A decade of extended-criteria lung donors in a single center: was it justified?

Validation of a novel donor lung scoring system based on the updated lung Composite Allocation Score

Lung transplantation (LTx) continues to have lower rates of long-term graft survival compared with other organs. Additionally, lung utilization rates from brain-dead donors remain substantially lower compared with other solid organs, despite a growing need for LTx and the significant risk of waitlist mortality. This study aims to examine the effects of using a combination of the recently described novel lung donor (LUNDON) acceptability score and the newly adopted recipient lung Composite Allocation Score (CAS) to guide transplantation. We performed a review of nearly 18 000 adult primary lung transplants from 2015-2022 across the US with retroactive calculations of the CAS value. The medium-CAS group (29.6-34.5) had superior 1-year posttransplant survival. Importantly, the combination of high-CAS (> 34.5) recipients with low LUNDON score (≤ 40) donors had the worst survival at 1 year compared with any other combination. Additionally, we constructed a model that predicts 1-year and 3-year survival using the LUNDON acceptability score and CAS values. These results suggest that caution should be exercised when using marginally acceptable donor lungs in high-priority recipients. The use of the LUNDON score with CAS value can potentially guide clinical decision-making for optimal donor-recipient matches for LTx.

Lung Transplantation Outcomes in Recipients Aged 70 Years or Older and the Impact of Center Volume

OBJECTIVE

To evaluate trends and outcomes of lung transplants (LTx) in recipients ≥ 70 years.

METHODS

We performed a retrospective analysis of the UNOS database identifying all patients undergoing LTx (May 2005-December 2022). Baseline characteristics and postoperative outcomes were compared by age (<70 years, ≥70 years) and center volume. Kaplan-Meier analyses were performed with pairwise comparisons between subgroups.

RESULTS

34,957 patients underwent LTx, of which 3236 (9.3%) were ≥70 years. The rate of LTx in recipients ≥ 70 has increased over time, particularly in low-volume centers (LVCs); consequently, high-volume centers (HVCs) and LVCs perform similar rates of LTx for recipients ≥ 70. Recipients ≥ 70 had higher rates of receiving from donor after circulatory death lungs and of extended donor criteria. Recipients ≥ 70 were more likely to die of cardiovascular diseases or malignancy, while recipients < 70 of chronic primary graft failure. Survival time was shorter for recipients ≥ 70 compared to recipients < 70 old (hazard ratio (HR): 1.36, 95% confidence interval (CI): 1.28-1.44, p < 0.001). HVCs were associated with a survival advantage in recipients < 70 (HR: 0.91, 95% CI: 0.88-0.94, p < 0.001); however, in recipients ≥ 70, survival was similar between HVCs and LVCs (HR: 1.11, 95% CI: 0.99-1.25, p < 0.08). HVCs were more likely to perform a bilateral LTx (BLT) for obstructive lung diseases compared to LVCs, but there was no difference in BLT and single LTx likelihood for restrictive lung diseases.

CONCLUSIONS

Careful consideration is needed for recipient ≥ 70 selection, donor assessment, and post-transplant care to improve outcomes. Further research should explore strategies that advance perioperative care in centers with low long-term survival for recipients ≥ 70.

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.

Primary graft dysfunction after lung transplantation

PURPOSE OF REVIEW

Primary graft dysfunction (PGD) is a clinical syndrome occurring within the first 72 h after lung transplantation and is characterized clinically by progressive hypoxemia and radiographically by patchy alveolar infiltrates. Resulting from ischemia-reperfusion injury, PGD represents a complex interplay between donor and recipient immunologic factors, as well as acute inflammation leading to alveolar cell damage. In the long term, chronic inflammation invoked by PGD can contribute to the development of chronic lung allograft dysfunction, an important cause of late mortality after lung transplant.

RECENT FINDINGS

Recent work has aimed to identify risk factors for PGD, focusing on donor, recipient and technical factors both inherent and potentially modifiable. Although no PGD-specific therapy currently exists, supportive care remains paramount and early initiation of ECMO can improve outcomes in select patients. Initial success with ex-vivo lung perfusion platforms has been observed with respect to decreasing PGD risk and increasing lung transplant volume; however, the impact on survival is not well delineated.

SUMMARY

This review will summarize the pathogenesis and clinical features of PGD, as well as highlight treatment strategies and emerging technologies to mitigate PGD risk in patients undergoing lung transplantation.

Recommendations for Evaluation and Selection of Deceased Organ Donor: Position Statement of ISCCM

There is a wide gap between patients who need transplants and the organs that are available in India. Extending the standard donation criterion is certainly important to address the scarcity of organs for transplantation. Intensivists play a major role in the success of deceased donor organ transplants. Recommendations for deceased donor organ evaluation are not discussed in most intensive care guidelines. The purpose of this position statement is to establish current evidence-based recommendations for multiprofessional critical care staff in the evaluation, assessment, and selection of potential organ donors. These recommendations will give "real-world" criteria that are acceptable in the Indian context. The aim of this set of recommendations is to both increase the number and enhance the quality of transplantable organs.

How to cite this article

Zirpe KG, Tiwari AM, Pandit RA, Govil D, Mishra RC, Samavedam S, et al. Recommendations for Evaluation and Selection of Deceased Organ Donor: Position Statement of ISCCM. Indian J Crit Care Med 2022;26(S2):S43-S50.

Primary Graft Dysfunction: The Role of Aging in Lung Ischemia-Reperfusion Injury

Transplant centers around the world have been using extended criteria donors to remedy the ongoing demand for lung transplantation. With a rapidly aging population, older donors are increasingly considered. Donor age, at the same time has been linked to higher rates of lung ischemia reperfusion injury (IRI). This process of acute, sterile inflammation occurring upon reperfusion is a key driver of primary graft dysfunction (PGD) leading to inferior short- and long-term survival. Understanding and improving the condition of older lungs is thus critical to optimize outcomes. Notably, ex vivo lung perfusion (EVLP) seems to have the potential of reconditioning ischemic lungs through ex-vivo perfusing and ventilation. Here, we aim to delineate mechanisms driving lung IRI and review both experimental and clinical data on the effects of aging in augmenting the consequences of IRI and PGD in lung transplantation.

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.

Primary graft dysfunction: what we know

Many advances in lung transplant have occurred over the last few decades in the understanding of primary graft dysfunction (PGD) though effective prevention and treatment remain elusive. This review will cover prior understanding of PGD, recent findings, and directions for future research. A consensus statement updating the definition of PGD in 2016 highlights the growing complexity of lung transplant perioperative care taking into account the increasing use of high flow oxygen delivery and pulmonary vasodilators in the current era. PGD, particularly more severe grades, is associated with worse short- and long-term outcomes after transplant such as chronic lung allograft dysfunction. Growing experience have helped identify recipient, donor, and intraoperative risk factors for PGD. Understanding the pathophysiology of PGD has advanced with increasing knowledge of the role of innate immune response, humoral cell immunity, and epithelial cell injury. Supportive care post-transplant with technological advances in extracorporeal membranous oxygenation (ECMO) remain the mainstay of treatment for severe PGD. Future directions include the evolving utility of ex vivo lung perfusion (EVLP) both in PGD research and potential pre-transplant treatment applications. PGD remains an important outcome in lung transplant and the future holds a lot of potential for improvement in understanding its pathophysiology as well as development of preventative therapies and treatment.

An Intention-to-treat View of Lung Transplantation for Interstitial Lung Disease: Successful Strategies to Minimize Waiting List and Posttransplant Mortality

BACKGROUND

Access to lung transplantation (LTx) and rates of waiting list and posttransplant mortality for patients with interstitial lung disease (ILD) remain problematic. We evaluated the outcomes of ILD patients listed for LTx at our institution.

METHODS

Between 2012 and 2018, adult patients with ILD were listed and transplanted from a donor-pool that included extended criteria and donation after circulatory-determined death donors. Patients were categorized as experiencing 1 of 4 competing events: transplant, waitlist death, delisting, or alive on waitlist. Multivariable competing risk regression analysis was performed to determine predictors of waitlist death/delisting. Posttransplant survival was analyzed using Kaplan-Meier methods.

RESULTS

Among 187 patients listed, 82% (153 of 187) underwent LTx (median time-to-transplant, 2.0 mo), whereas 16% (30 of 187) died or were delisted (median time-to-event, 1.6 mo). At 90 d, 6 mo, and 12 mo after listing, 51%, 63%, and 78% of patients had been transplanted, whereas 10%, 14%, and 16% had died or were delisted. Multivariable predictors of waitlist death/delisting were: blood group O compared to A (subdistribution hazard ratio [SHR]: 6.43, P < 0.001), shorter height (per 1 cm, SHR: 1.11, P < 0.001), hospitalization at listing (SHR: 3.98, P = 0.002), and reduced 6-min-walk test distance (per 50 m, SHR: 1.28, P = 0.001). Among LTx recipients, 24% (36 of 153) underwent single LTx. Donor lungs were 58% (88 of 153) extended-criteria, inclusive of 24% (37 of 153) circulatory-determined death. Ninety-day and 1-, 3-, and 5-y retransplant free survival were 97% ± 1%, 92% ± 2%, 81% ± 4%, and 69% ± 6%.

CONCLUSIONS

Patients with ILD require a rapid transit to LTx after listing. Despite this, the vast majority of ILD patients in this study reached LTx with excellent early and midterm outcomes.

Analysis of sex-based differences in clinical and molecular responses to ischemia reperfusion after lung transplantation

Background

Sex and hormones influence immune responses to ischemia reperfusion (IR) and could, therefore, cause sex-related differences in lung transplantation (LTx) outcomes. We compared men’s and women’s clinical and molecular responses to post-LTx IR.

Methods

In 203 LTx patients, we used the 2016 International Society for Heart and Lung Transplantation guidelines to score primary graft dysfunction (PGD). In a subgroup of 40 patients with blood samples collected before LTx (T0) and 6, 24, 48 (T48), and 72 h (T72) after lung reperfusion, molecular response to IR was examined through serial analysis of circulating cytokine expression.

Results

After adjustment, women had less grade 3 PGD than men at T48, but not at T72. PGD grade decreased from T0 to T72 more often in women than men. The evolution of PGD (the difference in mean PGD between T72 and T0) was greater in men. However, the evolution of IL-2, IL-7, IL-17a, and basic fibroblast growth factor levels was more often sustained throughout the 72 h in women. In the full cohort, we noted no sex differences in secondary clinical outcomes, but women had significantly lower peak lactate levels than men across the 72 h.

Conclusions

Men and women differ in the evolution of PGD and cytokine secretion after LTx: Women have a more sustained proinflammatory response than men despite a greater reduction in PGD over time. This interaction between cytokine and PGD responses warrants investigation. Additionally, there may be important sex-related differences that could be used to tailor treatment during or after transplantation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-021-01900-y.

A translational rat model for ex vivo lung perfusion of pre-injured lungs after brain death

The process of brain death (BD) detrimentally affects donor lung quality. Ex vivo lung perfusion (EVLP) is a technique originally designed to evaluate marginal donor lungs. Nowadays, its potential as a treatment platform to repair damaged donor lungs is increasingly studied in experimental models. Rat models for EVLP have been described in literature before, yet the pathophysiology of BD was not included in these protocols and prolonged perfusion over 3 hours without anti-inflammatory additives was not achieved. We aimed to establish a model for prolonged EVLP of rat lungs from brain-dead donors, to provide a reliable platform for future experimental studies. Rat lungs were randomly assigned to one of four experimental groups (n = 7/group): 1) healthy, directly procured lungs, 2) lungs procured from rats subjected to 3 hours of BD and 1 hour cold storage (CS), 3) healthy, directly procured lungs subjected to 6 hours EVLP and 4), lungs procured from rats subjected to 3 hours of BD, 1 hour CS and 6 hours EVLP. Lungs from brain-dead rats showed deteriorated ventilation parameters and augmented lung damage when compared to healthy controls, in accordance with the pathophysiology of BD. Subsequent ex vivo perfusion for 6 hours was achieved, both for lungs of healthy donor rats as for pre-injured donor lungs from brain-dead rats. The worsened quality of lungs from brain-dead donors was evident during EVLP as well, as corroborated by deteriorated ventilation performance, increased lactate production and augmented inflammatory status during EVLP. In conclusion, we established a stable model for prolonged EVLP of pre-injured lungs from brain-dead donor rats. In this report we describe tips and pitfalls in the establishment of the rat EVLP model, to enhance reproducibility by other researchers.

Donor quality assessment and size match in lung transplantation

Careful donor quality assessment and size match can impact long-term survival in lung transplantation. With this article, we review the conceptual and practical aspects of the preoperative donor lung quality assessment and size matching.

Aggressive pursuit and utilization of non-ideal donor lungs does not compromise post-lung transplant survival

BACKGROUND

Organ procurement organizations (OPOs) vary in willingness to pursue and utilize non-ideal donor lungs; implications of these practices for lung transplant (LTx) recipients remain unclear. We examined associations between OPO-level behavior toward non-ideal donors and post-LTx outcomes.

METHODS

Adult lung donors and corresponding adult first-time LTx recipients in the 2008-2019 UNOS registry were included. Non-ideal donors had any of age > 50, smoking history ≥20 pack-years, PaO₂ /FiO₂ ratio ≤350, donation after circulatory death, or increased risk status. OPOs were classified as least, moderately, or most aggressive based on non-ideal donor pursuit, consent attainment, lung recovery, and transplantation. Post-transplant outcomes were compared among aggressiveness strata.

RESULTS

Of 22,795 recipients, 6229 (27.3%), 8256 (36.2%), and 8310 (36.5%) received lungs from least, moderately, and most aggressive OPOs, respectively. Moderately aggressive OPOs had the highest recipient rates of pre-discharge acute rejection, grade 3 primary graft dysfunction, postoperative extracorporeal membrane oxygenation, and longest lengths of stay. After adjustment, moderately and most aggressive OPOs had similar risks of recipient mortality as least aggressive OPOs.

CONCLUSIONS

The most and least aggressive OPOs achieve similar patient survival and short-term post-LTx outcomes. Aggressive pursuit and utilization of non-ideal donor lungs by less aggressive OPOs would likely expand the donor pool, without compromising recipient outcomes.

Advances in lung transplantation for interstitial lung diseases

PURPOSE OF REVIEW

Lung transplantation (LTx) is increasingly used as ultimate treatment modality in end-stage interstitial lung diseases (ILDs). This review aims to give an overview of the latest evolutions in this field.

RECENT FINDINGS

In the last two years, important new findings regarding LTx outcomes in specific ILD entities have been reported. More data are available on optimization of pre-LTx management of ILD patients especially with regard to pretransplant antifibrotic treatment.

SUMMARY

LTx is the only treatment option with curative intent for ILDs and is increasingly used for this indication. Several studies have now reported adequate outcomes in different ILD entities, although outcome is shown to be affected by underlying telomeropathies. As new studies could not replicate inferior survival with single compared with double LTx, both options remain acceptable. ILD specialists can beneficially impact on post-LTx outcome by optimizing pre-LTx management: corticosteroids should be avoided, antifibrotics should be initiated whenever possible and BMI and nutritional status optimized, rehabilitation and depression-screening strategies should be implemented in all LTx candidates, as these interventions may all improve postlung transplant survival.

Primary graft dysfunction

PURPOSE OF REVIEW

Primary graft dysfunction (PGD) is a devastating complication in the acute postoperative lung transplant period, associated with high short-term mortality and chronic rejection. We review its definition, pathophysiology, risk factors, prevention, treatment strategies, and future research directions.

RECENT FINDINGS

New analyses suggest donation after circulatory death and donation after brain death donors have similar PGD rates, whereas donors >55 years are not associated with increased PGD risk. Recipient pretransplant diastolic dysfunction and overweight or obese recipients with predominant abdominal subcutaneous adipose tissue have increased PGD risk. Newly identified recipient biomarkers and donor and recipient genes increase PGD risk, but their clinical utility remains unclear. Mixed data still exists regarding cold ischemic time and PGD risk, and increased PGD risk with cardiopulmonary bypass remains confounded by transfusions. Portable ex vivo lung perfusion (EVLP) may prevent PGD, but its use is limited to a handful of centers. Although updates to current PGD treatment are lacking, future therapies are promising with targeted therapy and the use of EVLP to pharmacologically recondition donor lungs.

SUMMARY

There is significant progress in defining PGD and identifying its several risk factors, but effective prevention and treatment strategies are needed.

Short- and Long-Term Impact of Smoking Donors in Lung Transplantation: Clinical and Pathological Analysis

Background: The use of smoking donors (SD) is one strategy to increase the organ pool for lung transplantation (LT), but the benefit-to-risk ratio has not been demonstrated. This study aimed to evaluate the impact of SD history on recipient outcomes and graft alterations. Methods: LTs in 293 patients were retrospectively reviewed and divided into non-SD (n = 225, group I), SD < 20 pack-years (n = 45, group II), and SD ≥ 20 pack-years (n = 23, group III) groups. Moreover, several lung donor biopsies before implantation (equally divided between groups) were evaluated, focusing on smoking-related lesions. Correlations were analyzed between all pathological data and smoking exposure, along with other clinical parameters. Results: Among the three groups, donor and recipient characteristics were comparable, except for higher Oto scores and age in group III. Group III showed a longer intensive care unit (ICU) and hospital stay compared with the other two groups. This finding was confirmed when SD history was considered as a continuous variable. However, survival and other mid- and long-term major outcomes were not affected by smoking history. Finally, morphological lesions did not differ between the three groups. Conclusions: In our study, SDs were associated with a longer post-operative course, without affecting graft aspects or mid- and long-term outcomes. A definition of pack-years cut-off for organ refusal should be balanced with the other extended criteria donor factors.

Residual endotoxin induces primary graft dysfunction through ischemia/reperfusion-primed alveolar macrophages

Despite the widespread use of antibiotics, bacterial pneumonias in donors strongly predispose to the fatal syndrome of primary graft dysfunction (PGD) following lung transplantation. We report that bacterial endotoxin persists in human donor lungs after pathogen is cleared with antibiotics and is associated with neutrophil infiltration and PGD. In mouse models, depletion of tissue-resident alveolar macrophages (TRAMs) attenuated neutrophil recruitment in response to endotoxin as shown by compartmental staining and intravital imaging. Bone marrow chimeric mice revealed that neutrophils were recruited by TRAM through activation of TLR4 in a MyD88-dependent manner. Intriguingly, low levels of endotoxin, insufficient to cause donor lung injury, promoted TRAM-dependent production of CXCL2, increased neutrophil recruitment, and led to PGD, which was independent of donor NCMs. Reactive oxygen species (ROS) increased in human donor lungs starting from the warm-ischemia phase and were associated with increased transcription and translocation to the plasma membrane of TLR4 in donor TRAMs. Consistently, scavenging ROS or inhibiting their production to prevent TLR4 transcription/translocation or blockade of TLR4 or coreceptor CD14 on donor TRAMs prevented neutrophil recruitment in response to endotoxin and ameliorated PGD. Our studies demonstrate that residual endotoxin after successful treatment of donor bacterial pneumonia promotes PGD through ischemia/reperfusion-primed donor TRAMs.

National Trends in Extended Criteria Donor Utilization and Outcomes for Lung Transplantation

BACKGROUND

Extended criteria donor (ECD) for lung transplantation (LTx) have been implemented due to the donor organ shortage. The impact on recipient survival is under investigation. We report trends in the use of extended criteria lungs in the modern era and its association with survival outcomes using a large national database.

METHODS

We performed a retrospective analysis of all adult LTx from May 2005 to December 2018 using the United Network for Organ Sharing database. ECD were defined by 2 or more variances from standard criteria: age ≥ 55 years, pO2 ≤ 300, pack years ≥ 20, diabetes, purulent bronchoscopy, blood infection, or abnormal chest radiographs. Transplant centers were dichotomized based on volume. Recipient survival was analyzed using lung allocation score as a covariate.

RESULTS

Of 24,888 LTx, 80% had extended criteria; 42% had 2 or more extensions and were deemed ECD in this analysis. Both LTx volume (2005: 1352; 2018: 2495) and use of ECD (2005: 27% ECD, 2018: 50% ECD) have increased over the study period. Survival of LTx recipients has steadily increased (2005: 82% 1-year survival in 2005; 2017: 90% 1-year survival). High-volume centers (>47 annual LTx) utilized ECD in 46% of transplants compared with 40% ECD among other centers. Recipients of ECD and standard criteria organs had no difference in 1-year survival.

CONCLUSIONS

Donor supply limits the number of LTx performed. Extension of donor criteria has occurred alongside increased overall LTx volume. Use of ECD did not compromise 30-day, 90-day, nor 1-year survival. Further studies are warranted to define long-term outcomes.

Procedure Preference and Intention-to-Treat Outcomes after Listing for Lung Transplantation among U.S. Adults. A Cohort Study

RATIONALE

Bilateral lung transplantation is widely used to treat chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD), on the basis of an expectation of improved survival after transplantation. Yet, waiting list mortality is higher while awaiting bilateral transplantation. The net effect of procedure preference on overall survival is unknown.

OBJECTIVES

To determine whether an unrestricted procedure preference is associated with improved overall outcomes after listing for lung transplantation.

METHODS

We performed a retrospective cohort study of 12,155 adults with COPD or ILD listed for lung transplantation in the United States between May 4, 2005, and December 31, 2014. We defined a "restricted" procedure preference as listing for "bilateral transplantation only" and an "unrestricted" procedure preference as listing for any combination of bilateral or single lung transplantation. We used a composite "intention-to-treat" primary outcome that included events both before and after transplantation, defined as the number of days between listing and death, removal from the list for clinical deterioration, or retransplantation.

RESULTS

In adjusted analyses, an unrestricted procedure preference was associated with a 3% lower rate of the primary intention-to-treat outcome in COPD (adjusted hazard ratio [aHR], 0.97; 95% confidence interval [CI], 0.89-1.07) and a 1% higher rate in ILD (aHR, 1.01; 95% CI, 0.94-1.08). There was no convincing evidence that these associations varied by age, disease severity, or the use of mechanical support. Among those with ILD and concomitant severe pulmonary hypertension, an unrestricted preference was associated with a 17% increased rate of the primary outcome (aHR, 1.17; 95% CI, 0.99-1.39). An unrestricted preference was consistently associated with lower rates of death or removal from the list for clinical deterioration and with higher rates of transplantation. Graft failure rates were similar among those listed with restricted and unrestricted preferences.

CONCLUSION

When considering outcomes both before and after transplantation, we found no evidence that patients with COPD or ILD benefit from listing for bilateral lung transplantation compared with listing for a more liberal procedure preference. An unrestricted listing strategy for suitable candidates may increase the number of transplants performed without impacting overall survival.

Impact of donor lung quality on post-transplant recipient outcome in the Lung Allocation Score era in Eurotransplant - a historical prospective study

The aim of this study was to investigate whether there is an impact of donation rates on the quality of lungs used for transplantation and whether donor lung quality affects post-transplant outcome in the current Lung Allocation Score era. All consecutive adult LTx performed in Eurotransplant (ET) between January 2012 and December 2016 were included (N = 3053). Donors used for LTx in countries with high donation rate were younger (42% vs. 33% ≤45 years, P < 0.0001), were less often smokers (35% vs. 46%, P < 0.0001), had more often clear chest X-rays (82% vs. 72%, P < 0.0001), had better donor oxygenation ratios (20% vs. 26% with PaO₂ /FiO₂  ≤ 300 mmHg, P < 0.0001), and had better lung donor score values (LDS; 28% vs. 17% with LDS = 6, P < 0.0001) compared with donors used for LTx in countries with low donation rate. Survival rates for the groups LDS = 6 and ≥7 at 5 years were 69.7% and 60.9% (P = 0.007). Lung donor quality significantly impacts on long-term patient survival. Countries with a low donation rate are more oriented to using donor lungs with a lesser quality compared to countries with a high donation rate. Instead of further stretching donor eligibility criteria, the full potential of the donor pool should be realized.

Ex-vivo lung perfusion versus standard protocol lung transplantation-mid-term survival and meta-analysis

Background

While extended criteria lung donation has helped expand the lung donor pool, utilization of lungs from donors of at least one other solid organ is still limited to around 15-30%. Ex-vivo lung perfusion (EVLP) offers the ability to expand the number of useable lung grafts through assessment and reconditioning of explanted lungs, particularly those not initially meeting criteria for transplantation. This meta-analysis aimed to examine the mid- to long-term survival and other short-term outcomes of patients transplanted with EVLP-treated lungs versus standard/cold-storage protocol lungs.

Methods

Literature search of ten medical databases was conducted for original studies involving "ex-vivo lung perfusion" and "EVLP". Included articles were assessed by two independent researchers, survival data from Kaplan-Meier curves digitized, and individual patient data imputed to conduct aggregated survival analysis. Meta-analyses of suitably reported outcomes were conducted using a random-effects model.

Results

Thirteen studies met inclusion criteria, with a total of 407 EVLP lung transplants and 1,765 as per standard/cold storage protocol. One study was a randomized controlled trial while the remainder were single-institution cohort series of varying design. The majority of donor lungs were from brain death donors, with EVLP lungs having significantly worse PaO₂/FiO₂ ratio and significantly greater rate of abnormal chest X-ray. Aggregated survival analysis of all included studies revealed no significant survival difference for EVLP or standard protocol lungs (hazard ratio 1.00; 95% confidence interval: 0.79-1.27, P=0.981). Survival at 12, 24, and 36 months for the EVLP cohort was 84%, 79%, and 74%, respectively. Survival at 12, 24, and 36 months for the standard protocol cohort was 85%, 79%, and 73%, respectively. Meta-analysis did not find a significant difference in risk of 30-day mortality or primary graft dysfunction grade 3 at 72 hours between cohorts.

Conclusions

There was no significant difference in mid- to long-term survival of EVLP lung transplant patients when compared to standard protocol donor lungs. The incidence of 30-day mortality and primary graft dysfunction grade 3 at 72 hours did not differ significantly between groups. EVLP offers the potential to increase lung donor utilization while providing similar short-term outcomes and mid- to long-term survival.

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.

Lung Transplantation and Precision Medicine

Lung transplantation is an accepted therapeutic option for end-stage lung diseases. Its history starts in the 1940s, initially hampered by early deaths due to perioperative problems and acute rejection. Improvement of surgical techniques and the introduction of immunosuppressive drugs resulted in longer survival. Chronic lung allograft dysfunction (CLAD), a new complication appeared and remains the most serious complication today. CLAD, the main reason why survival after lung transplantation is impaired compared to other solid-organ transplantations is characterized by a gradually increasing shortness of breath, reflected in a deterioration of pulmonary function status, respiratory insufficiency and possibly death.

Transplantation of donor lungs with pulmonary embolism - a retrospective study

Lung transplantation from donors with fulminant pulmonary arterial embolism as a cause of death remains controversial. An analysis was performed comparing preoperative characteristics and outcomes of 25 donors with a primary diagnosis of pulmonary arterial embolism to 1085 recipients of donor lungs without pulmonary arterial embolism. No early functional impairment of donor lungs with pulmonary embolism was detectable as depicted by the incidence of primary graft dysfunction immediately after surgery (P = 0.66), 24 (P = 0.79), 48 (P = 0.99) and 72 h (P = 0.99) after transplantation. Pulmonary function testing at 1 year (P = 0.003) and at last outpatient control (P < 0.05) showed superior results in the cohort receiving lungs from donors with pulmonary embolism. Incidence of chronic lung allograft dysfunction (CLAD) showed no difference within the first year after lung transplantation, however, 5 year-CLAD free survival was superior in recipients (70.4% vs. 55.1%, P = 0.006) of donor lungs with pulmonary embolism. Overall survival was similar in both groups. Lungs from donors with fulminant pulmonary embolism prior to brain death can safely be used for lung transplantation without impairing postoperative outcomes. Lung function testing shows favorable midterm results in recipients of donor lungs with pulmonary embolism.

Early Graft Dysfunction after Lung Transplantation

PURPOSE OF REVIEW

Primary graft dysfunction is an acute lung injury syndrome occurring immediately following lung transplantation. This review aims to provide an overview of the current understanding of PGD, including epidemiology, immunology, clinical outcomes and management.

RECENT FINDINGS

Identification of donor and recipient factors allowing accurate prediction of PGD has been actively pursued. Improved understanding of the immunology underlying PGD has spurred interest in identifying relevant biomarkers. Work in PGD prediction, severity stratification and targeted therapies continue to make progress. Donor expansion strategies continue to be pursued with ex vivo lung perfusion playing a prominent role. While care of PGD remains supportive, ECMO has established a prominent role in the early aggressive management of severe PGD.

SUMMARY

A consensus definition of PGD has allowed marked advances in research and clinical care of affected patients. Future research will lead to reliable predictive tools, and targeted therapeutics of this important syndrome.

Deceased organ donation activity and efficiency in Switzerland between 2008 and 2017: achievements and future challenges

BACKGROUND

Various actions have been taken during the last decade to increase the number of organs from deceased donors available for transplantation in Switzerland. This study provides an overview on key figures of the Swiss deceased organ donation and transplant activity between 2008 and 2017. In addition, it puts the evolution of the Swiss donation program's efficiency in relation to the situation in the neighboring countries.

METHODS

This study is an analysis of prospective registry data, covering the period from 1 January 2008 to 31 December 2017. It includes all actual deceased organ donors (ADD) in Switzerland. Donor data were extracted from the Swiss Organ Allocation System. The "donor conversion index" (DCI) methodology and data was used for the comparison of donation program efficiency in Switzerland, Germany, Austria, Italy and France.

RESULTS

During the study period there were 1116 ADD in Switzerland. The number of ADD per year increased from 91 in 2008 to 145 in 2017 (+ 59%). The reintroduction of the donation after cardiocirculatory death (DCD) program in 2011 resulted in the growth of annual percentages of DCD donors, reaching a maximum of 27% in 2017. The total number of organs transplanted from ADD was 3763 (3.4 ± 1.5 transplants per donor on average). Of these, 48% were kidneys (n = 1814), 24% livers (n = 903), 12% lungs (n = 445), 9% hearts (n = 352) and 7% pancreata or pancreatic islets (n = 249). The donation program efficiency assessment showed an increase of the Swiss DCI from 1.6% in 2008 to 2.7% in 2017 (+ 69%). The most prominent efficiency growth was observed between 2012 and 2017. Even though Swiss donation efficiency increased during the study period, it remained below the DCI of the French and Austrian donation programs.

CONCLUSION

Swiss donation activity and efficiency grew during the last decade. The increased donation efficiency suggests that measures implemented so far were effective. The lower efficiency of the Swiss donation program, compared to the French and Austrian programs, may likely be explained by the lower consent rate in Switzerland. This issue should be addressed in order to achieve the goal of more organs available for transplantation.

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.

Stereotactic ablative radiotherapy for early-stage lung cancer following double lung transplantation

BACKGROUND

Development of primary lung cancer in donor lung post-lung transplantation is very rare, with few described cases. The safety of stereotactic ablative radiotherapy (SABR) for early-stage lung cancer arising from donor lung is unclear.

CASE PRESENTATION

Herein, we present a case of a patient with a Stage IB adenocarcinoma arising from donor lung 8 years post-double lung transplantation, which was performed due to advanced emphysema. The patient was ineligible for surgical management due to chronic lung allograft dysfunction, which significantly compromised pulmonary function. Full dose SABR was delivered with curative intent after a discussion with the patient. The patient tolerated the treatment well, with one episode of subacute toxicity that resolved with treatment. There was no evidence of recurrence at 15 months post-treatment and the patient's pulmonary function did not deviate from the pre-SABR baseline.

CONCLUSIONS

SABR appears feasible for medically-inoperable early-stage primary lung adenocarcinoma in the setting of previous double-lung transplantation.

Extended-criteria donors in lung transplantation in Switzerland: an evaluation of two adapted lung donor scores

AIM Various scoring systems aim to assess the quality of organs donated for transplantation on the basis of patient characteristics, clinical examination and laboratory results. How well such scoring systems reflect the practice in lung transplantation in Switzerland has never been studied. Therefore, we evaluated two scoring systems for their ability to predict whether or not donor lungs are accepted by the two Swiss lung transplant centres. METHODS We retrospectively analysed patient data of adult deceased organ donors in Switzerland between 1 July 2007 and 30 June 2014. Included were all donors from whom at least one organ was transplanted. We evaluated two lung donor quality scores, the multicentre-developed Eurotransplant donor score (EDS), and the single-centre-developed Zurich donor score (ZDS). Both scores were slightly adapted to be applicable to Swiss deceased organ donor data. We evaluated whether these scores can predict whether lungs were transplanted or refused by Swiss transplant centres, using univariate logistic regression. We further assessed their discriminative power by calculating the area under the receiver operating characteristic curve (AUC). RESULTS Of the 635 donors included in our analysis, 295 (46%) were accepted as lung donors by one of the two lung transplant centres in Switzerland. Our analysis showed that both scores can predict whether or not a donor lung is likely to be accepted for transplantation in Switzerland. As the score value of a donor increases, the odds of the lung being transplanted significantly decreases (odds ratio [OR] 0.58, 95% confidence interval [CI] 0.51–0.65 for the adapted EDS; OR 0.35, 95% CI 0.28–0.43 for the adapted ZDS). This effect is slightly more pronounced in the adapted ZDS than in the adapted EDS. The discriminatory power of the scores from the AUC was 0.719 (95% CI 0.680–0.758) for the adapted EDS, and 0.723 (95% CI 0.681–0.760) for the adapted ZDS, which for both was deemed fair discrimination. CONCLUSIONS Both scoring systems are able to predict whether or not donor lungs are accepted by the two Swiss lung transplant centres. As an alternative to adapting an established scoring system, a national lung quality score could be derived de novo. This could be based on a logistic regression analysis including the most relevant donor characteristics. However, such a new score would need to be validated on an independent sample and ideally tested for its predictive value in terms of post-transplantation outcome.

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.

Short- and Long-term Outcomes After Lung Transplantation From Circulatory-Dead Donors: A Single-Center Experience

BACKGROUND

Donation after cardiac death (DCD) to overcome the donor organ shortage is well accepted in the clinical setting, although long-term outcome after DCD lung transplantation (LTx) remains largely unknown.

METHODS

In this retrospective study, DCD LTx recipients (n = 59) were compared with a cohort of donation after brain death (DBD) LTx recipients (n = 331) transplanted between February 2007 and September 2013; follow-up was until January 1, 2016. Short-term (duration of mechanical ventilation, intensive care unit stay, hospital stay, and highest primary graft dysfunction score within 72 hours) and long-term (chronic lung allograft dysfunction-free and overall survival) follow-up were compared over a median follow-up of 50.5 (±3.7) months for DCD and 66.8 (±1.5) months for DBD.

RESULTS

There were no differences between groups with regard to patient characteristics: age (P = 0.78), underlying disease (P = 0.30) and type of type of LTx (P = 0.10), except sex where more males were transplanted with a DCD donor (62.7%) vs (48.3%, P = 0.048). There was no difference in time on mechanical ventilation (P = 0.59), intensive care unit stay (P = 0.74), highest primary graft dysfunction score (P = 0.67) and hospital stay (P = 0.99). Moreover, chronic lung allograft dysfunction-free (P = 0.86) and overall survival (P = 0.15) did not differ between the DBD and DCD groups.

CONCLUSIONS

In our experience, both short- and long-term outcomes in DCD lung recipients are comparable to that of DBD lung recipients. Therefore, DCD LTx can be considered a safe strategy that significantly increased our transplant activity.

Evaluation and Management of the Potential Lung Donor

The expansion of the donor lung pool has involved an evidence-driven redefinition of acceptable donors. Proceeding with transplantation with an acceptable rather than ideal donor depends on specific patient-related and organ-related risk factors as well as the severity of recipient illness. Although the physiologic optimization of brain-dead donors has not changed significantly in recent years, the use of donor management protocols has improved procurement rates. Ex vivo lung perfusion is an increasingly viable strategy to recondition lungs that would otherwise fall below the acceptable threshold for transplant. Ex vivo perfusion trials for preservation of standard donor lungs are ongoing.

Five myths about variable selection

Multivariable regression models are often used in transplantation research to identify or to confirm baseline variables which have an independent association, causally or only evidenced by statistical correlation, with transplantation outcome. Although sound theory is lacking, variable selection is a popular statistical method which seemingly reduces the complexity of such models. However, in fact, variable selection often complicates analysis as it invalidates common tools of statistical inference such as P-values and confidence intervals. This is a particular problem in transplantation research where sample sizes are often only small to moderate. Furthermore, variable selection requires computer-intensive stability investigations and a particularly cautious interpretation of results. We discuss how five common misconceptions often lead to inappropriate application of variable selection. We emphasize that variable selection and all problems related with it can often be avoided by the use of expert knowledge.