplantation Society was held in Toronto, Canada, from May 15 to 18, 2019. Surgeons, hepatologists, anesthesiologists, critical care intensivists, radiologists, pathologists, and research scientists from all over the world came together with the common aim of improving care and outcomes for liver transplant recipients and living donors. Some of the featured topics at this year's conference included multidisciplinary perioperative care in liver transplantation, worldwide approaches to organ allocation, donor steatosis, and updates in pediatrics, immunology, and radiology. This report presents excerpts and highlights from invited lectures and select abstracts, reviewed and compiled by the Vanguard Committee of International Liver Transplantation Society. This will hopefully contribute to further advances in clinical practice and research in liver transplantation.

Donation after circulatory death liver transplantation: consensus statements from the Spanish Liver Transplantation Society

Livers from donation after circulatory death (DCD) donors are an increasingly more common source of organs for transplantation. While there are few high-level studies in the field of DCD liver transplantation, clinical practice has undergone progressive changes during the past decade, in particular due to mounting use of postmortem normothermic regional perfusion (NRP). In Spain, uncontrolled DCD has been performed since the late 1980s/early 1990s, while controlled DCD was implemented nationally in 2012. Since 2012, the rise in DCD liver transplant activity in Spain has been considerable, and the great majority of DCD livers transplanted in Spain today are recovered with NRP. A panel of the Spanish Liver Transplantation Society was convened in 2018 to evaluate current evidence and accumulated experience in DCD liver transplantation, in particular addressing issues related to DCD liver evaluation, acceptance criteria, and recovery as well as recipient selection and postoperative management. This panel has created a series of consensus statements for the standard of practice in Spain and has published these statements with the hope they might help guide other groups interested in implementing new forms of DCD liver transplantation and/or introducing NRP into their clinical practices.

The Changing Landscapes in DCD Liver Transplantation

Purpose of Review

The transplant community continues to look for ways to help address the discordance between donor liver graft availability and patients on the liver transplant waiting list. Donation after circulatory death (DCD) donor livers represents one potential means to help address this discordance. The present review describes the changing landscape of DCD liver transplantation (LT).

Recent Findings

The number of DCD LTs performed annually within the USA has continued to grow on an annual basis. Importantly, national data has demonstrated that outcomes with DCD LT have been improving. This improvement has been driven by better understanding of how to successfully utilize these organs through better donor and recipient matching and careful evaluation of both hemodynamics during withdrawal of life support and the refinement of the procurement operation.

Summary

Despite these improvements in outcome, ischemic cholangiopathy (IC) continues to be the Achilles heel of DCD LT. Emerging technologies such as various forms of machine perfusion may allow for reduction of complications and better prognostication of the risk associated with DCD liver grafts.

Liver graft from donation after circulatory death donor: Real practice to improve graft viability

Donation after circulatory death (DCD) is an increasing source of liver grafts for transplantation, yet outcomes have been inferior compared to donation after brain death liver transplantation. These worse outcomes are mainly due to the severe graft injury resulting from mandatory warm ischemia during DCD organ recovery. New evidence, however, indicates that improved donor selection and surgical techniques can decrease the risk of graft failure and ischemic cholangiopathy (IC). Under current best practices, DCD organs are retrieved with the super-rapid technique, optimizing timing and protecting the liver graft from detrimental warm ischemia. Graft viability is influenced by both the quantity and quality of warm ischemia, which is unique to each donor and causes various degrees of pathophysiologic consequences. Evidence also shows that the choice of preservation solution and premortem heparin administration influences graft viability. Additionally, although the precise mechanism of IC remains unknown, stasis of blood during donor warm ischemia may cause the formation of microthrombi in the peribiliary vascular plexus and ischemia of the bile duct. Importantly, thrombolytic protocols show a possible preventive modality for IC. Finally, while ex vivo machine perfusion technology has gained an interest in DCD liver transplantation, further studies are necessary to evaluate the effectiveness of this evolving field to improve graft quality and transplant outcomes.

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.

Does Normothermic Regional Perfusion Improve the Results of Donation After Circulatory Death Liver Transplantation?

BACKGROUND

The so-called grafts or donors with extended criteria are a risk factor for the development of liver transplant activity. One source comes from controlled donation after circulatory death (cDCD). The hypothesis was to verify the improvement in results by comparing DCD liver transplants performed with postmortem normothermic regional perfusion (NRP) vs super-rapid recovery (SRR), the current standard for cDCD. A prospective study comparing both techniques was carried out.

METHODS

A total of 42 transplants were performed with cDCD, 22 of which were with SRR and 23 with NRP from April 2014 to September 2019.

RESULTS

Differences were found in early allograft dysfunction (68.1% in the SRR group vs 25% in the NRP group; P < .01) and biliary complications (22.7% vs 5%, respectively; P = .04). Differences were also found, although not statistically significant, in ischemic cholangiopathy (13.6% in the SRR group vs 5% in the NRP group; P = .09), and retransplant rate (9.1% vs 0%, respectively; P = .3).

CONCLUSIONS

With the use of NRP machines, results are similar to the standard donation with donors in brain death in terms of rate of early allograft dysfunction and survival of the patient and graft attempted, reducing the rate of ischemic cholangiopathy compared with SRR.

Controlled donation after circulatory death up to 80 years for liver transplantation: Pushing the limit again

Our main objective was to compare liver transplant (LT) results between donation after circulatory death (DCD) and donation after brainstem death (DBD) in our hospital and to analyze, within the DCD group, the influence of age on the results obtained with DCD donors aged >70 years and up to 80 years. All DCD-LTs performed were analyzed prospectively. The results of the DCD group were compared with those of a control group who received a DBD-LT immediately after each DCD-LT. Later, the results obtained within the DCD group were analyzed according to the age of the donors, considering 2 subgroups with a cut-off point at 70 years. Survival results for LT with DCD and super rapid recovery were not inferior to those obtained in a similar group of patients transplanted with DBD livers. However, the cost of DCD was a higher rate of biliary complications, including ischemic cholangiopathy. Donor age was not a negative factor.

Machine perfusion strategies in liver transplantation

Machine perfusion is a hot topic in liver transplantation and several new perfusion concepts are currently developed. Prior to introduction into routine clinical practice, however, such perfusion approaches need to demonstrate their impact on liver function, post-transplant complications, utilization rates of high-risk organs, and cost benefits. Therefore, based on results of experimental and clinical studies, the community has to recognize the limitations of this technology. In this review, we summarize current perfusion concepts and differences between protective mechanisms of ex- and in-situ perfusion techniques. Next, we discuss which graft types may benefit most from perfusion techniques, and highlight the current understanding of liver viability testing. Finally, we present results from recent clinical trials involving machine liver perfusion, and analyze the value of different outcome parameters, currently used as endpoints for randomized controlled trials in the field.

Clinical Implications of Donor Warm and Cold Ischemia Time in Donor After Circulatory Death Liver Transplantation

The use of donation after circulatory death (DCD) liver allografts has been constrained by limitations in the duration of donor warm ischemia time (DWIT), donor agonal time (DAT), and cold ischemia time (CIT). The purpose of this study is to assess the impact of longer DWIT, DAT, and CIT on graft survival and other outcomes in DCD liver transplants. The Scientific Registry of Transplant Recipients was queried for adult liver transplants from DCD donors between 2009 and 2015. Donor, recipient, and center variables were included in the analysis. During the study period, 2107 patients underwent liver transplant with DCD allografts. In most patients, DWIT and DAT were <30 minutes. DWIT was <30 minutes in 1804 donors, between 30 and 40 minutes in 248, and >40 minutes in 37. There was no difference in graft survival, duration of posttransplant hospital length of stay, and readmission rate between DCD liver transplants from donors with DWIT <30 minutes and DWIT between 30 and 40 minutes. Similar outcomes were noted for DAT. In the multivariate analysis, DAT and DWIT were not associated with graft loss. The predictors associated with graft loss were donor age, donor sharing, CIT, recipient admission to the intensive care unit, recipient ventilator dependence, Model for End-Stage Liver Disease score, and low-volume transplant centers. Any CIT cutoff >4 hours was associated with increased risk for graft loss. Longer CIT was also associated with a longer posttransplant hospital stay, higher rate of primary nonfunction, and hyperbilirubinemia. In conclusion, slightly longer DAT and DWIT (up to 40 minutes) were not associated with graft loss, longer posttransplant hospitalization, or hospital readmissions, whereas longer CIT was associated with worse outcomes after DCD liver transplants.

The UK-DCD-Risk-Score - practical and new guidance for allocation of a specific organ to a recipient?

Introduction: Multiple factors contribute to the overall outcome in donation after circulatory death liver transplantation. The majority is however inconsistently reported with various acceptance criteria and thresholds, when to decline a specific graft. Recent improvement in outcome was based on an increased awareness of the cumulative risk, combining donor and recipient parameters, which encouraged the community to accept livers with an overall higher risk. Areas covered: This review pictures the large number of risk factors in this field with a special focus on parameters, which contribute to available prediction models. Next, features of the recently developed UK-DCD-Risk-Score, which led to a significantly impaired graft survival, above a suggested threshold of >10 score points, are discussed. The clinical impact of this new model on the background of other prediction tools with their subsequent limitations is highlighted in a next chapter. Finally, we provide suggestions, how to further improve outcomes in this challenging field of transplantation. Expert opinion: Despite the recent development of new prediction models, including the UK-DCD-Risk-Score, which provides a sufficient prediction of graft loss after DCD liver transplantation, the consideration of other confounders is essential to better understand the overall risk and metabolic liver status to improve the comparability of clinical studies. More uniform definitions and thresholds of individual risk factors are required.

Expanding the Donor Pool With the Use of Extended Criteria Donation After Circulatory Death Livers

Use of donation after circulatory death (DCD) donor livers for transplantation has remained cautious in the United States. The aim of this study was to demonstrate the expansion of a DCD liver transplantation (LT) program with the use of extended criteria donor (ECD) DCD livers. After institutional review board approval, 135 consecutive DCD LTs were retrospectively studied. ECD DCD livers were defined as those with 1 of the following factors: donor age >50 years, donor body mass index >35 kg/m² , donor functional warm ischemia time >30 minutes, and donor liver macrosteatosis >30%. An optimization protocol was introduced in July 2011 to improve outcomes of DCD LT, which included thrombolytic donor flush and efforts to minimize ischemia times. The impact of this protocol on outcomes was evaluated in terms of graft loss, ischemic cholangiopathy (IC), and change in DCD LT volume. Of 135 consecutive DCD LTs, 62 were ECD DCDs. In total, 24 ECD DCD LTs were performed before (era 1) and 38 after the institution of optimization protocol (era 2), accounting for an increase in the use of ECD DCD livers from 39% to 52%. Overall outcomes of ECD DCD LT improved in era 2, with a significantly lower incidence of IC (5% versus 17% in era 1; P = 0.03) and better 1-year graft survival (93% versus 75% in era 1; P = 0.07). Survival outcomes for ECD DCD LT in era 2 were comparable to matched deceased donor LT. With the expansion of the DCD donor pool, the number of DCD LTs performed at our center gradually increased in era 2 to account for >20% of the center's LT volume. In conclusion, with the optimization of perioperative conditions, ECD DCD livers can be successfully transplanted to expand the donor pool for LT.