DCD lung donation: donor criteria, procedural criteria, pulmonary graft function validation, and preservation

Lung preservation: from perfusion to temperature

PURPOSE OF REVIEW

This article will review the evidence behind elements of the lung preservation process that have remained relatively stable over the past decade as well as summarize recent developments in ex-vivo lung perfusion and new research challenging the standard temperature for static cold storage.

RECENT FINDINGS

Ex-vivo lung perfusion is becoming an increasingly well established means to facilitate greater travel distance and allow for continued reassessment of marginal donor lungs. Preliminary reports of the use of normothermic regional perfusion to allow utilization of lungs after DCD recovery exist, but further research is needed to determine its ability to improve upon the current method of DCD lung recovery. Also, research from the University of Toronto is re-assessing the optimal temperature for static cold storage; pilot studies suggest it is a feasible means to allow for storage of lungs overnight to allow for daytime transplantation, but ongoing research is awaited to determine if outcomes are superior to traditional static cold storage.

SUMMARY

It is crucial to understand the fundamental principles of organ preservation to ensure optimal lung function posttransplant. Recent advances in the past several years have the potential to challenge standards of the past decade and reshape how lung transplantation is performed.

Primary graft dysfunction following lung transplantation: From pathogenesis to future frontiers

Lung transplantation is the treatment of choice for patients with end-stage lung disease. Currently, just under 5000 lung transplants are performed worldwide annually. However, a major scourge leading to 90-d and 1-year mortality remains primary graft dysfunction. It is a spectrum of lung injury ranging from mild to severe depending on the level of hypoxaemia and lung injury post-transplant. This review aims to provide an in-depth analysis of the epidemiology, pathophysiology, risk factors, outcomes, and future frontiers involved in mitigating primary graft dysfunction. The current diagnostic criteria are examined alongside changes from the previous definition. We also highlight the issues surrounding chronic lung allograft dysfunction and identify the novel therapies available for ex-vivo lung perfusion. Although primary graft dysfunction remains a significant contributor to 90-d and 1-year mortality, ongoing research and development abreast with current technological advancements have shed some light on the issue in pursuit of future diagnostic and therapeutic tools.

Short-term ex vivo tissue culture models help study human lung infectionsA review

Most studies on human lung infection have been performed using animal models, formalin or other fixed tissues, and in vitro cultures of established cell lines. However, the experimental data and results obtained from these studies may not completely represent the complicated molecular events that take place in intact human lung tissue in vivo. The newly developed ex vivo short-term tissue culture model can mimic the in vivo microenvironment of humans and allow investigations of different cell types that closely interact with each other in intact human lung tissues. Therefore, this kind of model may be a promising tool for future studies of different human lung infections, owing to its special advantages in providing more realistic events that occur in vivo. In this review, we have summarized the preliminary applications of this novel short-term ex vivo tissue culture model, with a particular emphasis on its applications in some common human lung infections.

Donation after circulatory death and lung transplantation

Lung transplantation is the most effective modality for the treatment of patients with end-stage lung diseases. Unfortunately, many people cannot benefit from this therapy due to insufficient donor availability. In this review and update article, we discuss donation after circulatory death (DCD), which is undoubtedly essential among the strategies developed to increase the donor pool. However, there are ethical and legislative considerations in the DCD process that are different from those of donation after brain death (DBD). Among others, the critical aspects of DCD are the concept of the end of life, cessation of futile treatments, and withdrawal of life-sustaining therapy. In addition, this review describes a rationale for using lungs from DCD donors and provides some important definitions, highlighting the key differences between DCD and DBD, including physiological aspects pertinent to each category. The unique ability of lungs to maintain cell viability without circulation, assuming that oxygen is supplied to the alveoli-an essential aspect of DCD-is also discussed. Furthermore, an updated review of the clinical experience with DCD for lung transplantation across international centers, recent advances in DCD, and some ethical dilemmas that deserve attention are also reported.

Trends in Donation After Circulatory Death in Lung Transplantation in the United States: Impact Of Era

Background: Use of lungs donated after circulatory death (DCD) has expanded, but changes in donor/recipient characteristics and comparison to brain dead donors (DBD) has not been studied. We examined the evolution of the use of DCD lungs for transplantation and compare outcomes to DBD lungs.

Methods: The SRTR database was used to construct three 5-year intervals. Perioperative variables and survival were compared by era and for DCD vs. DBD. Geographic variation was estimated using recipient permanent address.

Results: 728 DCD and 27,205 DBD lung transplants were identified. DCD volume increased from Era 1 (n = 73) to Era 3 (n = 528), representing 1.1% and 4.2% of lung transplants. Proportionally more DCD recipients were in ICU or on ECMO pre-transplant, and had shorter waitlist times. DCD donors were older, had lower PaO2/FiO2 ratios compared to DBD, more likely to be bilateral, had longer ischemic time, length of stay, post-op dialysis, and increased use of lung perfusion. There was no difference in overall survival. Geographically, use was heterogeneous.

Conclusion: DCD utilization is low but increasing. Despite increasing ischemic time and transplantation into sicker patients, survival is similar, which supports further DCD use in lung transplantation. DCD lung transplantation presents an opportunity to continue to expand the donor pool.

Rapid postmortem ventilation improves donor lung viability by extending the tolerable warm ischemic time after cardiac death in mice

Uncontrolled donation after cardiac death (uDCD) contributes little to ameliorating donor lung shortage due to rapidly progressive warm ischemia after circulatory arrest. Here, we demonstrated non-hypoxia improves donor lung viability in a novel uDCD lung transplant model undergoing rapid ventilation after cardiac death and compared the evolution of ischemia-reperfusion injury in mice that underwent pulmonary artery ligation (PAL). The tolerable warm ischemia time at 37ºC was initially determined in mice using a modified PAL model. The donor lung following PAL was also transplanted into syngeneic mice and compared to those that underwent rapid ventilation or no ventilation at 37ºC prior to transplantation. Twenty-four hours following reperfusion, lung histology, PaO2/FIO2 ratio, and inflammatory mediators were measured. Four hours of PAL had little impact on PaO2/FIO2 ratio and acute lung injury score in contrast to significant injury induced by 5 hours of PAL. Four-hour PAL lungs showed an early myeloid-dominant inflammatory signature when compared to naïve lungs and substantially injured five-hour PAL lungs. In the context of transplantation, unventilated donor lungs showed severe injury after reperfusion, whereas ventilated donor lungs showed minimal changes in PaO2/FIO2 ratio, histologic score, and expression of inflammatory markers. Taken together, the tolerable warm ischemia time of murine lungs at 37^oC can be extended by maintaining alveolar ventilation for up to 4 hours. Non-hypoxic lung warm ischemia-reperfusion injury shows an early transcriptional signature of myeloid cell recruitment and extracellular matrix proteolysis prior to blood-gas barrier dysfunction and significant tissue damage.

Current status and further potential of lung donation after circulatory death

Chronic organ shortage remains the most limiting factor in lung transplantation. To overcome this shortage, a minority of centers have started with efforts to reintroduce donation after circulatory death (DCD). This review aims to evaluate the experimental background, the current international clinical experience, and the further potential and challenges of the different DCD categories. Successful strategies have been implemented to reduce the problems of warm ischemic time, thrombosis after circulatory arrest, and difficulties in organ assessment, which come with DCD donation. From the currently reported results, controlled-DCD lungs are an effective and safe method with good mid-term and even long-term survival outcomes comparable to donation after brain death (DBD). Primary graft dysfunction and onset of chronic allograft dysfunction seem also comparable. Thus, controlled-DCD lungs should be ceased to be treated as marginal and instead be promoted as an equivalent alternative to DBD. A wide implementation of controlled-DCD-lung donation would significantly decrease the mortality on the waiting list. Therefore, further efforts in establishment of legislation and logistics are crucial. With regard to uncontrolled DCD, more data are needed analyzing long-term outcomes. To help with the detailed assessment and improvement of uncontrolled or otherwise questionable grafts after retrieval, ex-vivo lung perfusion is promising.

Unexpected cardio-circulatory arrest during a brain-dead donor organ retrieval

According to the Maastricht classification category of donation after circulatory death (DCD), type IV DCD refers to brain-dead donors who are re-categorized after unexpected circulatory arrest before donor organ retrieval. Clinical management is challenging, even in intensive care units, where most of this type of organ donation occurs. We report a case of the first successful lung transplantation (LTx) using type IV DCD organ in Taiwan. The recipient's recovery was satisfactory, without acute or chronic organ dysfunction. When unexpected events made the brain-dead donors suffer from sudden onset of cardiac arrest before or during organ donation surgery, immediately switching the retrieval protocol from donation after brain death (DBD) to DCD could expand the donor pool and increase organ supply. The well-prepared and experienced transplant team and prompt protocol switch made this transplant surgery possible.

Donation after circulatory death (DCD)-lung procurement

The number of lungs available for lung transplantation is far lower than the number of patients awaiting them. Consequently, there is a significant attrition rate while awaiting transplantation. Lung procurement rates are lower than those of other solid organs. Lungs are procured from only 15–20% of donors compared with 30% of decreased donors for hearts. The reason for this low retrieval rate is related to a number of factors. Brain death is associated with neurogenic pulmonary edema. Additionally, injury to the lung itself may occur before or after brain death. Aspiration of gastric contents, pneumonia, previous thoracic trauma, ventilator-associated injury, atelectasis, and pulmonary thrombosis/embolism may all contribute to lung injury before consideration for harvest. Donation after circulatory death (DCD) is one category of nontraditional organ donation now being performed in increasing numbers as a way to increase the number of lungs available for transplantation. In some studies, estimates show that utilization of DCD lung procurement could increase the number of lungs available by up to 50%.

Post-transplant outcomes of standard and extended criteria donation after circulatory death donor lungs categorized by donation after brain death lung criteria

 

OBJECTIVES

Most transplant centres use donation after brain death (DBD) criteria to assess the quality of controlled donation after circulatory death (cDCD) lungs. However, research on the relationship between DBD extended criteria and cDCD lung transplantation outcomes is limited. We investigated the outcomes of using DBD extended criteria donor organs in cDCD lung transplantation, compared to the standard criteria cDCD lung transplantation.

METHODS

A retrospective chart review of consecutive cDCD lung referrals to Hospital Universitario Puerta de Hierro-Majadahonda from June 2013 to December 2019 was undertaken. Donors were divided into standard and extended criteria groups. Early outcomes after lung transplant were compared between these groups using the Kaplan-Meier method and log-rank test.

RESULTS

Thirty out of 91 cDCD donor lung offers were accepted for transplantation, of which 11 were from standard criteria donors and 19 were extended criteria donors. The baseline characteristics of the 2 recipient groups were similar. There were no differences in the rates of grade 3 primary graft dysfunction at 72 h after lung transplantation (21% vs 18%), duration of mechanical ventilation (48 h vs 36 h), total intensive care unit stay (10 days vs 7 days) and 1-year survival (89% vs 90%).

CONCLUSIONS

Carefully selecting cDCD lungs from outside the standard acceptability criteria may expand the existing donor pool with no detrimental effects on lung transplantation outcomes.

Successful clinical transplantation of hearts donated after circulatory death using normothermic regional perfusion

BACKGROUND

Heart transplantation (HT) from donation after circulatory death (DCD) has yet to achieve wide clinical application despite the encouraging resultsreported recently. In this study we describe 2 cases of successful adult DCD HT performed at our institution using an original protocol.

METHODS

Our local abdominal DCD protocol was updated to allow DCD heart procurement, and was accepted by the institutional ethics committee. The main features of the protocol include: pre-mortem insertion of peripheral venoarterial extracorporeal membrane oxygenation cannulas; thoracoabdominal normothermic regional perfusion (NRP) by clamping the 3 aortic arch vessels to exclude cerebral circulation; and in-situ heart resuscitation. The retrieved hearts were directly transplanted into recipients located in an adjoining operating room.

RESULTS

The procurement warm ischemic time was 25 minutes for the first donor, and 26 minutes for the second donor. The cold ischemic time was 16 minutes for the first recipient and 17 minutes for the second recipient. The suture time was 30 minutes for the first recipient, and 53 minutes for the second recipient. Both recipients were easily weaned off cardiopulmonary bypass in sinus rhythm and inotropic support. Post-operative evaluation of cardiac function was excellent and the patients were subsequently discharged home.

CONCLUSIONS

Transplantation of hearts from DCD donors is now a clinical reality.NRP is a useful tool for resuscitation, reperfusion, and preservation of transplanted hearts. It also offers the opportunity to assess the function and viability of organs before transplantation. However,due to ethical issues, some may object to ante-mortem intervention.

Development of a Pulmonary Workshop for Organ Recovery Coordinators' Continuing Medical Education

Organ recovery coordinators (ORCs) have varied professional education backgrounds; however, based on their specialized education, their training may not have included in-depth mechanical ventilation and pulmonary management. An 8-hour pulmonary workshop was developed in collaboration between an organ procurement organization and a university-based respiratory care department. The workshop focused on pulmonary management and hands-on laboratory exercises using mechanical ventilators. A program assessment questionnaire was completed by participants following the workshop, which requested their self-reported comfort/familiarity with pulmonary management skills before and after the workshop on a 5-point Likert scale. Following the pulmonary workshop, the mean ORC comfort/familiarity for all pulmonary management skills increased significantly (P < .01). This program suggests ORCs can develop a greater awareness and comfort with pulmonary management by participating in a continuing education pulmonary workshop. Continuing education initiatives focused on pulmonary management of donor patients using hands-on competencies should be part of the ORCs practice improvement efforts.

Review 1: Lung transplant-from donor selection to graft preparation

For various end-stage lung diseases, lung transplantation remains one of the only viable treatment options. While the demand for lung transplantation has steadily risen over the last few decades, the availability of donor grafts is limited, which have resulted in progressively longer waiting lists. In the early years of lung transplantation, only the 'ideal' donor grafts are considered for transplantation. Due to the donor shortages, there is ongoing discussion about the safe use of 'suboptimal' grafts to expand the donor pool. In this review, we will discuss the considerations around donor selection, donor-recipient matching, graft preparation and graft optimisation.

Ex-vivo lung perfusion

PURPOSE OF REVIEW

Ex-vivo lung perfusion (EVLP) has been developed to expand the donor pool for lung transplantation recipients. The role of EVLP in organ preservation, evaluation and potential reconditioning is reviewed.

RECENT FINDINGS

EVLP has been shown to significantly increase the utilization of donor lungs for transplantation. Evidence suggests that patient outcomes from EVLP lungs are comparable to standard procurement technique. Novel strategies are being developed to treat and recondition injured donor lungs. EVLP may also prove to be a tool for translational research of lung diseases.

SUMMARY

EVLP has been shown to be an effective system to expand donor pool for lung transplantation without detriment to recipients. Future potential ex-vivo developments may further improve patient outcomes as well as increasing availability of donor organs.

Prevalence of Gout in the Surviving United States Solid Organ Transplantation Population

PURPOSE

Although incidence and survival are frequent topics within the solid organ transplantation (SOT) literature, the size of the surviving SOT population is not well known. Existing studies of gout in patients with SOT have focused on the incident SOT population. This analysis was performed to characterize the prevalent SOT population and the prevalence of gout within it.

METHODS

This study includes the 2017 United States (US) population size of recipients of kidney, heart, liver, and lung transplants that was estimated by combining primary transplant recipient cohort sizes (1988-2017) with previously published survival rates for each annual cohort's time since transplantation (0-29 years). Gout among prevalent patients with SOT was assessed using Medicare and commercial claims.

RESULTS

A total of 637,231 US patients received a primary kidney (393,953), liver (142,186), heart (66,637), or lung (34,455) transplant between 1988 and 2017. An estimated 356,000 (55.8%) recipients were alive in 2017 (233,000 kidney; 78,700 liver; 29,300 heart; 14,700 lung). Gout was identified in 11% of prevalent patients with SOT in 2016. Higher rates of gout were seen in recipients of kidney (13.1%) and heart (12.7%) compared to recipients of liver (6.7%) and lung (5.6%) (P < .0001 in both datasets). Active diagnosed gout prevalence in the US population without a SOT history was 1.1% in 2016.

CONCLUSIONS

Hundreds of thousands of US patients are living with a transplanted organ today and these numbers are likely to increase. In patients with SOT, gout is a frequent comorbidity of which physicians should be aware. This study suggests a markedly higher rate of gout among transplant recipients compared to the general US population.

Combined Thorax-Abdomen Extraction in Controlled Cardiac Death (Maastricht Type III) Donors

Donation after circulatory death (DCD) or controlled cardiac death (Maastricht type III donors) is that in which the irreversible cessation of circulatory and respiratory function occurs after the withdrawal of life-sustaining therapies. The shortage of available donor lungs has prompted the development of programs of controlled DCD for lung transplantation. The combined thorax-abdomen extraction in these cases is carried out only in a few centers in Spain, being even more exceptional considering the combined use of super rapid lung extraction with abdominal normothermic regional perfusion. The success achieved with the first cases of combined thorax-abdomen extraction in Maastricht type III donors in Navarra shows that it is a feasible and safe procedure.

Lung transplantation from donation after controlled cardiocirculatory death. Systematic review and meta-analysis

BACKGROUND

The interest in donation after cardiocirculatory death (DCD) donors for lung transplantation (LT) has been recently rekindled due to lung allograft shortage. Clinical outcomes following DCD have proved satisfactory. The aim of this systematic review is to provide a thorough analysis of published experience regarding outcomes of LT after controlled DCD compared with donation after brain death (DBD) donors.

METHODS

We performed a literature search in Cochrane Database of Systematic Reviews, PubMed and Web of Science using the items "lung transplantation" AND "donation after circulatory death" on November 1, 2018. The full text of relevant articles was evaluated by two authors independently. Quality assessment was performed using the NIH protocol for case-control and case series studies. A pooled Odds ratio (OR) and mean differences with inverse variance weighting using DerSimonian-Laird random effect models were computed to account for between-trial variance (τ2).

RESULTS

Of the 508 articles identified with our search, 9 regarding controlled donation after cardiac death (cDCD) were included in the systematic review, including 2973 patients (403 who received graft from DCD and 2570 who had DBD). Both 1-year survival and 2 and 3-grade primary graft dysfunction (PGD) were balanced between the two cohorts (OR = 1.00 and 1.03 respectively); OR for airway complications was 2.07 against cDCD. We also report an OR = 0.57 for chronic lung allograft dysfunction (CLAD) and an OR = 0.57 for 5-year survival against cDCD.

CONCLUSIONS

Our meta-analysis shows no significant difference between recipients after cDCD or DBD regarding 1-year survival, PGD and 1-year freedom from CLAD. Airway complications and long-term survival were both related with transplantation after cDCD, but these statistical associations need further research.

Criteria to Identify a Potential Deceased Organ Donor: A Systematic Review

OBJECTIVES

To systematically review the global published literature defining a potential deceased organ donor and identifying clinical triggers for deceased organ donation identification and referral.

DATA SOURCES

Medline and Embase databases from January 2006 to September 2017.

STUDY SELECTION

All published studies containing a definition of a potential deceased organ donor and/or clinical triggers for referring a potential deceased organ donor were eligible for inclusion. Dual, independent screening was conducted of 3,857 citations.

DATA EXTRACTION

Data extraction was completed by one team member and verified by a second team member. Thematic content analysis was used to identify clinical criteria for potential deceased organ donation identification from the published definitions and clinical triggers.

DATA SYNTHESIS

One hundred twenty-four articles were included in the review. Criteria fell into four categories: Neurological, Medical Decision, Cardiorespiratory, and Administrative. Distinct and globally consistent sets of clinical criteria by type of deceased organ donation (neurologic death determination, controlled donation after circulatory determination of death, and uncontrolled donation after circulatory determination of death) are reported.

CONCLUSIONS

Use of the clinical criteria sets reported will reduce ambiguity associated with the deceased organ donor identification and the subsequent referral process, potentially reducing the number of missed donors and saving lives globally through increased transplantation.

Prolonged warm ischemia exacerbated acute rejection after lung transplantation from donation after cardiac death in a mouse

OBJECTIVE

In lung transplantation (LTx) from donation after cardiac death (DCD), the donor lungs are inevitably exposed to warm ischemic time (WIT) between the cardiac arrest and the initiation of cold preservation. We conducted this study to examine the effect of prolonged WIT on lung allograft rejection in a murine model of LTx from DCD.

METHODS

Allogeneic BALB/c → B6 LTx from DCD was performed with a WIT of 15 min (WIT15 group, n = 5) or 60 min (WIT60 group, n = 5). Recipients were immunosuppressed by perioperative costimulatory blockade. The lung allografts were analyzed by histology and flow cytometry on day 7 after the LTx.

RESULTS

Histologically, the rejection grade in the WIT60 group was significantly higher than that in the WIT15 group (3.4 ± 0.4 vs. 2.2 ± 0.2, P = 0.0278). Moreover, the intragraft CD8+ to CD4+ T cell ratio in the WIT60 group was significantly higher than that in the WIT15 group (2.3 ± 0.12 vs. 1.2 ± 0.11, P < 0.0001).

CONCLUSIONS

Prolonged WIT could exacerbate the severity of lung allograft rejection after LTx from DCD. Minimization of the WIT could improve the outcomes after LTx from DCD.

Excellent long-term outcome with lungs obtained from uncontrolled donation after circulatory death

We aimed to propose a simple and effective preservation method in lungs procured for transplantation from uncontrolled donation after circulatory death (uDCD) associated with excellent long-term results. Outcome measures for lung recipients were survival and primary graft dysfunction (PGD) grade 3. Survival was estimated using the Kaplan-Meier method. A total of 9 lung uDCDs were evaluated and 8 lung transplants were performed. Mean no-flow time was 9.8 minutes (standard deviation [SD] 8.6). Mean time from cardiac arrest to topical cooling was 96.8 minutes (SD 16.8). Preservation time was 159 minutes (SD 31). Ex vivo lung perfusion was used to assess lung function prior to transplantation in 2 cases. Mean recipient age was 60.8 years (SD 3.1), and mean total ischemic time was 678 minutes (SD 132). PGD grade 3 was observed in 2 cases (25%). The 1-month, 1-year, and 5-year survival rates were 100%, 87.5%, and 87.5%, respectively. Mean follow-up was 52 months. The logistic complexity of procuring lungs from uDCDs for transplantation requires the development of new strategies designed to facilitate this type of donation. A program based on strict selection criteria, using a simple and effective preservation technique, may recover lung grafts with excellent long-term posttransplant outcomes.

Complement Therapeutics in the Multi-Organ Donor: Do or Don't?

Over the last decade, striking progress has been made in the field of organ transplantation, such as better surgical expertise and preservation techniques. Therefore, organ transplantation is nowadays considered a successful treatment in end-stage diseases of various organs, e.g. the kidney, liver, intestine, heart, and lungs. However, there are still barriers which prevent a lifelong survival of the donor graft in the recipient. Activation of the immune system is an important limiting factor in the transplantation process. As part of this pro-inflammatory environment, the complement system is triggered. Complement activation plays a key role in the transplantation process, as highlighted by the amount of studies in ischemia-reperfusion injury (IRI) and rejection. However, new insight have shown that complement is not only activated in the later stages of transplantation, but already commences in the donor. In deceased donors, complement activation is associated with deteriorated quality of deceased donor organs. Of importance, since most donor organs are derived from either brain-dead donors or deceased after circulatory death donors. The exact mechanisms and the role of the complement system in the pathophysiology of the deceased donor have been underexposed. This review provides an overview of the current knowledge on complement activation in the (multi-)organ donor. Targeting the complement system might be a promising therapeutic strategy to improve the quality of various donor organs. Therefore, we will discuss the complement therapeutics that already have been tested in the donor. Finally, we question whether complement therapeutics should be translated to the clinics and if all organs share the same potential complement targets, considering the physiological differences of each organ.

Extended criteria donor lung reconditioning with the organ care system lung: a single institution experience

Lung transplantation is a life-saving procedure limited by donor's availability. Lung reconditioning by ex vivo lung perfusion represents a tool to expand the donor pool. In this study, we describe our experience with the OCS™ Lung to assess and recondition extended criteria lungs. From January 2014 to October 2016, of 86 on-site donors evaluated, eight lungs have been identified as potentially treatable with OCS™ Lung. We analyzed data from these donors and the recipient outcomes after transplantation. All donor lungs improved during OCS perfusion in particular regarding the PaO₂ /FiO₂ ratio (from 340 mmHg in donor to 537 mmHg in OCS) leading to lung transplantation in all cases. Concerning postoperative results, primary graft dysfunction score 3 at 72 h was observed in one patient, while median mechanical ventilation time, ICU, and hospital stay were 60 h, 14 and 36 days respectively. One in-hospital death was recorded (12.5%), while other two patients died during follow-up leading to 1-year survival of 62.5%. The remaining five patients are alive and in good conditions. This case series demonstrates the feasibility and value of lung reconditioning with the OCS™ Lung; a prospective trial is underway to validate its role to safely increase the number of donor lungs.

Donation after circulatory death heart transplantation

PURPOSE OF REVIEW

Despite continued expansion in the use of extended-criteria donor hearts following donation after brain death, there remains an unacceptable discrepancy between the supply of suitable donor hearts and the demand from increasing recipient numbers on transplant wait lists. Until recently, the additional approach of utilizing organs following donation after circulatory death (DCD) had not been possible for clinical heart transplantation in the modern era. This review describes relevant advances in translational research and provides an update on the favourable adoption of this donation pathway for clinical heart transplantation.

RECENT FINDINGS

The use of an ex-situ transportable cardiac perfusion platform together with modified cardioplegia, supplemented with postconditioning agents, has allowed three centres to report successful transplantation of distantly procured human DCD hearts. This has been achieved by utilizing either a method of direct procurement and ex-situ perfusion on the device or through an initial in-situ reanimation with extracorporeal normothermic regional perfusion prior to ex-situ perfusion.

SUMMARY

DCD heart transplantation is feasible with excellent early outcomes. In the face of continued and significant donor organ shortage and inevitable wait list attrition, the rejection of suitable DCD hearts, in jurisdictions permitting this donation pathway, is increasingly difficult to justify.

Use of Lung Allografts From Donation After Cardiac Death Donors: A Single-Center Experience

BACKGROUND

Lung transplantation remains the only treatment for end-stage lung disease. Availability of suitable lungs does not parallel this growing trend. Centers using donation after cardiac death (DCD) donor lungs report comparable outcomes with those from brain-dead donors. Donor assessment protocols and consistent surgical teams have been advocated when considering using the use of DCD donors. We present our experience using lungs from Maastricht category III DCD donors.

METHODS

Starting 2007 to July 2016, 73 DCD donors were assessed, 44 provided suitable lungs that resulted in 46 transplants. A 2012 to October 2016 comparative cohort of 379 brain-dead donors were assessed. Recipient and donor characteristics and primary graft dysfunction (PGD) and survival were monitored.

RESULTS

Seventy-three DCD (40% dry run rate) donors assessed yielded 46 transplants (23 double, 6 right, and 17 left). Comparative cohort of 379 brain-dead donors yielded 237 transplants (112 double, 43 right, and 82 left). One- and 3-year recipient survival was 91% and 78% for recipients of DCD lungs and 91% and 75% for recipients of lungs from brain-dead donors, respectively. PGD 2 and 3 in DCD recipients at 72 hours was 4 of 46 (9%) and 6 of 46 (13%), respectively. Comparatively, brain-dead donor recipient cohort at 72 hours with PGD 2 and 3 was 23 of 237 (10%) and 41 of 237 (17%), respectively.

CONCLUSIONS

Our experience reaffirms the use of lungs from DCD donors as a viable source with favorable outcomes. Recipients from DCD donors showed equivalent PGD rate at 72 hours and survival compared with recipients from brain-dead donors.

In-hospital logistics: what are the key aspects for succeeding in each of the steps of the process of controlled donation after circulatory death?

Donation after circulatory death (DCD) donors are becoming an increasingly important population of organ donors in Europe and worldwide. We report the state of the art regarding controlled DCD donation describing the organizational and technical aspects of establishing a controlled DCD programme and provide recommendations regarding the introduction and development of this type of programme.

Steroids can reduce warm ischemic reperfusion injury in a porcine donation after circulatory death model with ex vivo lung perfusion evaluation

Donation after circulatory death (DCD) is being used to increase the number of transplantable organs. The role and timing of steroids in DCD donation and ex vivo lung perfusion (EVLP) has not been thoroughly investigated. In this study, we investigated the effect of steroids on warm ischemic injury in a porcine model (n = 6/group). Following cardiac arrest, grafts were left untouched in the donor (90-min warm ischemia). Graft function was assessed after 6 h of EVLP. In the MP group, 500 mg methylprednisolone was given prior to cardiac arrest and during EVLP. In the CONTR group, no steroids were added. Median lung compliance (13 ml/cmH₂ 0) was significantly better preserved in the CONTR group than in the MP group (30.5 ml/cmH₂ 0). Also, median wet-to-dry weight (6.11 vs. 6.94) and CT density (182.5 vs. 352.9 g/l) were significantly better in the MP group than in the CONTR group, respectively. There was no difference in oxygenation and pulmonary vascular resistance. Perfusate cytokine analysis showed a significant reduction in IL-1β, IL-8, IFN-α, IL-10, TNF-α, and IFN-γ in MP. Cytokines in bronchoalveolar lavage were not decreased except for IFN-gamma. We demonstrated that warm ischemic injury in DCD donation can be attenuated by steroids when given prior to warm ischemia and during EVLP. Ethical context of donor preconditioning should be discussed further.

Donors after cardiocirculatory death and lung transplantation

The number of patients actively awaiting lung transplantation (LTx) is more than the number of suitable donor lungs. The percentage of lung retrieval rate is lower when compared to other solid organs. The use of lungs from donation after cardiocirculatory death (DCD) donors is one of the options to avoid organ shortage in LTx. After extensive experimental research, clinical application of DCD donation is becoming wider. The results from most of the centers show at least equal survival rate compared to donors from brain death. This review paper will summarize experimental background and clinical experience from DCD donors.

Pyrrolidine dithiocarbamate administered during ex-vivo lung perfusion promotes rehabilitation of injured donor rat lungs obtained after prolonged warm ischemia

Damaged lung grafts obtained after circulatory death (DCD lungs) and warm ischemia may be at high risk of reperfusion injury after transplantation. Such lungs could be pharmacologically reconditioned using ex-vivo lung perfusion (EVLP). Since acute inflammation related to the activation of nuclear factor kappaB (NF-κB) is instrumental in lung reperfusion injury, we hypothesized that DCD lungs might be treated during EVLP by pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-κB. Rat lungs exposed to 1h warm ischemia and 2 h cold ischemia were subjected to EVLP during 4h, in absence (CTRL group, N = 6) or in presence of PDTC (2.5g/L, PDTC group, N = 6). Static pulmonary compliance (SPC), peak airway pressure (PAWP), pulmonary vascular resistance (PVR), and oxygenation capacity were determined during EVLP. After EVLP, we measured the weight gain of the heart-lung block (edema), and the concentration of LDH (cell damage), proteins (permeability edema) and of the cytokines IL-6, TNF-α and CINC-1 in bronchoalveolar lavage (BAL), and we evaluated NF-κB activation by the degree of phosphorylation and degradation of its inhibitor IκBα in lung tissue. In CTRL, we found significant NF-κB activation, lung edema, and a massive release of LDH, proteins and cytokines. SPC significantly decreased, PAWP and PVR increased, while oxygenation tended to decrease. Treatment with PDTC during EVLP inhibited NF-κB activation, did not influence LDH release, but markedly reduced lung edema and protein concentration in BAL, suppressed TNFα and IL-6 release, and abrogated the changes in SPC, PAWP and PVR, with unchanged oxygenation. In conclusion, suppression of innate immune activation during EVLP using the NF-κB inhibitor PDTC promotes significant improvement of damaged rat DCD lungs. Future studies will determine if such rehabilitated lungs are suitable for in vivo transplantation.