Clinical lung transplantation from uncontrolled non–heart-beating donors revisited

Outcomes after lung transplantation from selected donors older than 70 years in a single centre: time to close the debate?

OBJECTIVES

The aim of this study was to compare the outcomes of lung transplantations using grafts from donors aged over 70 years against those performed using younger donors.

METHODS

This retrospective single-centre analysis includes lung transplants conducted at our institution from January 2014 to June 2022. Lung recipients were classified into 2 groups based on donor age (group A <70 years; group B ≥70 years). Variables regarding demographics, peri and postoperative outcomes and survival were included. The statistical analysis approach included univariable analysis, propensity score matching to address imbalances in donor variables (smoking status), recipient characteristics (sex, age, diagnosis and lung allocation score) and calendar period and survival analysis.

RESULTS

A total of 353 lung transplants were performed in this period, 47 (13.3%) using grafts from donors aged over 70 years. Donors in group B were more frequently women (70.2% vs 51.6%, P = 0.017), with less smoking history (22% vs 43%, P = 0.002) and longer mechanical ventilation time (3 vs 2 days, P = 0.025). Recipients in group B had a higher lung allocation score (37.5 vs 35, P = 0.035). Postoperative variables were comparable between both groups, except for pulmonary function tests. Group B demonstrated lower forced expiratory volume 1 s levels (2070 vs 2580 ml, P = 0.001). The propensity score matching showed a lower chance of chronic lung allograft dysfunction by 12% for group B. One-, three- and five-year survival was equal between the groups.

CONCLUSIONS

The use of selected expanded-criteria donors aged over 70 years did not result in increased postoperative morbidity, early mortality or survival in this study.

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

Maximising organ utilisation from donation after circulatory death (DCD) donors could help meet some of the shortfall in organ supply, but it represents a major challenge, particularly as organ donors and transplant recipients become older and more medically complex over time. Success is dependent upon establishing common practices and accepted protocols that allow the safe sharing of DCD organs and maximise the use of the DCD donor pool. The British Transplantation Society 'Guideline on transplantation from deceased donors after circulatory death' has recently been updated. This manuscript summarises the relevant recommendations from chapters specifically related to transplantation of cardiothoracic organs.

Uncontrolled Donation after Circulatory Death Only Lung Program: An Urgent Opportunity

Uncontrolled donation after circulatory death (uDCD) represents a potential source of lungs, and since Steen's 2001 landmark case in Sweden, lungs have been recovered from uDCD donors and transplanted to patients in other European countries (France, the Netherlands, Spain and Italy) with promising results. Disparities still exist among European countries and among regions in Italy due to logistical and organizational factors. The present manuscript focuses on the clinical experiences pertaining to uDCD lungs in North America and European countries and on different lung maintenance methods. Existing experiences (and protocols) are not uniform, especially with respect to the type of lung maintenance, the definition of warm ischemic time (WIT) and, finally, the use of ex vivo perfusion (available in the last several years in most centers). In situ lung cooling may be superior to protective ventilation, but this process may be difficult to perform in the uDCD setting and is also time-consuming. On the other hand, the "protective ventilation technique" is simpler and feasible in every hospital. It may lead to a broader use of uDCD lung donors. To date, the results of lung transplants performed after protective ventilation as a preservation technique are scarce but promising. All the protocols comprise, among the inclusion criteria, a witnessed cardiac arrest. The detectable differences included preservation time (240 vs. 180 min) and donor age (<55 years in Spanish protocols and <65 years in Toronto protocols). Overall, independently of the differences in protocols, lungs from uDCD donors show promising results, and the possibility of optimizing ex vivo lung perfusion may broaden the use of these organs.

Organ Donation After Out-of-Hospital Cardiac Arrest: A Scientific Statement From the International Liaison Committee on Resuscitation

AIM OF THE REVIEW

Improving rates of organ donation among patients with out-of-hospital cardiac arrest who do not survive is an opportunity to save countless lives. The objectives of this scientific statement were to do the following: define the opportunity for organ donation among patients with out-of-hospital cardiac arrest; identify challenges and opportunities associated with organ donation by patients with cardiac arrest; identify strategies, including a generic protocol for organ donation after cardiac arrest, to increase the rate and consistency of organ donation from this population; and provide rationale for including organ donation as a key clinical outcome for all future cardiac arrest clinical trials and registries.

METHODS

The scope of this International Liaison Committee on Resuscitation scientific statement was approved by the International Liaison Committee on Resuscitation board and the American Heart Association, posted on ILCOR.org for public comment, and then assigned by section to primary and secondary authors. A unique literature search was completed and updated for each section.

RESULTS

There are a number of defining pathways for patients with out-of-hospital cardiac arrest to become organ donors; however, modifications in the Maastricht classification system need to be made to correctly identify these donors and to report outcomes with consistency. Suggested modifications to the minimum data set for reporting cardiac arrests will increase reporting of organ donation as an important resuscitation outcome. There are a number of challenges with implementing uncontrolled donation after cardiac death protocols, and the greatest impediment is the lack of legislation in most countries to mandate organ donation as the default option. Extracorporeal cardiopulmonary resuscitation has the potential to increase organ donation rates, but more research is needed to derive neuroprognostication rules to guide clinical decision-making about when to stop extracorporeal cardiopulmonary resuscitation and to evaluate cost-effectiveness.

CONCLUSIONS

All health systems should develop, implement, and evaluate protocols designed to optimize organ donation opportunities for patients who have an out-of-hospital cardiac arrest and failed attempts at resuscitation.

Organ Donation After Out-of-Hospital Cardiac Arrest: A Scientific Statement From the International Liaison Committee on Resuscitation

AIM OF THE REVIEW

Improving rates of organ donation among patients with out-of-hospital cardiac arrest who do not survive is an opportunity to save countless lives. The objectives of this scientific statement were to do the following: define the opportunity for organ donation among patients with out-of-hospital cardiac arrest; identify challenges and opportunities associated with organ donation by patients with cardiac arrest; identify strategies, including a generic protocol for organ donation after cardiac arrest, to increase the rate and consistency of organ donation from this population; and provide rationale for including organ donation as a key clinical outcome for all future cardiac arrest clinical trials and registries.

METHODS

The scope of this International Liaison Committee on Resuscitation scientific statement was approved by the International Liaison Committee on Resuscitation board and the American Heart Association, posted on ILCOR.org for public comment, and then assigned by section to primary and secondary authors. A unique literature search was completed and updated for each section.

RESULTS

There are a number of defining pathways for patients with out-of-hospital cardiac arrest to become organ donors; however, modifications in the Maastricht classification system need to be made to correctly identify these donors and to report outcomes with consistency. Suggested modifications to the minimum data set for reporting cardiac arrests will increase reporting of organ donation as an important resuscitation outcome. There are a number of challenges with implementing uncontrolled donation after cardiac death protocols, and the greatest impediment is the lack of legislation in most countries to mandate organ donation as the default option. Extracorporeal cardiopulmonary resuscitation has the potential to increase organ donation rates, but more research is needed to derive neuroprognostication rules to guide clinical decision-making about when to stop extracorporeal cardiopulmonary resuscitation and to evaluate cost-effectiveness.

CONCLUSIONS

All health systems should develop, implement, and evaluate protocols designed to optimise organ donation opportunities for patients who have an out-of-hospital cardiac arrest and failed attempts at resuscitation.

Expanding Donor Options for Lung Transplant: Extended Criteria, Donation After Circulatory Death, ABO Incompatibility, and Evolution of Ex Vivo Lung Perfusion

Only using brain-dead donors with standard criteria, the existing donor shortage has never improved in lung transplantation. Currently, clinical efforts have sought the means to use cohorts of untapped donors, such as extended criteria donors, donation after circulatory death, and donors that are ABO blood group incompatible, and establish the evidence for their potential contribution to the lung transplant needs. Also, technical maturation for using those lungs may eliminate immediate concerns about the early posttransplant course, such as primary graft dysfunction or hyperacute rejection. In addition, recent clinical and preclinical advances in ex vivo lung perfusion techniques have allowed the safer use of lungs from high-risk donors and graft modification to match grafts to recipients and may improve posttransplant outcomes. This review summarizes recent trends and accomplishments and future applications for expanding the donor pool in lung transplantation.

Donation After Circulatory Death in lung transplantation

The continuing shortage of pulmonary grafts from donors after brain death has led to a resurgence of interest in lung transplantation from donors after circulatory death (DCD). Most lungs from donors after withdrawal from life-sustaining therapy can be recovered rapidly and transplanted directly without ex-vivo assessment in case functional warm ischemic time is limited to 30 to 60 min. The potential of the DCD lung pool is still underutilized and should be maximized in countries with existing legislation. Countries lacking a DCD pathway should be encouraged to develop national ethical, professional, and legal frameworks to address public and professional concerns.

Mesenchymal Stromal/Stem Cells and Their Products as a Therapeutic Tool to Advance Lung Transplantation

Lung transplantation (LTx) has become the gold standard treatment for end-stage respiratory failure. Recently, extended lung donor criteria have been applied to decrease the mortality rate of patients on the waiting list. Moreover, ex vivo lung perfusion (EVLP) has been used to improve the number/quality of previously unacceptable lungs. Despite the above-mentioned progress, the morbidity/mortality of LTx remains high compared to other solid organ transplants. Lungs are particularly susceptible to ischemia-reperfusion injury, which can lead to graft dysfunction. Therefore, the success of LTx is related to the quality/function of the graft, and EVLP represents an opportunity to protect/regenerate the lungs before transplantation. Increasing evidence supports the use of mesenchymal stromal/stem cells (MSCs) as a therapeutic strategy to improve EVLP. The therapeutic properties of MSC are partially mediated by secreted factors. Hence, the strategy of lung perfusion with MSCs and/or their products pave the way for a new innovative approach that further increases the potential for the use of EVLP. This article provides an overview of experimental, preclinical and clinical studies supporting the application of MSCs to improve EVLP, the ultimate goal being efficient organ reconditioning in order to expand the donor lung pool and to improve transplant outcomes.

Donation after circulatory death donors in lung transplantation

Transplantation of any organ into a recipient requires a donor. Lung transplant has a long history of an inadequate number of suitable donors to meet demand, leading to deaths on the waiting list annually since national data was collected, and strict listing criteria. Before the Uniform Determination of Death Act (UDDA), passed in 1980, legally defined brain death in the U.S., all donors for lung transplant came from sudden death victims [uncontrolled Donation after Circulatory Death donors (uDCDs)] in the recipient’s hospital emergency department. After passage of the UDDA, uDCDs were abandoned to Donation after Brain Death donors (DBDs)—perhaps prematurely. Compared to livers and kidneys, many DBDs have lungs that are unsuitable for transplant, due to aspiration pneumonia, neurogenic pulmonary edema, trauma, and the effects of brain death on lung function. Another group of donors has become available—patients with a devastating irrecoverable brain injury that do not meet criteria for brain death. If a decision is made by next-of-kin (NOK) to withdraw life support and allow death to occur by asphyxiation, with NOK consent, these individuals can have organs recovered if death occurs relatively quickly after cessation of mechanical ventilation and maintenance of their airway. These are known as controlled Donation after Circulatory Death donors (cDCDs). For a variety of reasons, in the U.S., lungs are recovered from cDCDs at a much lower rate than kidneys and livers. Ex-vivo lung perfusion (EVLP) in the last decade has had a modest impact on increasing the number of lungs for transplant from DBDs, but may have had a larger impact on lungs from cDCDs, and may be indispensable for safe transplantation of lungs from uDCDs. In the next decade, DCDs may have a substantial impact on the number of lung transplants performed in the U.S. and around the world.

Role of normothermic perfusion with ECMO in donation after controlled cardiac death in Spain

Spain has become one of the most active countries in donation after controlled cardiac death, using normothermic abdominal perfusion with ECMO in more than 50% of all donors - a situation contributed to by the creation of mobile teams to support hospitals lacking this technology. The donation process must be respectful of the wishes and values of the patients and their relatives, especially if there is pre mortem manipulation, and the absence of cerebral perfusion should be guaranteed. The liver is the most benefited organ by reducing biliary complications as well as the loss of grafts. In renal transplantation, the technique could contribute to reduce the incidence of delayed graft function. In addition, the procedure is compatible with surgical rapid recovery in hypothermia when there is also lung donation. The future lies in the consolidation of cardiac donation by extending normothermic perfusion to the thoracic cavity.

Lung transplantation from uncontrolled and controlled donation after circulatory death: similar outcomes to brain death donors

Controlled donation after circulatory death donors (cDCD) are becoming a frequent source of lungs grafts worldwide. Conversely, lung transplantations (LTx) from uncontrolled donors (uDCD) are sporadically reported. We aimed to review our institutional experience using both uDCD and cDCD and compare to LTx from brain death donors (DBD). This is a retrospective analysis of all LTx performed between January 2013 and December 2019 in our institution. Donor and recipient characteristics were collected and univariate, multivariate and survival analyses were carried out comparing the three cohorts of donors. A total of 239 (84.7%) LTx were performed from DBD, 29 (10.3%) from cDCD and 14 (5%) from uDCD. There were no statistically significant differences in primary graft dysfunction grade 3 at 72 h, 30- and 90-day mortality, need for extracorporeal membrane oxygenation after procedure, ICU and hospital length of stay, airway complications, CLAD incidence or survival at 1 and 3 years after transplant (DBD: 87.1% and 78.1%; cDCD: 89.7% and 89.7%; uDCD: 85.7% and 85.7% respectively; P = 0.42). Short- and mid-term outcomes are comparable between the three types of donors. These findings may encourage and reinforce all types of donation after circulatory death programmes as a valid and growing source of suitable organs for transplantation.

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%.

Extended-criteria uncontrolled DCD donor for a fragile recipient: A case report about a challenging yet successful lung transplantation

INTRODUCTION

Lung donation after circulatory death (DCD) has proved to be an effective strategy for expanding the donor pool, but is still considered challenging. We report a successful case of lung procurement from an extended-criteria uncontrolled DCD.

PRESENTATION OF CASE

We evaluated the lungs of an uncontrolled DCD from a hospital without extracorporeal membrane oxygenation (ECMO) program. The donor was a non-smoker 20-year old male with a history of cardiomyopathy, cardiocirculatory arrests, and Lennox-Gastaut syndrome. Cardiac arrest occurred in a swimming pool, and bronchoscopy showed signs of inhalation. We employed our usual normothermic in-situ open-ventilated lung approach. After retrieval, lungs were stored on ice, then evaluated with ex-vivo lung perfusion (EVLP) and judged suitable for transplantation. The recipient was a 26-year old female with cystic fibrosis on long-term oxygen therapy, on the waitlist for up to 21 months due to her anthropomorphic characteristics. She required central VA-ECMO support during bilateral lung transplantation. Primary graft dysfunction (PGD) within the first 72 h reached grade 3; post-operative peripheral VV-ECMO support was discontinued two days after surgery. The patient was discharged 28 days after surgery; she is alive two years after transplantation with no signs of rejection nor anastomotic complications.

DISCUSSION

Despite the spreading use of lungs from controlled DCD, perplexities remain on uncontrolled DCD, namely: severe PDG, postoperative mortality, airway complications.

CONCLUSION

Our case report suggests that good results can be achieved with uncontrolled DCD despite the presence of relative contraindications: inhalation of water, prolonged ischemic times and recipient in poor conditions.

Uncontrolled Donation After Circulatory Death: A Unique Opportunity

Uncontrolled donation after circulatory death (uDCD) refers to donation from persons who die following an unexpected and unsuccessfully resuscitated cardiac arrest. Despite the large potential for uDCD, programs of this kind only exist in a reduced number of countries with a limited activity. Barriers to uDCD are of a logistical and ethical-legal nature, as well as arising from the lack of confidence in the results of transplants from uDCD donors. The procedure needs to be designed to reduce and limit the impact of the prolonged warm ischemia inherent to the uDCD process, and to deal with the ethical issues that this practice poses: termination of advanced cardiopulmonary resuscitation, extension of advanced cardiopulmonary resuscitation beyond futility for organ preservation, moment to approach families to discuss donation opportunities, criteria for the determination of death, or the use of normothermic regional perfusion for the in situ preservation of organs. Although the incidence of primary nonfunction and delayed graft function is higher with organs obtained from uDCD donors, overall patient and graft survival is acceptable in kidney, liver, and lung transplantation, with a proper selection and management of both donors and recipients. Normothermic regional perfusion has shown to be critical to achieve optimal outcomes in uDCD kidney and liver transplantation. However, the role of ex situ preservation with machine perfusion is still to be elucidated. uDCD is a unique opportunity to improve patient access to transplantation therapies and to offer more patients the chance to donate organs after death, if this is consistent with their wishes and values.

Developments in lung transplantation over the past decade

With an improved median survival of 6.2 years, lung transplantation has become an increasingly acceptable treatment option for end-stage lung disease. Besides survival benefit, improvement of quality of life is achieved in the vast majority of patients. Many developments have taken place in the field of lung transplantation over the past decade. Broadened indication criteria and bridging techniques for patients awaiting lung transplantation have led to increased waiting lists and changes in allocation schemes worldwide. Moreover, the use of previously unacceptable donor lungs for lung transplantation has increased, with donations from donors after cardiac death, donors with increasing age and donors with positive smoking status extending the donor pool substantially. Use of ex vivo lung perfusion further increased the number of lungs suitable for lung transplantation. Nonetheless, the use of these previously unacceptable lungs did not have detrimental effects on survival and long-term graft outcomes, and has decreased waiting list mortality. To further improve long-term outcomes, strategies have been proposed to modify chronic lung allograft dysfunction progression and minimise toxic immunosuppressive effects. This review summarises the developments in clinical lung transplantation over the past decade.

Many developments have taken place in lung transplantation over the last decade: indications have broadened, donor criteria expanded, allocations systems changed, and novel therapeutic interventions implemented, leading to improved long-term survivalhttp://bit.ly/2vnpwc1

Role of normothermic perfusión with ECMO in donation after controlled cardiac death in Spain

Spain has become one of the most active countries in donation after controlled cardiac death, using normothermic abdominal perfusion with ECMO in more than 50% of all donors - a situation contributed to by the creation of mobile teams to support hospitals lacking this technology. The donation process must be respectful of the wishes and values of the patients and their relatives, especially if there is pre mortem manipulation, and the absence of cerebral perfusion should be guaranteed. The liver is the most benefited organ by reducing biliary complications as well as the loss of grafts. In renal transplantation, the technique could contribute to reduce the incidence of delayed graft function. In addition, the procedure is compatible with surgical rapid recovery in hypothermia when there is also lung donation. The future lies in the consolidation of cardiac donation by extending normothermic perfusion to the thoracic cavity.

Initial lung transplantation experience with uncontrolled donation after cardiac death in North America

Uncontrolled donation after cardiac death (uDCD) has the potential to ameliorate the shortage of suitable lungs for transplant. To date, no lung transplant data from these donors are available from North America. We describe the successful use of these donors using a simple method of in situ lung inflation so that the organ can be protected from warm ischemic injury. Forty-four potential donors were approached, and family consent was obtained in 30 cases (68%). Of these, the lung transplant team evaluated 16 uDCDs on site, and 14 were considered for transplant pending ex vivo lung perfusion assessment. Five lungs were ultimately used for transplant (16.7% use rate from consented donors). The mean warm ischemic time was 2.8 hours. No primary graft dysfunction grade 3 was observed at 24, 48, or 72 hours after transplant. Median intensive care unit stay was 5 days (range: 2-78 days), and median hospital stay was 17 days (range: 8-100 days). The 30-day mortality was 0%. Four of 5 patients are alive at a median of 651 days (range: 121-1254 days) with preserved lung function. This study demonstrates the proof of concept and the potential for uDCD lung donation using a simple donor intervention.

Successful preservation and transplant of warm ischaemic lungs from controlled donors after circulatory death by prolonged in situ ventilation during normothermic regional perfusion of abdominal organs

OBJECTIVES

Donation after circulatory death (DCD) potentially provides transplantable lungs suitable for a transplant, but in Italy, the need for 20 min of a no-touch period after cardiac arrest for legal declaration of death poses real challenges to organ preservation.

METHODS

This is a single-institution, retrospective study using data collected prospectively between October and December 2017. After the approval of the multidisciplinary DCD study group of Regione Lombardia, Maastricht category III DCD donors became eligible for combined procurement of lungs and abdominal organs. Our group subsequently established a dedicated technical protocol. Our protocol consists of a non-rapid normothermic open-lung procurement process that takes place during abdominal normothermic regional perfusion, namely without pleural topical cooling before the start of pneumoplegia. After the lung is procured according to the technique described in the article, lung function is evaluated by ex vivo lung perfusion, which is run with the low-flow, open atrium, low haematocrit technique.

RESULTS

During the study, we managed 5 controlled DCDs. In 3 cases, the lungs were successfully transplanted. All 3 patients are alive after 1 year, with good respiratory function.

CONCLUSIONS

Our approach resulted in adequate lung preservation and successful transplants without detrimental effects on abdominal organ procurement, confirming the possibility of overcoming the obstacle of a long no-touch period in a DCD setting.

Mitigation of Primary Graft Dysfunction in Lung Transplantation: Current Understanding and Hopes for the Future

Primary graft dysfunction (PGD) is a form of acute lung injury that develops within the first 72 hours after lung transplantation. The overall incidence of PGD is estimated to be around 30%, and the 30-day mortality for grade 3 PGD around 36%. PGD is also associated with the development of bronchiolitis obliterans syndrome, a specific form of chronic lung allograft dysfunction. In this article, we will discuss perioperative strategies for PGD prevention as well as possible future avenues for prevention and treatment.

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.

Donation after circulatory death and its expansion in Spain

PURPOSE OF REVIEW

Donation after circulatory death (DCD) is still performed in a limited number of countries. This article summarizes the development of DCD in Spain and presents recent Spanish contributions to gain knowledge on the potential benefits and the practical use of normothermic regional perfusion (nRP).

RECENT FINDINGS

DCD now contributes to 24% of deceased donors in Spain. The development of DCD has been based on an assessment of practices in the treatment of cardiac arrest and end-of-life care to accommodate the option of DCD; the creation of an adequate regulatory framework; and institutional support, professional training and public education. Appropriate posttransplant outcomes have been obtained with organs from both uncontrolled and controlled DCD donors. nRP is increasingly used, with preliminary data supporting improved results compared with other in-situ preservation/recovery approaches. Mobile teams with portable extracorporeal membrane oxygenation devices are making nRP possible in hospitals without these resources. To avoid the possibility of reestablishing brain circulation after the determination of death, a specific methodology has been validated.

SUMMARY

DCD has been successfully developed in Spain following a streamlined process. nRP may become a standard in DCD, although further evidence on the benefits of this technology is eagerly awaited.

The Future of Lung Transplantation

The field of lung transplant has made significant advances over the last several decades. Despite these advances, morbidity and mortality remain high when compared with other solid organ transplants. As the field moves forward, the speed by which progress can be made will in part be determined by our ability to overcome several stumbling blocks, including donor shortage, proper selection of candidates, primary graft dysfunction, and chronic lung allograft dysfunction. The advances and developments surrounding these factors will have a significant impact on shaping the field within the coming years. In this review, we look at the current climate (ripe for expanding the donor pool), new technology (ex vivo lung perfusion and bioengineered lungs), cutting-edge innovation (novel biomarkers and new ways to treat infected donors), and evidence-based medicine to discuss current trends and predict future developments for what we hope is a bright future for the field of lung transplantation.

Historical perspectives of lung transplantation: connecting the dots

Lung transplantation is now a treatment option for many patients with end-stage lung disease. Now 55 years since the first human lung transplant, this is a good time to reflect upon the history of lung transplantation, to recognize major milestones in the field, and to learn from others' unsuccessful transplant experiences. James Hardy was instrumental in developing experimental thoracic transplantation, performing the first human lung transplant in 1963. George Magovern and Adolph Yates carried out the second human lung transplant a few days later. With a combined survival of only 26 days for these first 2 lung transplant recipients, the specialty of lung transplantation clearly had a long way to go. The first "successful" lung transplant, in which the recipient survived for 10.5 months, was reported by Fritz Derom in 1971. Ten years later, Bruce Reitz and colleagues performed the first successful en bloc transplantation of the heart and one lung with a single distal tracheal anastomosis. In 1988, Alexander Patterson performed the first successful double lung transplant. The modern technique of sequential double lung transplantation and anastomosis performed at the mainstem bronchus level was originally described by Henri Metras in 1950, but was not reintroduced into the field until Pasque reported it again in 1990. Since then, lung transplantation has seen landmark changes: evolving immunosuppression regimens, clarifying the definition of primary graft dysfunction (PGD), establishing the lung allocation score (LAS), introducing extracorporeal membrane oxygenation (ECMO) as a bridge to transplant, allowing donation after cardiac death, and implementing ex vivo perfusion, to name a few. This article attempts to connect the historical dots in this field of research, with the hope that our effort helps summarize what has been achieved, and identifies opportunities for future generations of transplant pulmonologists and surgeons alike.

Machine perfusion of thoracic organs

This article summarizes recent knowledge and clinical advances in machine perfusion (MP) of thoracic organs. MP of thoracic organs has gained much attention during the last decade. Clinical studies are investigating the role of MP to preserve, resuscitate, and assess heart and lungs prior to transplantation. Currently, MP of the cardiac allograft is essential in all type DCD heart transplantation while MP of the pulmonary allograft is mandatory in uncontrolled DCD lung transplantation. MP of thoracic organs also offers an exciting platform to further investigate downregulation of the innate and adaptive immunity prior to reperfusion of the allograft in recipients. MP provides a promising technology that allows pre-transplant preservation, resuscitation, assessment, repair, and conditioning of cardiac and pulmonary allografts outside the body in a near physiologic state prior to planned transplantation. Results of ongoing clinical trials are awaited to estimate the true clinical value of this new technology in advancing the field of heart and lung transplantation by increasing the total number and the quality of available organs and by further improving recipient early and long-term outcome.

Expanding the donor lung pool: how many donations after circulatory death organs are we missing?

BACKGROUND

The number of patients with end-stage pulmonary disease awaiting lung transplantation is at an all-time high, while the supply of available organs remains stagnant. Utilizing donation after circulatory death (DCD) donors may help to address the supply-demand mismatch. The objective of this study is to determine the potential donor pool expansion with increased procurement of DCD organs from patients who die at hospitals.

MATERIAL AND METHODS

The charts of all patients who died at a single, rural, quaternary-care institution between August 2014 and June 2015 were reviewed for lung transplant candidacy. Inclusion criteria were age <65 y, absence of cancer and lung pathology, and cause of death other than respiratory or sepsis.

RESULTS

A total of 857 patients died within a 1-year period and were stratified by age: pediatric <15 y (n = 32, 4%), young 15-64 y (n = 328, 38%), and old >65 y (n = 497, 58%). Those without cancer totaled 778 (90.8%) and 512 (59%) did not have lung pathology. This leaves 85 patients qualifying for DCD lung donation (pediatric n = 10, young n = 75, and old n = 0). Potential donors were significantly more likely to have clear chest X-rays (24.3% versus 10.0%, P < 0.0001) and higher mean PaO2/FiO2 (342.1 versus 197.9, P < 0.0001) compared with ineligible patients.

CONCLUSIONS

A significant number of DCD lungs are available every year from patients who die within hospitals. We estimate the use of suitable DCD lungs could potentially result in a significant increase in the number of lungs available for transplantation.

Stereological assessment of the blood-air barrier and the surfactant system after mesenchymal stem cell pretreatment in a porcine non-heart-beating donor model for lung transplantation

More frequent utilization of non-heart-beating donor (NHBD) organs for lung transplantation has the potential to relieve the shortage of donor organs. In particular with respect to uncontrolled NHBD, concerns exist regarding the risk of ischaemia/reperfusion (IR) injury-related graft damage or dysfunction. Due to their immunomodulating and tissue-remodelling properties, bone-marrow-derived mesenchymal stem cells (MSCs) have been suspected of playing a beneficial role regarding short- and long-term survival and function of the allograft. Thus, MSC administration might represent a promising pretreatment strategy for NHBD organs. To study the initial effects of warm ischaemia and MSC application, a large animal lung transplantation model was generated, and the structural organ composition of the transplanted lungs was analysed stereologically with particular respect to the blood-gas barrier and the surfactant system. In this study, porcine lungs (n = 5/group) were analysed. Group 1 was the sham-operated control group. In pigs of groups 2-4, cardiac arrest was induced, followed by a period of 3 h of ventilated ischaemia at room temperature. In groups 3 and 4, 50 × 10⁶ MSCs were administered intravascularly via the pulmonary artery and endobronchially, respectively, during the last 10 min of ischaemia. The left lungs were transplanted, followed by a reperfusion period of 4 h. Then, lungs were perfusion-fixed and processed for light and electron microscopy. Samples were analysed stereologically for IR injury-related structural parameters, including volume densities and absolute volumes of parenchyma components, alveolar septum components, intra-alveolar oedema, and the intracellular and intra-alveolar surfactant pool. Additionally, the volume-weighted mean volume of lamellar bodies (lbs) and their profile size distribution were determined. Three hours of ventilated warm ischaemia was tolerated without eliciting histological or ultrastructural signs of IR injury, as revealed by qualitative and quantitative assessment. However, warm ischaemia influenced the surfactant system. The volume-weighted mean volume of lbs was reduced significantly (P = 0.024) in groups subjected to ischaemia (group medians of groups 2-4: 0.180-0.373 μm³) compared with the sham control group (median 0.814 μm³). This was due to a lower number of large lb profiles (size classes 5-15). In contrast, the intra-alveolar surfactant system was not altered significantly. No significant differences were encountered comparing ischaemia alone (group 2) or ischaemia plus application of MSCs (groups 3 and 4) in this short-term model.

History of lung transplantation

Lung transplantation nowadays is a well-accepted and routine treatment for well selected patients with terminal respiratory disease. However, it took several decades of experimental studies and clinical attempts to reach this success. In this paper, we describe the early experimental activity from the mid-forties until the early sixties. The first clinical attempt in humans was reported by Hardy and Webb in 1963 followed by others with short survival only except for one case by Derom et al. who lived for 10 months. Long-term successes were not reported until after the discovery of cyclosporine as a new immunosuppressive agent. Successful heart-lung transplantation (HLTx) for pulmonary vascular disease was performed by the Stanford group starting in 1981 while the Toronto group described good outcome after single-lung transplantation (SLTx) for pulmonary fibrosis in 1983 and after double-lung transplantation for emphysema in 1986. Further evolution in surgical techniques and in transplant type for the various forms of end-stage lung diseases are reviewed. The evolution in lung transplantation still continues nowadays with the use of pulmonary allografts coming from living-related donors, from donors after circulatory death, or after prior assessment and reconditioning during ex vivo lung perfusion (EVLP) in an attempt to overcome the critical shortage of suitable organs. Early outcome has significantly improved over the last three decades. Better treatment and prevention of chronic lung allograft dysfunction will hopefully result in further improvement of long-term survival after lung transplantation.

Principi e indicazioni dell’assistenza circolatoria e respiratoria extracorporea in chirurgia toracica

In origine, l’extracorporeal membrane oxygenation (ECMO) era una tecnica di assistenza respiratoria che utilizzava uno scambiatore gassoso a membrana. Per estensione, l’ECMO è diventata una tecnica respiratoria e cardiopolmonare utilizzata in caso di deficit respiratorio e/o cardiaco nell’attesa della restaurazione della funzione deficitaria o di un eventuale trapianto. Il supporto emodinamico può essere parziale o totale. Gli accessi vascolari possono essere periferici o centrali. Questo tipo di assistenza utilizza il concetto di circolazione extracorporea (CEC) sanguigna che in epoca moderna si è estesa con l’utilizzo di polmoni artificiali a membrana. Il circuito di base è semplice e comprende una pompa, un ossigenatore (che permette al sangue di caricarsi di O₂ e di eliminare CO₂) e delle vie d’accesso (una di drenaggio e una di reinfusione). La sua attuazione è facile, veloce e può essere avviata al letto del malato. Il miglioramento delle attrezzature, una migliore conoscenza delle tecniche e delle indicazioni, e le politiche di salute pubblica hanno reso popolare questa tecnica. Alcuni centri di chirurgia toracica la utilizzano di routine come assistenza alla realizzazione di un intervento terapeutico (soprattutto trapianto) assieme a team di rianimazione per il trattamento della sindrome da distress respiratorio acuto. Nel quadro della malattia polmonare dell’adulto, l’idea principale è quella di sviluppare il concetto di strategia minimalista con l’uso di una CEC adiuvante parziale – più che sostitutiva totale – che permetterebbe il recupero metabolico ad integrum del paziente. Nei prossimi anni, i progressi della tecnologia e dell’ingegneria così come le conoscenze approfondite permetteranno il miglioramento della prognosi dei pazienti colpiti da deficit respiratorio sotto assistenza meccanica.

Beware Cold Agglutinins in Organ Donors! Ex Vivo Lung Perfusion From an Uncontrolled Donation After Circulatory-Determination-of-Death Donor With a Cold Agglutinin: A Case Report

BACKGROUND

We began to recover lungs from uncontrolled donation after circulatory determination of death to assess for transplant suitability by means of ex vivo lung perfusion (EVLP) and computerized tomographic (CT) scan. Our first case had a cold agglutinin with an interesting outcome.

CASE REPORT

A 60-year-old man collapsed at home and was pronounced dead by Emergency Medical Services personnel. Next-of-kin consented to lung retrieval, and the decedent was ventilated and transported. Lungs were flushed with cold Perfadex, removed, and stored cold. The lungs did not flush well. Medical history revealed a recent hemolytic anemia and a known cold agglutinin. Warm nonventilated ischemia time was 51 minutes. O2-ventilated ischemia time was 141 minutes. Total cold ischemia time was 6.5 hours. At cannulation for EVLP, established clots were retrieved from both pulmonary arteries. At initiation of EVLP with Steen solution, tiny red aggregates were observed initially. With warming, the aggregates disappeared and the perfusate became red. After 1 hour, EVLP was stopped because of florid pulmonary edema. The lungs were cooled to 20°C; tiny red aggregates formed again in the perfusate. Ex vivo CT scan showed areas of pulmonary edema and a pyramidal right middle lobe opacity. Dissection showed multiple pulmonary emboli-the likely cause of death. However, histology showed agglutinated red blood cells in the microvasculature in pre- and post-EVLP biopsies, which may have contributed to inadequate parenchymal preservation.

CONCLUSIONS

Organ donors with cold agglutinins may not be suitable owing to the impact of hypothermic preservation.

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.

Pharmacological Reconditioning of Marginal Donor Rat Lungs Using Inhibitors of Peroxynitrite and Poly (ADP-ribose) Polymerase During Ex Vivo Lung Perfusion

BACKGROUND

Donor lungs obtained after prolonged warm ischemia (WI) may be unsuitable for transplantation due to the risk of reperfusion injury, but could be reconditioned using ex-vivo lung perfusion (EVLP). Key processes of reperfusion injury include the formation of reactive oxygen species (ROS)/nitrogen species (RNS) and the activation of poly(adenosine diphosphate-ribose) polymerase (PARP). We explored whether rat lungs obtained after WI could be reconditioned during EVLP using the ROS/RNS scavenger Mn(III)-tetrakis (4-benzoic acid) porphyrin chloride (MnTBAP) or the PARP inhibitor 3-aminobenzamide (3-AB).

METHODS

Rat lungs obtained after 3 hours cold ischemia (CI group, control), or 1 hour WI plus 2 hours CI (WI group) were placed in an EVLP circuit for normothermic perfusion for 3 hours. Lungs retrieved after WI were treated or not with 3-AB (1 mg/mL) or MnTBAP (0.3 mg/mL), added to the perfusate. Measurements included physiological variables (lung compliance, vascular resistance, oxygenation capacity), lung weight gain, levels of proteins, lactate dehydrogenase, protein carbonyl (marker of ROS), 3-nitrotyrosine (marker of RNS), poly(adenosine diphosphate-ribose) (PAR, marker of PARP activation) and IL-6, in the bronchoalveolar lavage or the lung tissue, and histology.

RESULTS

In comparison to the CI group, the lungs from the WI group displayed higher protein carbonyls, 3-nitrotyrosine, PAR, lactate dehydrogenase and proteins in bronchoalveolar lavage, lung weight gain, perivascular edema, as well as reduced static compliance, but similar oxygenation. All these alterations were markedly attenuated by 3-AB and MnTBAP.

CONCLUSIONS

After EVLP, lungs obtained after WI exhibit oxidative stress, PARP activation, and tissue injury, which are suppressed by pharmacological inhibitors of ROS/RNS and PARP.

Organ donation protocols

Organ transplantation improves survival and quality of life in patients with end-organ failure. Waiting lists continue to grow across the world despite remarkable advances in the transplantation process, from the creation of public engagement campaigns to the development of critical pathways for the timely identification, referral, approach, and treatment of the potential organ donor. The pathophysiology of dying triggers systemic changes that are intimately related to organ viability. The intensive care management of the potential organ donor optimizes organ function and improves the donation yield, representing a significant step in reducing the mismatch between organ supply and demand. Different beliefs and cultures reflect diverse legislations and donation practices amongst different countries, creating a challenge to standardized practices. Maintaining public trust is necessary for continued progress in organ donation and transplantation, hence the urge for a joint effort in creating uniform protocols that ensure transparent practices within the medical community.

Principi e indicazioni dell’assistenza circolatoria e respiratoria extracorporea in chirurgia toracica

In origine, l’extracorporeal membrane oxygenation (ECMO) era una tecnica di assistenza respiratoria che utilizzava uno scambiatore gassoso a membrana. Per estensione, l’ECMO è diventata una tecnica respiratoria e cardiopolmonare utilizzata in caso di deficit respiratorio e/o cardiaco nell’attesa della restaurazione della funzione deficitaria o di un eventuale trapianto. Il supporto emodinamico può essere parziale o totale. Gli accessi vascolari possono essere periferici o centrali. Questo tipo di assistenza utilizza il concetto di circolazione extracorporea (CEC) sanguigna che in epoca moderna si è estesa con l’utilizzo di polmoni artificiali a membrana. Il circuito di base è semplice e comprende una pompa, un ossigenatore (che permette al sangue di caricarsi di O₂ e di eliminare CO₂) e delle vie d’accesso (una di drenaggio e una di reinfusione). La sua attuazione è facile, veloce e può essere avviata al letto del malato. Il miglioramento delle attrezzature, una migliore conoscenza delle tecniche e delle indicazioni, e le politiche di salute pubblica hanno reso popolare questa tecnica. Alcuni centri di chirurgia toracica la utilizzano di routine come assistenza alla realizzazione di un intervento terapeutico (soprattutto trapianto) assieme a team di rianimazione per il trattamento della sindrome da distress respiratorio acuto. Nel quadro della malattia polmonare dell’adulto, l’idea principale è quella di sviluppare il concetto di strategia minimalista con l’uso di una CEC adiuvante parziale – più che sostitutiva totale – che permetterebbe il recupero metabolico ad integrum del paziente. Nei prossimi anni, i progressi della tecnologia e dell’ingegneria così come le conoscenze approfondite permetteranno il miglioramento della prognosi dei pazienti colpiti da deficit respiratorio sotto assistenza meccanica.

Current status and problems of lung transplantation in Japan

Lung transplantation has been performed worldwide and recognized as an effective treatment for patients with various end-stage lung diseases. Shortage of lung donors is one of the main obstacles in most of the countries, especially in Japan. Every effort has been made to promote organ donation during the past 20 years. In 2010, Japanese transplant low was revised so that the family of the brain dead donors can make a decision for organ donation. Since then, the number of cadaveric lung donor has increased by 5-fold. However, the average waiting time is still more than 800 days resulting in considerable number of deaths on the waiting list. Lung transplantation in the use of donation after cardiac death (DCD) has now been increasingly performed in Europe, Australia and North America with promising results. However, controlled death is not permitted in Japan making it difficult to accept this strategy. Use of marginal donors is one of the strategies for organ shortage. In Japan, the rate of lung usage is now well over 60% because of careful donor management by medical consultants and aggressive use of marginal donors. Living-donor lobar lung transplantation (LDLLT) has been developed to offset the mismatch between supply and demand for those patients awaiting cadaveric lung transplantation (CLT) and it is often the most realistic option for very ill patients. Between 1998 and 2015, lung transplantation has been performed in 464 patients (55 children, 419 adults) at 9 lung transplant centers in Japan. CLT was performed in 283 patients (61%) and LDLLT was performed in 181 patients (39%). The 5-year survival was 72.3% and 71.6%, respectively. Of note, only seven children received CLT. In conclusion, lung transplantation in Japan has grown significantly with excellent results but the shortage of cadaveric lung donor remains to be an important unsolved problem. LDLLT is often the only realistic option for very ill patients especially for children.

Successful Transplantation of Lungs From an Uncontrolled Donor After Circulatory Death Preserved In Situ by Alveolar Recruitment Maneuvers and Assessed by Ex Vivo Lung Perfusion

We developed a protocol to procure lungs from uncontrolled donors after circulatory determination of death (NCT02061462). Subjects with cardiovascular collapse, treated on scene by a resuscitation team and transferred to the emergency room, are considered potential donors once declared dead. Exclusion criteria include unwitnessed collapse, no-flow period of >15 min and low flow >60 min. After death, lung preservation with recruitment maneuvers, continuous positive airway pressure, and protective mechanical ventilation is applied to the donor. After procurement, ex vivo lung perfusion (EVLP) is performed. From November 2014, 10 subjects were considered potential donors; one of these underwent the full process of procurement, EVLP, and transplantation. The donor was a 46-year-old male who died because of thoracic aortic dissection. Lungs were procured 4 h and 48 min after death, and deemed suitable for transplantation after EVLP. Lungs were then offered to a rapidly deteriorating recipient with cystic fibrosis (lung allocation score [LAS] 46) who consented to the transplant in this experimental setting. Six months after transplantation, the recipient is in good condition (forced expiratory volume in 1 s 85%) with no signs of rejection. This protocol allowed procurement of lungs from an uncontrolled donor after circulatory determination of death following an extended period of warm ischemia.