Organ Utilization Rates from Non-Ideal Donors for Solid Organ Transplant in the United States

Background: Non-ideal donors provide acceptable allografts and may expand the donor pool. This study evaluates donor utilization across solid organs over 15-years in the United States. Methods: We analyzed the OPTN STAR database to identify potential donors across three donor eras: 2005-2009, 2010-2014, and 2015-2019. Donors were analyzed by a composite Donor Utilization Score (DUS), comprised of donor age and comorbidities. Outcomes of interest were overall and organ-specific donor utilization. Descriptive analyses and multivariable logistic regression modeling were performed. p-values < 0.01 considered significant. Results: Of 132,465 donors, 32,710 (24.7%) were identified as non-ideal donors (NID), based on a DUS ≥ 3. Compared to ideal donors (ID), NID were older (median 56 years, IQR 51-64 years vs. 35 years, 22-48 years, p < 0.001) and more frequently female (44.3% vs. 39.1%, p < 0.001), Black (22.1% vs. 14.6%, p < 0.001) and obese (60.7% vs. 19.6%, p < 0.001). The likelihood of overall DBD utilization from NID increased from Era 1 to Era 2 (OR 1.227, 95% CI 1.123-1.341, p < 0.001) and Era 3 (OR 1.504, 1.376-1.643, p < 0.001), while DCD donor utilization in NID was not statistically different across Eras. Compared to Era 1, the likelihood of DBD utilization from NID for kidney transplantation was lower in Era 2 (OR 0.882, 0.822-0.946) and Era 3 (OR 0.938, 0.876-1.004, p = 0.002). The likelihood of NID utilization increased in Era 3 compared to Era 1 for livers (OR 1.511, 1.411-1.618, p < 0.001), hearts (OR 1.623, 1.415-1.862, p < 0.001), and lungs (OR 2.251, 2.011-2.520, p < 0.001). Conclusions: Using a universal definition of NID across organs, NID donor utilization is increasing; however, use of DUS may improve resource utilization in identifying donors at highest likelihood for multi-organ donation.

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.

Developing machine learning models to predict primary graft dysfunction after lung transplantation

Primary graft dysfunction (PGD) is the leading cause of morbidity and mortality in the first 30 days after lung transplantation. Risk factors for the development of PGD include donor and recipient characteristics, but how multiple variables interact to impact the development of PGD and how clinicians should consider these in making decisions about donor acceptance remain unclear. This was a single-center retrospective cohort study to develop and evaluate machine learning pipelines to predict the development of PGD grade 3 within the first 72 hours of transplantation using donor and recipient variables that are known at the time of donor offer acceptance. Among 576 bilateral lung recipients, 173 (30%) developed PGD grade 3. The cohort underwent a 75% to 25% train-test split, and lasso regression was used to identify 11 variables for model development. A K-nearest neighbor's model showing the best calibration and performance with relatively small confidence intervals was selected as the final predictive model with an area under the receiver operating characteristics curve of 0.65. Machine learning models can predict the risk for development of PGD grade 3 based on data available at the time of donor offer acceptance. This may improve donor-recipient matching and donor utilization in the future.

History of Lung Transplantation

Lung transplantation remains the only available therapy for many patients with end-stage lung disease. The number of lung transplants performed has increased significantly, but development of the field was slow compared with other solid-organ transplants. This delayed growth was secondary to the increased complexity of transplanting lungs; the continuous needs for surgical, anesthetics, and critical care improvements; changes in immunosuppression and infection prophylaxis; and donor management and patient selection. The future of lung transplant remains promising: expansion of donor after cardiac death donors, improved outcomes, new immunosuppressants targeted to cellular and antibody-mediated rejection, and use of xenotransplantation or artificial lungs.

Assessing donor organ quality according to recipient characteristics in lung transplantation

OBJECTIVE

There is a shortage of donor lungs relative to need, but overall donor organ utilization remains low. The most common reason for refusal is organ quality, but the standards applied to selection vary. In this study we sought to characterize differences in lung utilization according to quality across several clinically distinct recipient pools.

METHODS

Data on donor lungs recovered (April 2006 to September 2019) were extracted from the Scientific Registry of Transplant Recipients database. Organs were classified as ideal, standard, or extended quality according to their poorest metric among selected parameters. Subanalyses were performed on the basis of procedure type, age, lung allocation score, era, and alternative definitions of extended quality. Recipient traits and survival according to organ quality were assessed.

RESULTS

Of 156,022 lungs analyzed during the study period, 25,777 (16.5%) were transplanted. There was no difference in quality distribution for single and bilateral transplants. Young candidates were more likely to receive ideal (14.7% vs 12.3%) or standard (9.5% vs 8.2%) lungs, but not extended lungs (75.9% vs 79.5%; all P < .01). Absolute differences in distribution according to lung allocation score quartile were small (<2%). Extended quality donor utilization increased over time. Survival according to donor category was similar at 1 and 3 years post transplant in unadjusted and Cox regression analyses.

CONCLUSIONS

Extended quality lungs comprise an increasing share of transplants in a national sample. Organ selection varies according to recipient age and lung allocation score. However, absolute differences in quality distribution are small, and adverse effects on outcomes are limited to organs with multiple extended qualifying characteristics.

A prediction model to determine the untapped lung donor pool outside of the DonateLife network in Victoria

Lung transplantation is limited by a lack of suitable lung donors. In Australia, the national donation organisation (DonateLife) has taken a major role in optimising organ donor identification. However, the potential outside the DonateLife network hospitals remains uncertain. We aimed to create a prediction model for lung donation within the DonateLife network and estimate the untapped lung donors outside of the DonateLife network. We reviewed all deaths in the state of Victoria's intensive care units using a prospectively collected population-based intensive care unit database linked to organ donation records. A logistic regression model derived using patient-level data was developed to characterise the lung donors within DonateLife network hospitals. Consequently, we estimated the expected number of lung donors in Victorian hospitals outside the DonateLife network and compared the actual number. Between 2014 and 2018, 291 lung donations occurred from 8043 intensive care unit deaths in DonateLife hospitals, while only three lung donations occurred from 1373 ICU deaths in non-DonateLife hospitals. Age, sex, postoperative admission, sepsis, neurological disease, trauma, chronic respiratory disease, lung oxygenation and serum creatinine were factors independently associated with lung donation. A highly discriminatory prediction model with area under the receiver operator characteristic curve of 0.91 was developed and accurately estimated the number of lung donors. Applying the model to non-DonateLife hospital data predicted only an additional five lung donors. This prediction model revealed few additional lung donor opportunities outside the DonateLife network, and the necessity of alternative and novel strategies for lung donation. A donor prediction model could provide a useful benchmarking tool to explore organ donation potential across different jurisdictions, hospitals and transplanting centres.

Machine Perfusion for Human Heart Preservation: A Systematic Review

Currently, static cold storage (SCS) of hearts from donations after brainstem death remains the standard clinically. However, machine perfusion (MP) is considered an approach for donor organ management to extend the donor pool and/or increase the utilization rate. This review summarizes and critically assesses the available clinical data on MP in heart transplantation. We searched Medline (PubMed), Cochrane, Embase, and clinicaltrials.gov, along with reference lists of the included publications and identified 40 publications, including 18 articles, 17 conference abstracts, and five ongoing clinical trials. Two types of MP were used: hypothermic MP (HMP) and normothermic MP (NMP). Three studies evaluated HMP, and 32 evaluated NMP. Independent of the system, MP resulted in clinical outcomes comparable to traditional SCS. However, NMP seemed especially beneficial for high-risk cases and donation after circulatory death (DCD) hearts. Based on currently available data, MP is non-inferior to standard SCS. Additionally, single-centre studies suggest that NMP could preserve the hearts from donors outside standard acceptability criteria and DCD hearts with comparable results to SCS. Finally, HMP is theoretically safer and simpler to use than NMP. If a machine malfunction or user error occurs, NMP, which perfuses a beating heart, would have a narrower margin of safety. However, further well-designed studies need to be conducted to draw clear conclusions.

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.

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.

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.

Acute Rejection in the Modern Lung Transplant Era

Acute cellular rejection (ACR) remains a common complication after lung transplantation. Mortality directly related to ACR is low and most patients respond to first-line immunosuppressive treatment. However, a subset of patients may develop refractory or recurrent ACR leading to an accelerated lung function decline and ultimately chronic lung allograft dysfunction. Infectious complications associated with the intensification of immunosuppression can also negatively impact long-term survival. In this review, we summarize the most recent evidence on the mechanisms, risk factors, diagnosis, treatment, and prognosis of ACR. We specifically focus on novel, promising biomarkers which are under investigation for their potential to improve the diagnostic performance of transbronchial biopsies. Finally, for each topic, we highlight current gaps in knowledge and areas for future research.

A three-tier system for evaluation of organ procurement organizations' willingness to pursue and utilize nonideal donor lungs

Lungs from "nonideal," but acceptable donors are underutilized; however, organ procurement organization (OPO) metrics do not reflect the extent to which OPO-specific practices contribute to these trends. We developed a comprehensive system to evaluate nonideal lung donor avoidance, or risk aversion among OPOs. Adult donors in the UNOS registry who donated ≥1 organ for transplantation between 2007 and 2018 were included. Nonideal donors had any of age>50, smoking history ≥20 pack-years, PaO₂ /FiO₂ ratio ≤350, donation after circulatory death, or increased risk status. OPO-level risk aversion in donor pursuit, consent attainment, lung recovery, and transplantation was assessed. Among 83916 donors, 70372 (83.9%) were nonideal. Unadjusted OPO-level rates of nonideal donor pursuit ranged from 81 to 100%. In a three-tier system of overall risk aversion, tier 3 OPOs (least risk-averse) had the highest rates of nonideal donor pursuit, consent attainment, lung recovery, and transplantation. Tier 1 OPOs (most risk-averse) had the lowest rates of donor pursuit, consent attainment, and lung recovery, but higher rates of transplantation compared to tier 2 OPOs (moderately risk-averse). Risk aversion varies among OPOs and across the donation process. OPO evaluations should reflect early donation process stages to best differentiate over- and underperforming OPOs and encourage optimal OPO-specific performance.

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.

Impact of extended-criteria donor lungs according to preoperative recipient status and age in lung transplantation

Background

Organ donor shortage remains as one of the limiting factors for lung transplantation. Given the increase in waiting time, preoperative condition has worsened and affects surgical outcomes. This study aimed to evaluate the immediate postoperative and long-term outcomes of lung transplantation in extended-criteria donor (ECD) lungs compared with standard-criteria donor (SCD) lungs.

Methods

A total of 246 patients who had undergone double-lung transplantation during the study period were enrolled. SCD was defined based on the following characteristics age <55 years, <20 pack-years smoking history, and PaO₂/fraction of O₂ ratio >300 mmHg. Organ donors who do not fulfill these criteria were classified as ECD. Pre- and postoperative data for outcomes and survival data were analyzed.

Results

ECD showed significant association with extracorporeal membrane oxygenation weaning in the operating room (hazard ratio [HR], 0.531; 95% confidence interval [CI], 0.291–0.970; P=0.039) considering recipient’s age and status at operation. The ECD group showed comparable survival rate with the SCD group (HR, 1.413; 95% CI, 0.885–2.255; P=0.148), with adjustment of other factors. However, when the recipient had Korean Network for Organ Sharing (KONOS) status 0 at the time of transplantation (HR, 1.662; 95% CI, 1.025–2.568; P=0.039), G3 primary graft dysfunction at 72 hours after surgery (HR, 2.508; 95% CI, 1.416–4.440; P=0.002) was a risk factor that decreased survival.

Conclusions

The outcome of ECD is not inferior to that of SCD. Therefore, ECD lung should be considered a potential donor organ following active donor management rather than a contraindication of transplantation in highly selected recipients.

Donor-related Risk Factors Associated With Increased Mortality After Lung Transplant

BACKGROUND

Lung transplant is a surgical procedure for end-stage lung disease. Many factors related to lung donors influence the outcome of transplant. The main aim of this single-center study was to assess which donor-related and procedure-related factors would influence the 30-day or hospital mortality of the recipients.

METHODS

This retrospective study group consisted of 110 donor-recipient pairs undergoing lung transplant between 2012 and 2017 (group 1) and 2018 and 2019 (group 2) in Silesian Center for Heart Diseases. Both groups of donor- and procedure-related factors were included in the analysis: oxygenation index at reporting of the donor, time donor spent in the intensive care unit (ICU), presence of cardiac arrest while being in the ICU, donor age, type of transplant, cumulative ischemia time, duration of the operation, and time of mechanical ventilation.

RESULTS

The type of surgery was significantly associated with an increase in the chance of death within 30 days. Patients who underwent single lung transplant had a 20.217 times greater chance of dying within 30 days than patients after double lung transplant (interquartile range, 2.116-193.125).

CONCLUSIONS

Single lung transplant increases the risk of death during the first 30 days after lung transplant, and using lungs from older donors may increase the rate of hospital mortality. Oxygenation index, sudden cardiac arrest of the donors, and donor time spent in the ICU do not impact the short-term mortality of lung graft recipients.

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.

Hanging donor lungs give good short-, mid- and long-term results in lung transplantation

BACKGROUND

Hanging donors are considered as marginal donors and frequently unsuitable for lung transplantation. However, there is no evidence of higher lung transplantation (LTx) morbidity-mortality with lungs providing by hanging donor.

METHODS

Between January 2010 and July 2015, we performed a retrospective study at Foch hospital. We aimed to assess whether hanging donor grafts are suitable for lung transplantation.

RESULTS

A total of 299 LTx were performed. Subjects were allocated to a hanging group (HG) (n = 20) and a control group (CG) (n = 279). Donor and recipient characteristics did not differ. Primary graft dysfunction (PGD) at 72 hours was comparable in both groups (P = .75). The median duration of postoperative mechanical ventilation (1 [range, 0-84] vs 1 [range, 0-410] day, P = .35), the hospital length of stay (31 days [20-84] vs 32 days [12-435], P = .36) did not differ between the two groups. No statistically significant difference was found in 1-year and 5-year survival between the HG (83% and 78%) and the CG (86% and 75%), P = .85.

CONCLUSION

We believe that hanging donors should be considered as conventional donors with particular caution in the final evaluation of the graft and in perioperative management.

Outcomes and risk factors identification in urgent lung transplantation: a multicentric study

Background

In rapidly lung deteriorating patients, urgent lung transplantation (ULT) seems the only definitive therapy. Few publications on this topic report conflicting results, putting a word of caution about ULT programs.

Methods

A national ULT program was introduced in 2010: patients on mechanical support may be transplanted with the first available graft. We reviewed the experience of three national center, focusing on post-operative outcomes after ULT.

Results

Ten patients (17.5%) died awaiting transplantation, while 47 underwent LT with a median urgent waiting list time of 6 days. Pre-operatively, 4.3% of patients were supported only by mechanical ventilation (MV), 55.3% by extracorporeal membrane oxygenation (ECMO) and the remaining 40.4% by both. The main indication was cystic fibrosis (64%). Median recipient lung allocation score was 72. In-hospital mortality was 19%. MV and ECMO median duration of 7 and 3 days, respectively while intensive care unit (ICU) and hospital stay were 20 and 46 days, respectively. At long-term, 1- and 3-year survival rate were 74% and 70%, respectively. Highly impact risk factors for in-hospital mortality were both presence and duration of preoperative veno-arterial ECMO and pre-transplant C-reactive protein level.

Conclusions

ULT program allows transplantation in a significant percentage of patients with acceptable results. Pre-operative recipient selection is mandatory to improve clinical outcomes.

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.

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

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

Use of taurolidine in lung transplantation for cystic fibrosis and impact on bacterial colonization

OBJECTIVES

The presence of bacterial colonization that causes chronic pulmonary infections in cystic fibrosis (CF) patients remains a key issue before lung transplantation. We sought to assess the impact of intraoperative taurolidine lavage on bacterial colonization and long-term outcomes following lung transplantation in CF patients.

METHODS

Between 2007 and 2013, 114 CF patients underwent lung transplantation at our institute, and taurolidine 2% bronchial lavage was applied in a substantial proportion of patients (n = 42). A detailed analysis of donor and recipient bacterial colonization status in treatment and control groups and their impact on outcome was performed.

RESULTS

The proportion of recipients colonized with Pseudomonas aeruginosa was lower in the taurolidine group at 3 months (P < 0.001) and at 1 year (P = 0.053) postoperatively, despite no differences before transplant (P = 1.000). Moreover, a complete eradication of Burkholderia cepacia and Stenotrophomonas maltophilias colonizations could be achieved in the taurolidine group, whereas in the non-taurolidine group, persistent B. cepacia and S. maltophilias colonizations were observed. Early outcome in the taurolidine group was superior regarding fraction of expired volume in 1 s at 3 and 6 months after surgery with 74.5 ± 14.6 vs 60.4 ± 17.5 (P < 0.001) and 80.6 ± 16.9 vs 67.2 ± 19.4 (P = 0.005) percent of predicted values, respectively. In terms of long-term overall survival (P = 0.277) and freedom from bronchiolitis obliterans syndrome (P = 0.979), both groups were comparable.

CONCLUSIONS

Taurolidine might be associated with a reduced proportion of CF patients colonized with multiresistant pathogens, particularly with P. aeruginosa. Long-term results should be further assessed in larger multicentre trials.

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.

Sequence of refusals for donor quality, organ utilization, and survival after lung transplantation

BACKGROUND

Lung donor utilization rates remain low, with many organs refused for donor quality. However, some centers have successfully transplanted these organs despite multiple refusals for donor quality (RDQs) by other centers. We hypothesized that the number of refusals due to donor quality does not impact post-transplant outcomes.

METHODS

Lung transplants (LTxs) from 2006 to 2015, identified using the United Network for Organ Sharing (UNOS) database, were matched against the potential transplant recipient (PTR) data set by donor identification. Transplants were categorized into 2 groups: low RDQ (0 to 3 RDQs) and high RDQ (>3 RDQs). Post-transplant survival and predictors for high RDQ were observed using Kaplan‒Meier and logistic regression analyses, respectively.

RESULTS

Of 10,126 adult (>18 years) LTxs, 77% had at least 1 RDQ, with a median of 4 RDQs. Post-transplant 1-year survival was similar for both the low and high RDQ groups (p = 0.49). Furthermore, groups of recipients who received donors with an increasing number of RDQs (>3, >6, or >10) also had similar post-transplant 1-year survival (p = 0.77). Treatment for rejection within 1 year and intubation at 72 hours post-transplant were higher in the high RDQ group (p < 0.01). An inverse relationship was identified between the number of RDQs and likelihood of utilization. After 10 RDQs, the likelihood of utilization varied significantly by donor characteristics.

CONCLUSIONS

Lung transplant survival is not associated with number of refusals due to donor quality. When determining whether an organ is suitable for transplant, the number of refusals due to donor quality should not influence one's decision, especially in this era of limited donor supply.

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.

State of the Art in Pediatric Lung Transplantation

Pediatric lung transplantation is a highly specialized therapy for end-stage pulmonary disease in children, and is performed in only a handful of transplant centers around the world. Advancement in the field has been made on many fronts in recent years, including in public policy and organ allocation strategies, donor selection and management, emerging technologies for donor lung rehabilitation and bridge-to-transplant support of listed candidates, and ongoing refinement of surgical techniques. Despite this progress, children continue to suffer discrepant waitlist mortality and longer waiting times than their adult counterparts, and face special challenges of donor availability and size matching. Here, we assess the current state of the art in pediatric lung transplantation, reviewing progress made to date and further opportunities to improve care for this unique group of patients.

Optimizing the Use of Available Lungs

BACKGROUND

Organ transplantation, the treatment of choice in organ failure, is penalized by the lack of organs. Because the increase in the number of donors is not proportional throughout the different age groups, there is no increase in lung transplantations. The aim of this work was to analyze the use of available lungs and evaluate strategies that may help increase transplantations.

METHODS

We analyzed the activity of lung transplantation in 2015, divided into various allocation programs. We also examined the surplus organs, in particular, their origin, their destination, their offer's outcome, the characteristics of the donor and the proposed organ, and the reasons for rejection.

RESULTS

In 2015, 112 lung transplantations were performed: 66 (68.9%) with regional organs, 46 (41.1%) with extraregional organs; 21 (45.6%) of these were allocated as emergencies/return, and 25 (54.4%) as surplus (19 in the North macroarea, 6 in the South macroarea). The number of surplus lungs was 148: 67 from the North macroarea, 71 from the South macroarea, and 10 from abroad. No organ procured in the North macroarea was transplanted in the South macroarea, whereas 6 lungs coming from the South macroarea were transplanted in the North.

CONCLUSIONS

The acceptance criteria are not the same in different transplant centers and they include not only clinical parameters, but also ischemia time and composition of the waiting list at the time of the offer, quality and accessibility of the intensive care units where the donor is located, and organizational reasons. Offering organs which can not be transplanted within the region to other centers, without clinical foreclosures is a system that increases transplant activities by maximizing the available resources.

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.

Zonal organ allocation system and its impact on long-term outcomes after lung transplantation: a propensity score matched analysis†

OBJECTIVE

Zonal organ allocation system comprises organ procurement by teams within a specific geographical area of each retrieval team. Therefore, in a substantial number of cases organs are retrieved by 'foreign' teams and are sent for transplantation to the implanting centre. The aim of this study was to assess the impact of zonal organ allocation system on early- and long-term outcomes after lung transplantation (LTx).

METHODS

Included were 331 consecutive patients who underwent LTx performed at Harefield Hospital between January 2007 and January 2015. Recipients were divided into two groups depending on the organ retrieval team: 204 (61.6%) patients were transplanted using lungs procured by our institutional team (institutional group), whereas 127 (38.4%) organs were retrieved by other teams (external group) from experienced transplant centres in the UK. To exclude selection bias and other confounders, a 1:1 propensity score-based matching procedure was performed resulting in a total number of 238 donors and recipients who were well matched for baseline characteristics. The primary end-points were overall survival after LTx and freedom from bronchiolitis obliterans syndrome (BOS). Secondary end-points were perioperative clinical characteristics as well as adverse events that occurred over the follow-up.

RESULT

After propensity score matching all donor characteristics and all baseline recipient characteristics were statistically similar between the two groups. In terms of early postoperative results, both groups were statistically comparable. However, there was a trend towards higher incidence of primary graft dysfunction in the external group (P = 0.054). Regarding long-term results with up to 7 years of follow-up, the overall survival also appeared to be poorer in the external group; however, this difference did not reach statistical significance. The freedom from BOS over the long-term follow was significantly poorer in the external group (P = 0.040).

CONCLUSION

Despite excellent early outcomes the zonal allocation system might be associated with significantly poorer long-term outcomes in terms of freedom from BOS after bilateral LTx. Further research is needed to find the underlying factors leading to these results.

Moving Back to the Future: Use of Organ Care System Lung for Lobectomy Before Lobar Lung Transplantation

BACKGROUND Lung transplantation remains the gold standard treatment for patients with end-stage lung disease. Lobar lung transplantation allows for transplantation of size-mismatch donor lungs in small recipients; however, donor lung volume reduction represents a challenging surgical technique. In this paper we present our initial experience with bilateral lobectomy in donor lungs before lobar lung transplantation using normothermic perfusion on the Organ Care System (OCS) Lung. MATERIAL AND METHODS Specifics of the surgical technique for donor lung instrumentation on the OCS, lobar dissection on the OCS, and right and left donor lobectomies are presented in detail. RESULTS Potential advantages of the use of the OCS for lobectomy for lobar lung transplantation are described in this section. Donor lung volume reduction utilizing OCS appeared to be easier and safer compared to the conventional cold storage technique, due to continuous perfusion of the lungs with blood and well-distended vessels that offer the feel of live lobectomy. Moreover, the OCS represents a platform for donor organ assessment and optimization of its function before transplantation. CONCLUSIONS Donor lung volume reduction was safe and feasible utilizing the OCS, which could be a useful tool for volume reduction in cases of size mismatch. Further research is needed to evaluate early and long-term results after lobar lung transplantation using the OCS in clinical studies.

Donors with a prior history of cardiac surgery are a viable source of lung allografts

OBJECTIVES

End-stage lung disease continues to rise despite the lack of suitable lung donors, limiting the numbers of lung transplants performed each year. Expanded donor criteria, use of donation after cardiac death donors and the advent of ex vivo lung perfusion have resulted only in a slight increase in donor lung utilization. Organ donors with prior cardiac surgery (DPCS) present risks and technical challenges; however, they may be a potential source of suitable lung allografts with an experienced procurement surgeon. We present our experience having evaluated potential lung donors with a prior history of cardiac surgery, resulting in successful transplant outcomes.

METHODS

This is a single-institution retrospective review of brain-dead organ donors that were evaluated for lung donation in the period 2012-15. Donor and recipient characteristics were collected. Post-lung transplant survival was recorded.

RESULTS

From 2012 to 2015, 259 donors were evaluated, 12 with a prior history of cardiac surgery of which 4 had coronary artery bypass, 3 had aortic root replacement, 2 had aortic valve replacement, 1 pulmonary embolectomy, 1 two-time reoperative valve replacement and 1 paediatric congenital ventricular septal defect repair. DPCS, 6/12 (50% dry run) provided suitable allografts generating six single-lung transplants (three right and three left, 1 donor provided twin single-lung transplants) and one double-lung transplant. Interval between cardiac surgery and procurement for those rejected was median 5840 (IQR 2350-8640) days and interval for the donors that provided allografts was median 438 (IQR 336-1095) days (Mann-Whitney, P = 0.07). Recipient 1-year survival from DPCS is 100%. Recipient 1-year survival was 92% in allografts explanted from donors with no prior cardiac surgery (2012-13).

CONCLUSION

To date, this is the largest single-centre experience using lung allografts from brain-dead DPCS. Our experience shows despite predicted technical difficulties, with good communication between thoracic and abdominal teams, successful transplant outcomes are possible, when surgeons with experience in reoperative cases are sent for lung procurements.