Effect of ischemic time on survival in clinical lung transplantation

Extended ischemic times during ex vivo lung perfusion is not associated with increased mortality

BACKGROUND

The purpose of this study was to identify the association of increasing ischemic times in recipients who receive lungs evaluated by ex vivo lung perfusion (EVLP) and their association with outcomes following lung transplantation.

METHODS

Lung transplant recipients who received an allograft evaluated by EVLP were identified from the United Network for Organ Sharing (UNOS) Database from 2016-2023. Recipients were stratified into three groups based on total ischemic time (TOT): short TOT (STOT, 0 to <7 h), medium TOT (MTOT, 7> to <14 h), and long TOT (LTOT, +14 h). The groups were assessed with comparative statistics and Kaplan-Meier methods. A Cox regression was created to determine the association of ischemic time in EVLP donors and long-term mortality.

RESULTS

Recipients in the LTOT group had significantly longer length of stay and post-operative extracorporeal membrane use at 72 h (p < 0.05 for both). Additionally, they had nonsignificant increases in rate of stroke (4.7%, p = 0.05) and primary graft dysfunction grade 3 (PGD3, 27.5%, p = 0.082). However, there was no significant difference in hospital mortality or mid-term survival (p > 0.05 for both). On multivariable analysis, ischemic time was not associated with increased mortality whereas increasing recipient age, preoperative ECMO use and donation after circulatory death donors were (p < 0.05 for all).

CONCLUSIONS

If EVLP technology is available, under certain circumstances, surgeons should not be dissuaded from using an allograft with extended ischemic time.

Xenotransplantation of Mitochondria: A Novel Strategy to Alleviate Ischemia-Reperfusion Injury during Ex Vivo Lung Perfusion

Ischemia-reperfusion injury (IRI) plays a crucial role in the development of primary graft dysfunction (PGD) following lung transplantation. A promising novel approach to optimize donor organs before transplantation and reduce the incidence of PGD is mitochondrial transplantation. In this study, we explored the delivery of isolated mitochondria in 4 hour ex vivo lung perfusion (EVLP) before transplantation as a means to mitigate IRI. To provide a fresh and viable source of mitochondria, as well as to streamline the workflow without the need for donor muscle biopsies, we investigated the impact of autologous, allogeneic and xenogeneic mitochondrial transplantation. In the xenogeneic settings, isolated mitochondria from mouse liver were utilized while autologous and allogeneic sources came from pig skeletal muscle biopsies. Treatment with mitochondrial transplantation increased the P/F ratio and reduced pulmonary peak pressure of the lungs during EVLP, compared to lungs without any mitochondrial transplantation, indicating IRI mitigation. Extensive investigations using advanced light and scanning electron microscopy did not reveal evidence of acute rejection in any of the groups, indicating safe xenotransplantation of mitochondria. Future work is needed to further explore this novel therapy for combating IRI in lung transplantation, where xenotransplantation of mitochondria may serve as a fresh, viable source to reduce IRI.

Cold ischemia time alters cell-type specific senescence leading to loss of cellular integrity in mouse lungs

Purpose: Ischemia-reperfusion injury (IRI) is a major challenge in lung transplantation often causing graft dysfunction and chronic airway illnesses in recipients. To prevent potential transplant related complications, strict guidelines were put in place to choose viable donor lungs with minimal risk of IRI. These regulations deem most of the donor organs unfit for transplant which then are donated for research to understand the mechanisms of health and diseases in human. However, resected organs that are being transported undergo cold ischemia that can negatively affect the tissue architecture and other cellular functions under study. Thus, it is important to assess how cold ischemia time (CIT) affects the physiological mechanism. In this respect, we are interested in studying how CIT affects cellular senescence in normal aging and various pulmonary pathologies. We thus hypothesized that prolonged CIT exhibits cell-type specific changes in lung cellular senescence in mice. Methods: Lung lobes from C57BL/6J (n = 5-8) mice were harvested and stored in UW Belzer cold storage solution for 0, 4-, 9-, 12-, 24-, and 48-h CIT. Lung cellular senescence was determined using fluorescence (C12FdG) assay and co-immunolabelling was performed to identify changes in individual cell types. Results: We found a rapid decline in the overall lung cellular senescence after 4-h of CIT in our study. Co-immunolabelling revealed the endothelial cells to be most affected by cold ischemia, demonstrating significant decrease in the endothelial cell senescence immediately after harvest. Annexin V-PI staining further revealed a prominent increase in the number of necrotic cells at 4-h CIT, thus suggesting that most of the cells undergo cell death within a few hours of cold ischemic injury. Conclusions: We thus concluded that CIT significantly lowers the cellular senescence in lung tissues and must be considered as a confounding factor for mechanistic studies in the future.

Enhancing Donor Transport Success: Lessons From the Iranian Experiences

OBJECTIVES

Organ transplant is a complex process that involves various medical, legal, and social factors. The organ demand continues to outweigh the supply, leading to global challenges in the expansion of transplant programs. Ischemic time is crucial for the viability of organs, and efforts are being made to reduce transport time to improve transplant success rates. The viability and quality of the organ for transplant depends on minimized ischemic time.

MATERIALS AND METHODS

A new method is presently being implemented in Iran, in which, instead of transfer of organs, leading to reduced organ quality due to ischemic time, the donors themselves are transferred to transplant centers with the help of a trained team after brain death is confirmed and with the consent of the family. During the transfer process, an anesthesiologist or nurse specialized in donor care performs the relevant pretransplant procedures.

RESULTS

The successful transportation of donors to centers for organ procurement requires meticulous planning, trained personnel, and adherence to safety protocols. Quality assurance measures, including audits and safety protocols, are in place to ensure the timely and safe delivery of donated organs. Ultimately, improvements in the transportation process for organ donation can enhance transplant success.

CONCLUSIONS

Successful transportation of donors to organ procurement units is crucial for reducing ischemic time and improving the success rate and quality of organ transplants. Careful planning, communication, and collaboration among health care professionals are necessary for the timely and safe delivery of donated organs.

Impact of Time of Day on Surgical Outcomes After Lung Transplantation (Night-Time Lung Transplant)

BACKGROUND

Surgical outcomes have been linked to the technical and cognitive abilities of an exhausted surgical team. In parallel, advancements in preservation have led to the proposal of daytime lung transplants. We sought to investigate whether time of day is associated with outcomes in lung transplants.

METHODS

Data on 30,404 lung transplants from 2005 to 2021 were obtained from the United Network for Organ Sharing database. Patients were categorized based on the time of surgery with early-hours defined as donor cross-clamp between 10 pm and 3 am, and Cox regression models for 90-day and long-term mortality were made to assess the risk according to time of transplant and covariates. Additionally, the Cox modeling was repeated with donor cross-clamp and the estimated reperfusion time of day as continuous functions.

RESULTS

Among 30,404 transplants, 20.7% (6295) were performed during early hours. No significant difference was found between the 2 groups in unadjusted 90-day and long-term mortality (log-rank, P = .176 and .363, respectively), and results were unchanged when adjusting for covariates (P = .233 and .738, respectively). However, when examining donor cross-clamp time and reperfusion time as continuous variables in separate multivariable analyses, we observed significant associations with 90-day mortality (P = .002 and .022, respectively). Notably, lower mortality rates were observed for donor clamp-times between 8 am and 1 pm and estimated reperfusion times between 1 pm and 6 pm.

CONCLUSIONS

Although binary categorizations of the time of day of lung transplants did not show a significant impact on short- or long-term survival, continuous-time analyses demonstrated that certain times during the day were associated with favorable short-term survival.

Analysis of Primary Graft Dysfunction (PGD) Risk Factors in Lung Transplantation (LuTx) Patients

BACKGROUND

Primary graft dysfunction (PGD) is a form of acute lung injury (ALI) that occurs within 72 h after lung transplantation (LuTx) and is the most common early complication of the procedure. PGD is diagnosed and graded based on the ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen and chest X-ray results. PGD grade 3 increases recipient mortality and the chance of chronic lung allograft dysfunction (CLAD).

METHOD

The aim of this retrospective study was to identify new PGD risk factors. The inclusion criteria were met by 59 patients, who all received transplants at the same center between 2010 and 2018. Donor data were taken from records provided by the Polish National Registry of Transplantation and analyzed in three variants: PGD 1-3 vs. PGD 0, PGD 3 vs. PGD 0 and PGD 3 vs. PGD 0-2.

RESULTS

A multiple-factor logistic regression model was used to identify decreasing recipient age; higher donor BMI and higher donor central venous pressure (CVP) for the PGD (of the 1-3 grade) risk factor.

CONCLUSIONS

Longer cold ischemia time (CIT) and higher donor CVP proved to be independent risk factors of PGD 3.

Impact of Prolonged Cold Ischemia Time on Long-Term Survival in Lung Transplant Recipients

BACKGROUND

Cold ischemia time (CIT) influences short- and long-term outcomes in lung transplant recipients. Most studies proved that prolonged CIT causes increased mortality. This study aimed to investigate the impact of prolonged CIT on patient survival time after lung transplantation (LTx).

METHODS

The retrospective study group consisted of 139 patients who underwent double LTx in a single center between January 2018 and August 2022. Prolonged ischemic time (PIT) was defined as total ischemic time >6 hours and divided into smaller time intervals according to increasing PIT (6-8, 8-10, 10-12, >12 hours). The assessed outcomes were 1- and 4-year survival.

RESULTS

Among the study group, PIT was observed in 98% (n = 137), and its average value was 10.33 hours. The prolonged CIT of 6 to 8 hours occurred in 10% (n = 14), 8 to 10 hours in 34% (n = 47), 10 to 12 hours in 36% (n = 49), and >12 hours in 20% (n = 27). In a comparison of 1-year survival between the PIT 6- to 10-hour group and the >10-hour arm (88% vs 78%), the difference was not statistically significant (P > .05).

CONCLUSION

PIT is a risk factor for reduced long-term survival in LTx recipients. Increasing PIT may be associated with higher mortality at 1 and 4 years. All efforts to reduce the duration of ischemic time can benefit patient survival after LTx.

Controlled Hypothermic Storage for Lung Preservation: Leaving the Ice Age Behind

Controlled hypothermic storage (CHS) is a recent advance in lung transplantation (LTx) allowing preservation at temperatures higher than those achieved with traditional ice storage. The mechanisms explaining the benefits of CHS compared to conventional static ice storage (SIS) remain unclear and clinical data on safety and feasibility of lung CHS are limited. Therefore, we aimed to provide a focus review on animal experiments, molecular mechanisms, CHS devices, current clinical experience, and potential future benefits of CHS. Rabbit, canine and porcine experiments showed superior lung physiology after prolonged storage at 10°C vs. ≤4°C. In recent molecular analyses of lung CHS, better protection of mitochondrial health and higher levels of antioxidative metabolites were observed. The acquired insights into the underlying mechanisms and development of CHS devices allowed clinical application and research using CHS for lung preservation. The initial findings are promising; however, further data collection and analysis are required to draw more robust conclusions. Extended lung preservation with CHS may provide benefits to both recipients and healthcare personnel. Reduced time pressure between procurement and transplantation introduces flexibility allowing better decision-making and overnight bridging by delaying transplantation to daytime without compromising outcome.

The effect of allograft ischemic time on outcomes following bilateral, single, and reoperative lung transplantation

OBJECTIVE

To determine whether allograft ischemic times affect outcomes following bilateral, single, and redo lung transplantation.

METHODS

A nationwide cohort of lung transplant recipients from 2005 through 2020 was examined using the Organ Procurement and Transplantation Network registry. The effects of standard (<6 hours) and extended (≥6 hours) ischemic times on outcomes following primary bilateral (n = 19,624), primary single (n = 688), redo bilateral (n = 8461), and redo single (n = 449) lung transplantation were analyzed. A priori subgroup analysis was performed in the primary and redo bilateral-lung transplant cohorts by further stratifying the extended ischemic time group into mild (≥6 and <8 hours), moderate (≥8 and <10 hours), and long (≥10 hours) subgroups. Primary outcomes included 30-day mortality, 1-year mortality, intubation at 72 hours' posttransplant, extracorporeal membrane oxygenation (ECMO) support at 72 hours' posttransplant, and a composite variable of intubation or ECMO at 72 hours' posttransplant. Secondary outcomes included acute rejection, postoperative dialysis, and hospital length of stay.

RESULTS

Recipients of allografts with ischemic times ≥6 hours experienced increased 30-day and 1-year mortality following primary bilateral-lung transplantation, but increased mortality was not observed following primary single, redo bilateral, or redo single-lung transplants. Extended ischemic times correlated with prolonged intubation or increased postoperative ECMO support in the primary bilateral, primary single, and redo bilateral-lung transplant cohorts but did not affect these outcomes following redo single-lung transplantation.

CONCLUSIONS

Since prolonged allograft ischemia correlates with worse transplant outcomes, the decision to use donor lungs with extended ischemic times must consider the specific benefits and risks associated with individual recipient factors and institutional expertise.

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

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

Analysis of Donor to Recipient Pathogen Transmission in Relation to Cold Ischemic Time and Other Selected Aspects of Lung Transplantation-Single Center Experience

BACKGROUND

Infections are one of the leading causes of death in the early postoperative period after lung transplantation (LuTx).

METHODS

We analyzed 59 transplantations and culture results of the donor bronchial aspirates (DBA), graft endobronchial swabs (GES), and recipient cultures (RC) before and after the procedure (RBA). We correlated the results with a cold ischemic time (CIT), recipient intubation time, and length of stay in the hospital and intensive care unit (ICU), among others.

RESULTS

CIT of the first and second lungs were 403 and 541 min, respectively. Forty-two and eighty-three percent of cultures were positive in DBA and GES, respectively. Furthermore, positive results were obtained in 79.7% of RC and in 33.9% of RBA. Longer donor hospitalization was correlated with Gram-negative bacteria isolation in DBA. Longer CIT was associated with Gram-positive bacteria other than Staphylococcus aureus in GES and it resulted in longer recipient stay in the ICU. Furthermore, longer CIT resulted in the development of the new pathogens in RBA.

CONCLUSION

Results of GES brought more clinically relevant information than DBA. Donor hospitalization was associated with the occurrence of Gram-negative bacteria. Positive cultures of DBA, GES, and RBA were not associated with recipient death.

Favorable, arduous or fatal postoperative pathway within 90 days of lung transplantation

INTRODUCTION

The maximum gain in quality of life after lung transplantation (LT) is expected between six months and one year after LT, as the occurrence of chronic lung allograft dysfunction may mask the beneficial effects beyond one year. Thus, the postoperative period could be the cornerstone of graft success. We sought to describe the factors present before postoperative admission to the ICU and associated with favorable, arduous or fatal pathway within 90 days of LT.

MATERIALS AND METHODS

We conducted a retrospective single-center study between January 2015 and December 2020. Using multinomial regression, we assessed the demographic, preoperative and intraoperative characteristics of patients associated with favorable (duration of postoperative mechanical ventilation < 3 days and alive at Day 90), arduous (duration of postoperative mechanical ventilation ≥ 3 days and alive at Day 90) or fatal (dead at Day 90) pathway within 90 days of LT.

RESULTS

A total of 269 lung transplant patients were analyzed. Maximum graft cold ischemic time ≥ 6 h and intraoperative blood transfusion ≥ 3 packed red blood cells were associated with arduous and fatal pathway at Day 90, whereas intraoperative ECMO was strongly associated with fatal pathway.

CONCLUSION

No patient demographics influenced the postoperative pathway at Day 90. Only extrinsic factors involving graft ischemia time, intraoperative transfusion, and intraoperative ECMO determined early postoperative pathway.

Substratum interactions determine immune response to allogeneic transplants of endothelial cells

Endothelial cells (ECs) are central to vascular health but also interact with and regulate the immune system. Changes in endothelial state enable immune cells to migrate into the tissue to facilitate repair and fight infection. ECs modulate the function of immune cells through the expression of adhesion molecules, chemokines, major histocompatibility complex (MHC), and an array of co-stimulatory and inhibitor molecules. These interactions allow ECs to act as antigen presenting cells (APCs) and influence the outcome of immune recognition. This study elucidates how EC microenvironment, vascular cell biology, and immune response are not only connected but interdependent. More specifically, we explored how cell-substratum interactions influence EC antigen presentation and co-stimulation, and how these differences affect allorecognition in animal models of cell transplantation. Investigation of EC state was carried out using RNA sequencing while assessment of the allogeneic response includes measurements of immune cell cytotoxic ability, T cell proliferation, cytokine release, serum antibodies, and histological staining. Differences in substratum led to divergent EC phenotypes which in turn influenced immune response to transplanted cells, both due to the physical barrier of matrix-adhesion and differences in expression of surface markers. ECs grown in 2D on tissue culture plastic or in 3D on collagen scaffolds had significantly different basal levels of MHC expression, co-stimulatory and adhesion molecules. When treated with cytokines to mimic an inflammatory state, ECs did not converge to a single phenotype but rather responded differently based on their substratum. Generally, 3D ECs were more responsive to inflammatory stimuli than 2D ECs. These unique expression patterns measured in vitro also influence immune recognition in vivo. ECs grown in 2D were more likely to provoke a cytotoxic response while 3D ECs induced T cell proliferation. ECs are uniquely configured to sense not only local flow and mechanical forces but a range of markers related to systemic state, including immune function. ECs interact with immune cells with differing results depending on the environment in which the EC-lymphocyte interaction occurs. Therefore, understanding this relationship is essential to predicting and modifying the outcome of EC-immune interacts. We specifically examined the relationship between EC substratum and allorecognition.

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.

Ex Vivo Lung Perfusion: A Review of Current and Future Application in Lung Transplantation

The number of waitlisted lung transplant candidates exceeds the availability of donor organs. Barriers to utilization of donor lungs include suboptimal lung allograft function, long ischemic times due to geographical distance between donor and recipient, and a wide array of other logistical and medical challenges. Ex vivo lung perfusion (EVLP) is a modality that allows donor lungs to be evaluated in a closed circuit outside of the body and extends lung donor assessment prior to final acceptance for transplantation. EVLP was first utilized successfully in 2001 in Lund, Sweden. Since its initial use, EVLP has facilitated hundreds of lung transplants that would not have otherwise happened. EVLP technology continues to evolve and improve, and currently there are multiple commercially available systems, and more under investigation worldwide. Although barriers to universal utilization of EVLP exist, the possibility for more widespread adaptation of this technology abounds. Not only does EVLP have diagnostic capabilities as an organ monitoring device but also the therapeutic potential to improve lung allograft quality when specific issues are encountered. Expanded treatment potential includes the use of immunomodulatory treatment to reduce primary graft dysfunction, as well as targeted antimicrobial therapy to treat infection. In this review, we will highlight the historical development, the current state of utilization/capability, and the future promise of this technology.

A Focused Review on Primary Graft Dysfunction after Clinical Lung Transplantation: A Multilevel Syndrome

Primary graft dysfunction (PGD) is the clinical syndrome of acute lung injury after lung transplantation (LTx). However, PGD is an umbrella term that encompasses the ongoing pathophysiological and -biological mechanisms occurring in the lung grafts. Therefore, we aim to provide a focused review on the clinical, physiological, radiological, histological and cellular level of PGD. PGD is graded based on hypoxemia and chest X-ray (CXR) infiltrates. High-grade PGD is associated with inferior outcome after LTx. Lung edema is the main characteristic of PGD and alters pulmonary compliance, gas exchange and circulation. A conventional CXR provides a rough estimate of lung edema, while a chest computed tomography (CT) results in a more in-depth analysis. Macroscopically, interstitial and alveolar edema can be distinguished below the visceral lung surface. On the histological level, PGD correlates to a pattern of diffuse alveolar damage (DAD). At the cellular level, ischemia-reperfusion injury (IRI) is the main trigger for the disruption of the endothelial-epithelial alveolar barrier and inflammatory cascade. The multilevel approach integrating all PGD-related aspects results in a better understanding of acute lung failure after LTx, providing novel insights for future therapies.

Donor selection for multiorgan transplantation

PURPOSE OF REVIEW

There is limited data and guidance on donor selection for multiorgan transplantation. In this article, we review the current Organ Procurement and Transplantation Network policy on multiorgan allocation and the ideal donor criteria for each specific organ, in order to provide a framework to guide donor selection for various scenarios of multiorgan transplantation, including heart-kidney, heart-lung, heart-liver and heart-kidney-liver transplant procedures.

RECENT FINDINGS

Combined heart-kidney transplantation is the most common multiorgan transplant procedure and requires the most stringent HLA matching to ensure optimal graft survival. Using the virtual crossmatch and desensitization therapies can shorten waitlist times without increasing posttransplant rejection or mortality rates. The ideal heart-lung donor tends to be younger than other multiorgan transplants, and more tolerant to HLA mismatch, but ideally requires donors with no prior history of smoking, a short period of time on mechanical ventilation, adequate oxygenation and absence of pulmonary infection. The ideal heart-liver donor is often driven by criteria specific to the donor heart. Finally, several observational studies suggest that livers are more tolerant to HLA mismatch than other organs, and offer some degree of immune protection in combined organ transplants.

SUMMARY

Multiorgan transplantation is a steadily growing field. The required short ischemic time for the donor heart is often the limiting factor, as well as the scarcity of appropriate donors available within geographical confines. In general, as with single organ transplantation, younger age, size matching, few medical comorbidities and HLA compatibility confer the best posttransplant outcomes.

Airway complications in lung transplantation

Airway complications (ACs) after lung transplantation remain an important source of morbidity and mortality despite significant advances in the surgical technics, leading to increased cost, and decrease quality of life. The incidences of ACs after lung transplantation range from 2% to 33%, even though most transplant centers have reported rates in the range of 7% to 8%. However, the reported rate of ACs has been inconsistent as a result of a lack of standardized airway definitions and grading protocols before the recent 2018 International Society for Heart and Lung Transplantation (ISHLT) proposed consensus guidelines on ACs after lung transplantation. The ACs include stenosis, perioperative and postoperative bronchial infections, bronchial necrosis and dehiscence, excess granulation tissue, and tracheobronchomalacia (TBM). Anastomosis infection, necrosis, or dehiscence typically develops within the first month after lung transplantation. The most frequent AC after lung transplantation is bronchial stenosis. Several risk factors have been proposed to the development of ACs after lung transplantation, including surgical anastomosis techniques, hypoperfusion, infections, donor and recipient factors, immunosuppression agents, and organ preservation. ACs might be prevented by early recognition of the airway pathology, using advance medical management, and interventional bronchoscopy procedures. Balloon bronchoplasty, cryotherapy, laser photo resection, electrocautery, high-dose endobronchial brachytherapy, and bronchial stents placement are the most frequent interventional bronchoscopic procedures utilized for the management of ACs.

Lung transplantation using allografts with more than 8 hours of ischemic time: A single-institution experience

BACKGROUND

Six hours was historically regarded as the limit of acceptable ischemic time for lung allografts. However, broader sharing of donor lungs often necessitates use of allografts with ischemic time >6 hours. We characterized the association between ischemic time ≥8 hours and outcomes after lung transplantation using a contemporary cohort from a high-volume institution.

METHODS

Patients who underwent primary isolated bilateral lung transplantation between 1/2016 and 5/2020 were included. Patients bridged to transplant with extracorporeal membrane oxygenation or mechanical ventilation, and ex-vivo perfusion cases were excluded. Recipients were stratified by total allograft ischemic time <8 hours (standard) vs ≥8 hours (long). Perioperative outcomes and post-transplant survival were compared between groups.

RESULTS

Of 358 patients, 95 (26.5%) received long ischemic time (≥8 hours) lungs. Long ischemic time recipients were more likely to be male and have donation after circulatory death donors than standard ischemic time recipients. On unadjusted analysis, long and standard ischemic time recipients had similar survival, and similar rates of grade 3 primary graft dysfunction at 72 hours, extracorporeal membrane oxygenation post-transplant, acute rejection within 30 days, reintubation, and post-transplant length of stay. After adjustment, long and standard ischemic time recipients had comparable risks of mortality or graft failure.

CONCLUSIONS

In a modern cohort, use of lung allografts with "long" ischemic time ≥8 hours were associated with acceptable perioperative outcomes and post-transplant survival. Further investigation is required to better understand how broader use impacts post-lung transplant outcomes and the implications for smarter sharing under an evolving national allocation policy.

Pilot Trial of Extended Hypothermic Lung Preservation to Analyze Ischemia-reperfusion Injury in Pigs

BACKGROUND

In lung transplantation (LT), the length of ischemia time is controversial as it was arbitrarily stablished. We ought to explore the impact of extended cold-ischemia time (CIT) on ischemia-reperfusion injury in an experimental model.

METHODS

Experimental, randomized pilot trial of parallel groups and final blind analysis using a swine model of LT. Donor animals (n=8) were submitted to organ procurement. Lungs were subjected to 6h (n=4) or 12h (n=4) aerobic hypothermic preservation. The left lung was transplanted and re-perfused for 4h. Lung biopsies were obtained at (i) the beginning of CIT, (ii) the end of CIT, (iii) 30min after reperfusion, and (iv) 4h after reperfusion. Lung-grafts were histologically assessed by microscopic lung injury score and wet-to-dry ratio. Inflammatory response was measured by determination of inflammatory cytokines. Caspase-3 activity was determined as apoptosis marker.

RESULTS

We observed no differences on lung injury score or wet-to-dry ratio any given time between lungs subjected to 6h-CIT or 12h-CIT. IL-1β and IL6 showed an upward trend during reperfusion in both groups. TNF-α was peaked within 30min of reperfusion. IFN-γ was hardly detected. Caspase-3 immunoexpression was graded semiquantitatively by the percentage of stained cells. Twenty percent of apoptotic cells were observed 30min after reperfusion.

CONCLUSIONS

We observed that 6 and 12h of CIT were equivalent in terms of microscopic lung injury, inflammatory profile and apoptosis in a LT swine model. The extent of lung injury measured by microscopic lung injury score, proinflammatory cytokines and caspase-3 determination was mild.

Pilot Trial of Extended Hypothermic Lung Preservation to Analyze Ischemia-reperfusion Injury in Pigs

BACKGROUND

In lung transplantation (LT), the length of ischemia time is controversial as it was arbitrarily stablished. We ought to explore the impact of extended cold-ischemia time (CIT) on ischemia-reperfusion injury in an experimental model.

METHODS

Experimental, randomized pilot trial of parallel groups and final blind analysis using a swine model of LT. Donor animals (n=8) were submitted to organ procurement. Lungs were subjected to 6h (n=4) or 12h (n=4) aerobic hypothermic preservation. The left lung was transplanted and re-perfused for 4h. Lung biopsies were obtained at (i) the beginning of CIT, (ii) the end of CIT, (iii) 30min after reperfusion, and (iv) 4h after reperfusion. Lung-grafts were histologically assessed by microscopic lung injury score and wet-to-dry ratio. Inflammatory response was measured by determination of inflammatory cytokines. Caspase-3 activity was determined as apoptosis marker.

RESULTS

We observed no differences on lung injury score or wet-to-dry ratio any given time between lungs subjected to 6h-CIT or 12h-CIT. IL-1β and IL6 showed an upward trend during reperfusion in both groups. TNF-α was peaked within 30min of reperfusion. IFN-γ was hardly detected. Caspase-3 immunoexpression was graded semiquantitatively by the percentage of stained cells. Twenty percent of apoptotic cells were observed 30min after reperfusion.

CONCLUSIONS

We observed that 6 and 12h of CIT were equivalent in terms of microscopic lung injury, inflammatory profile and apoptosis in a LT swine model. The extent of lung injury measured by microscopic lung injury score, proinflammatory cytokines and caspase-3 determination was mild.

Local versus distant lung donor procurement does not influence short-term clinical outcomes

OBJECTIVE

The purpose of this study was to recognize clinically meaningful differences in lung transplant outcomes based on local or distant lung procurement. This could identify if the lung allocation policy change would influence patient outcomes.

METHODS

This single-center retrospective cohort study analyzed adult patients who underwent lung transplant from 2006 to 2017. Donor and recipient data were abstracted from a collaborative, prospective registry shared by our local organ procurement organization, and tertiary medical center. Short-term outcomes, 1-year survival, and hospitalization costs were compared between local and distant lung transplants defined by donor service area.

RESULTS

Of the 722 lung transplants performed, 392 (54%) had local donors and 330 (46%) had distant donors. Donors were similar in age and cause of death. Recipients were significantly different in diagnosis and local recipients had lower median lung allocation scores (local, 37.3 and distant, 44.9; P < .01). Distant lung transplants had longer total ischemic times (local, 231 ± 52 minutes and distant, 313 ± 48 minutes; P < .01). The rate of major complications, length of hospital stay, and 1-year survival were similar between groups. Distant lung transplants were associated with higher median overall cost (local, $183,542 and distant, $229,871; P < .01). Local lung transplants were more likely to be performed during daytime (local, 333 out of 392 [85%] and distant, 291 out of 330 [61%]; P < .01).

CONCLUSIONS

Local lung transplants are associated with shorter ischemic times, lower cost, and greater likelihood of daytime surgery. Short- and intermediate-term outcomes are similar for lung transplants from local and distant donors. The new lung allocation policy, with higher proportion of distant lung transplants, is likely to incur greater costs but provide similar outcomes.

Impact of Cold Ischemia Time on Frequency of Airway Complications Among Lung Transplant Recipients

BACKGROUND

The cold ischemia time (CIT) is a period of time between harvesting an organ for transplant and its reperfusion just after implantation. CIT may have an impact on frequency of complications after lung transplant that can be treated by means of bronchoscopic intervention. The aim of the study was to investigate the correlation between CIT and frequency of bronchoscopic intervention.

METHODS

The retrospective study consists of 91 patients: 22 single lung recipients (24%) and 69 double lung recipients (76%) who underwent lung transplant from March 2012 to June 2019. All statistical analyses were performed in SPSS 25.0 and R 3.5.3. The P levels less than .05 were deemed statistically significant.

RESULTS

The average CIT in single lung transplant was 5.91 hours, and in double lung transplant it was 8.61 hours. For the 4- to 8-hour CIT the percentages were 80.95% for single lung recipients and 46.38% for double lung recipients. For CIT longer than 8 hours, the following percentages were observed: 9.53% in single lung transplant and 53.62% in double lung transplant. Each subsequent hour of CIT exponentially increases the risk of intervention 1505 times (50.05%).

CONCLUSIONS

Prolonged CIT seems to be a risk factor for airway complication, especially in the double lung recipient group.

Current techniques and the future of lung preservation

Although lung transplant remains the only option for patients suffering from end-stage lung failure, donor supply is insufficient to meet demand. Static cold preservation is the most common method to preserve lungs in transport to the recipient; however, this method does not improve lung quality and only allows for 8 h of storage. This results in lungs which become available for donation but cannot be used due to failure to meet physiologic criteria or an inability to store them for a sufficient time to find a suitable recipient. Therefore, lungs lost due to failure to meet physiological or compatibility criteria may be mitigated through preservation methods which improve lung function and storage durations. Ex situ lung perfusion (ESLP) is a recently developed method which allows for longer storage times and has been demonstrated to improve lung function such that rejected lungs can be accepted for donation. Although greater use of ESLP will help to improve donor lung utilization, the ability to cryopreserve lungs would allow for organ banking to better utilize donor lungs. However, lung cryopreservation research remains underrepresented in the literature despite its unique advantages for cryopreservation over other organs. Therefore, this review will discuss the current techniques for lung preservation, static cold preservation and ESLP, and provide a review of the cryopreservation challenges and advantages unique to lungs.

Successful Implementation of Unmanned Aircraft Use for Delivery of a Human Organ for Transplantation

OBJECTIVE

To understand and overcome the challenges associated with moving life-urgent payloads using unmanned aircraft.

BACKGROUND DATA

Organ transportation has not been substantially innovated in the last 60 years. Unmanned aircraft systems (UAS; ie, drones) have the potential to reduce system inefficiencies and improve access to transplantation. We sought to determine if UASs could successfully be integrated into the current system of organ delivery.

METHODS

A multi-disciplinary team was convened to design and build an unmanned aircraft to autonomously carry a human organ. A kidney transplant recipient was enrolled to receive a drone-shipped kidney.

RESULTS

A uniquely designed organ drone was built. The aircraft was flown 44 times (total of 7.38 hours). Three experimental missions were then flown in Baltimore City over 2.8 miles. For mission #1, no payload was carried. In mission #2, a payload of ice, saline, and blood tubes (3.8 kg, 8.4 lbs) was flown. In mission #3, a human kidney for transplant (4.4 kg, 9.7 lbs) was successfully flown by a UAS. The organ was transplanted into a 44-year-old female with a history of hypertensive nephrosclerosis and anuria on dialysis for 8 years. Between postoperative days (POD) 1 and 4, urine increased from 1.0 L to 3.6 L. Creatinine decreased starting on POD 3, to an inpatient nadir of 6.9 mg/dL. The patient was discharged on POD 4.

CONCLUSIONS

Here, we completed the first successful delivery of a human organ using unmanned aircraft. This study brought together multidisciplinary resources to develop, build, and test the first organ drone system, through which we performed the first transplant of a drone transported kidney. These innovations could inform not just transplantation, but other areas of medicine requiring life-saving payload delivery as well.

ISHLT Consensus Statement on adult and pediatric airway complications after lung transplantation: Definitions, grading system, and therapeutics

Airway complications remain a major cause of morbidity and mortality after cardiothoracic transplantation. The reported incidence of airway ischemic complications varies widely, contributed to by the lack of a universally accepted grading system and standardized definitions. Furthermore, the majority of the existing classification systems fail to integrate the wide range of possible bronchial complications that may develop after lung transplant. Hence, a Working Group was created by the International Society for Heart and Lung Transplantation with the aim of elaborating a universal definition of adult and pediatric airway complications and grading system. One such area of focus is to understand the problem in the context of a more standardized consensus of classifying airway ischemia. This consensus definition will have major clinical, therapeutics, and research implications.

Lung Transplant Center Volume Ameliorates Adverse Influence of Prolonged Ischemic Time on Mortality

The influence of prolonged ischemic time on outcomes after lung transplant is controversial, but no research has investigated ischemic time in the context of center volume. We used data from the United Network for Organ Sharing to estimate the influence of ischemic time on patient survival conditional on center volume in the post-lung allocation score era (2005-2015). The analytic sample included 14 877 adult lung transplant recipients, of whom 12 447 were included in multivariable survival analysis. Patient survival was improved in high-volume centers compared with low-volume centers (log-rank test p = 0.001), although mean ischemic times were longer at high-volume centers (5.16 ± 1.70 h vs. 4.83 ± 1.63 h, p < 0.001). Multivariable Cox proportional hazards regression stratified by transplant center found an adverse influence of longer ischemic time at low-volume centers but not at high-volume centers. At centers performing 50 transplants in the period 2005-2015, for example, 8 versus 6 h of ischemia were associated with an 18.9% (95% confidence interval 6.5-32.7%; p < 0.001) greater mortality hazard, whereas at centers performing 350 transplants in this period, no differences in survival by ischemic time were predicted. Despite longer mean ischemic time at high-volume transplant centers, these centers had favorable patient outcomes and no adverse survival implications of prolonged ischemia.

Risk factors and outcome of primary graft dysfunction after lung transplantation in Korea

BACKGROUND

Primary graft dysfunction (PGD) is a severe, acute and post-transplantation lung injury associated with early morbidity and mortality. We aimed to identify clinical risk factors for PGD, as well as the outcome of PGD after lung transplantation in Korea.

METHODS

We retrospectively analyzed lung transplant patients in a South Korean Hospital. The primary outcome was grade 3 PGD, defined according to the International Society for Heart and Lung Transplantation criteria. We compared grade 0-2 PGD group to grade 3 PGD group to identify the risk factors and outcome of grade 3 PGD.

RESULTS

Sixty-one patients were enrolled; 16 (26.2%) developed grade 3 PGD. Univariate analysis revealed higher body mass index (BMI) and history of smoking, extracorporeal membrane oxygenation (ECMO) before transplantation in recipients, and an extended intraoperative ischemic time as risk factors for grade 3 PGD. In multivariate analysis, independent risk factors for PGD were higher BMI in recipients [odds ratio (OR), 1.286; P=0.043] and total intraoperative ischemic time (OR, 1.028; P=0.007). As compared to grade 0-2 PGD, grade 3 PGD was significantly associated with a higher re-operation rate (grade 0-2 PGD vs. grade 3 PGD, 22.2% vs. 50.0%; P=0.036), prolonged ventilator apply (median: 6.0 vs. 14.5 days; P=0.044), a longer intensive care unit stay (median: 9.0 vs. 17.0 days; P=0.041), and a higher rate of renal replacement therapy (RRT) (17.8% vs. 62.5%; P=0.002) after transplantation.

CONCLUSIONS

Patients who developed grade 3 PGD had higher re-operation rate, longer ventilator apply, longer intensive care unit stay, higher rate of RRT, with higher BMI and total intraoperative ischemic time being the significant risk factor. These findings may allow physicians to modify risk factors before development of PGD.

Influence of graft ischemic time on survival in children with cystic fibrosis after lung transplantation

BACKGROUND

The influence of graft ischemic time on survival after lung transplantation (LTx) in children with cystic fibrosis (CF) is not well studied.

METHODS

The United Network for Organ Sharing (UNOS) database was queried from May 2005 to September 2013 to examine the impact of ischemic time of <4, 4-6, and >6 hr in pediatric LTx recipients with CF.

RESULTS

One hundred and ninety-nine patients with CF under 18 years of age that were first-time LTx recipients from cadaveric donors were included in the analysis. Compared to 4-6 hr, univariate analysis showed a significant increase in mortality hazard with an ischemic time of <4 hr (HR = 2.407; 95%CI: 1.292, 4.485; P = 0.006) but not >6 hr (HR = 1.350; 95%CI: 0.796, 2.290; P = 0.266). A Kaplan-Meier plot demonstrated the highest survival with 4-6 hr (Log-rank test P = 0.018) of ischemic time. Multivariate Cox model confirmed a significantly higher mortality risk with <4 hr (HR = 2.388; 95%CI: 1.169, 4.764; P = 0.014) and not >6 hr (HR = 1.407; 95%CI: 0.760, 2.605; P = 0.278) in relation to 4-6 hr. Sub-analysis examining ischemic time and the hazard of bronchiolitis obliterans syndrome with death as a competing risk found no significant differences in the hazard of this outcome across the three ischemic time categories.

CONCLUSIONS

Ischemic time of 4-6 hr was associated with the highest long-term survival in first-time pediatric LTx recipients with CF, with ischemic time <4 hr related to diminished survival. Pediatr Pulmonol. 2016; 51:908-913. © 2016 Wiley Periodicals, Inc.

Hospital length of stay after lung transplantation: Independent predictors and association with early and late survival

BACKGROUND

Duration of index hospitalization after lung transplantation (LTx) is an important variable that has not received much attention. We sought to determine independent predictors of prolonged hospital length of stay (LOS) and its association with early and late outcomes.

METHODS

The United Network of Organ Sharing database was queried for adult patients undergoing LTx between 2006 and 2014 (N = 14,320). Patients with dual organ or previous transplantation and patients who died during the first 25 days after LTx were excluded (n = 12,647, mean age 55.2 years ± 13.1). Primary outcome was prolonged LOS (>25 days) (3,251/12,647; 25.7%). Donor, recipient, and procedure-related variables were analyzed as potential predictors of prolonged LOS. Association of prolonged LOS with 1-year and 5-year survival was evaluated using Cox proportional hazards analysis.

RESULTS

Independent predictors of prolonged LOS included serum albumin, lung allocation score, functional status, and need of extracorporeal membrane oxygenation or ventilator support at the time of transplant; donor age >40 years; gender mismatch (female donor to male recipient); donor body mass index; African American ethnicity; ischemic time >6 hours; and double LTx. Prolonged LOS was independently associated with increased mortality at 1 year (hazard ratio, 3.96; 95% confidence interval, 3.48-4.50; p < 0.001) and 5 years (hazard ratio, 2.00; 95% confidence interval, 1.79-2.25; p < 0.001).

CONCLUSIONS

A significant proportion of patients have a prolonged LOS after LTx, and several recipient, donor, and procedure-related variables are independent predictors of this outcome. Patients with prolonged LOS after LTx have significantly increased risk of death at 1 year and 5 years.

Lung donor selection criteria

The criteria that define acceptable physiologic and social parameters for lung donation have remained constant since their empiric determination in the 1980s. These criteria include a donor age between 25-40, a arterial partial pressure of oxygen (PaO2)/FiO2 ratio greater than 350, no smoking history, a clear chest X-ray, clean bronchoscopy, and a minimal ischemic time. Due to the paucity of organ donors, and the increasing number of patients requiring lung transplant, finding a donor that meets all of these criteria is quite rare. As such, many transplants have been performed where the donor does not meet these stringent criteria. Over the last decade, numerous reports have been published examining the effects of individual acceptance criteria on lung transplant survival and graft function. These studies suggest that there is little impact of the historical criteria on either short or long term outcomes. For age, donors should be within 18 to 64 years old. Gender may relay benefit to all female recipients especially in male to female transplants, although results are mixed in these studies. Race matched donor/recipients have improved outcomes and African American donors convey worse prognosis. Smoking donors may decrease recipient survival post transplant, but provide a life saving opportunity for recipients that may otherwise remain on the transplant waiting list. No specific gram stain or bronchoscopic findings are reflected in recipient outcomes. Chest radiographs are a poor indicator of lung donor function and should not adversely affect organ usage aside for concerns over malignancy. Ischemic time greater than six hours has no documented adverse effects on recipient mortality and should not limit donor retrieval distances. Brain dead donors and deceased donors have equivalent prognosis. Initial PaO2/FiO2 ratios less than 300 should not dissuade donor organ usage, although recruitment techniques should be implemented with intent to transplant.

Lung transplantation for patients with high lung allocation score: single-center experience

BACKGROUND

The lung allocation score (LAS) assigns organ allocation priority based on medical urgency and the likelihood of posttransplant survival. This study is a review of a single institutional experience for lung transplantation in the era of LAS.

METHODS

We performed a retrospective review of 527 consecutive patients, from May 2005 to February 2010, who underwent lung transplant at our institution, comprising a high LAS group (LAS≥50, n=108) and a low LAS group (LAS<50, n=419). Kaplan-Meier and univariate analyses were performed to assess postoperative mortality as a primary outcome, and length of ventilator support and intensive care unit stay as secondary outcomes. Risk factors, including demographics, pulmonary status, and surgical and donor variables, were compared. Predictors of mortality were determined using a Cox proportional hazard model.

RESULTS

Survivals after 30 days, 90 days, 1 year, and 3 years were 92.6%, 87.8%, 71.5%, and 52.0%, respectively, in the high LAS group, and 96.9%, 93.5%, 83.2%, and 73.9% in the low LAS group (p<0.001). The incidence of prolonged ventilator support and the need for tracheostomy were higher, and intensive care unit stay was longer in the high LAS group. In the high LAS group, ischemic time greater than 8 hours was an independent predictor for mortality (hazard ratio: 3.080; 95% confidence interval 1.101 to 8.161, p=0.032).

CONCLUSIONS

Lung transplant in patients with high a LAS is associated with significantly decreased survival and increased complications compared with patients with a low LAS. Ischemic time greater than 8 hours is a significant predictor of death in patients with a high LAS.

Geographic distance between donor and recipient does not influence outcomes after lung transplantation

BACKGROUND

The shortage in organ donation is a major limiting factor for patients with end-stage lung disease. Expanding the donor pool would be beneficial. We investigated the importance of geographic distance between the donor and recipient and hypothesized that it would not be a critical determinant of outcomes after lung transplantation.

METHODS

We retrospectively reviewed the United Network for Organ Sharing lung transplant database from 2000 to 2005 to allow sufficient time for bronchiolitis obliterans syndrome (BOS) development. Allograft recipients were stratified by geographic distance from their donors (local, regional, and national) and had yearly follow-up. The primary end points were the development of BOS and 1-year and 3-year mortality. Posttransplant outcomes were compared using a multivariable Cox proportional hazard model. Kaplan-Meier curves were compared by log-rank test.

RESULTS

Of 6,055 allograft recipients, donors were local in 59%, regional in 19.3%, and national in 21.7%. BOS-free survival did not differ by geographic distance. Geographic distance did not independently predict BOS (hazard ratio, 1.03; 95% confidence interval, 0.96 to 1.10). Similarly, Kaplan-Meier survival curves were not significantly worse for recipients with national donors. Geographic distance did not independently predict 3-year mortality (hazard ratio, 0.95; 95% confidence interval, 0.89 to 1.01).

CONCLUSIONS

With appropriate donor selection, moderately long geographic distance (average ischemic time < 6 hours) between the donor and recipient is not associated with the development of BOS or increased death after lung transplantation. By placing less emphasis on distance, more donors could potentially be used to expand the donor pool.

Single-lung transplantation in the setting of aborted bilateral lung transplantation

Background. The outcome of patients undergoing a single-lung transplant in the setting of an aborted bilateral lung transplant is unclear. Methods. A retrospective review of single lung transplants at an institutional program. Results. Of the 543 lung transplants performed over the last 10 years, 31 (5.7%) were single-lung transplants. Nineteen of 31 (61%) were planned single-lung transplants, while 12/31 (39%) were intraoperatively aborted, double lung transplants converted to single-lung transplants. The aborted and planned groups were similar in age, lung allocation score and NYHA status. The reasons for aborted double lung transplantation were cardiac/hemodynamic instability 4/12 (33%), difficult pneumonectomy 3/12 (25%), size mismatch 4/12(33%), and technical issues 1/12 (8%). The aborted group had higher CPB utilization (5/12 versus 1/19, P = .02), similar ischemic times (260 versus 234 min) and similar incidence of grade 3 primary graft dysfunction (6/12 versus 3/19, P = .13). ECMO was required for graft dysfunction in 2 patients in the aborted group. The one and two-year survival was 84% and 79% in the planned group and 62% and 52% in the aborted group, respectively. Conclusions. Patients undergoing single-lung transplantation in the setting of an aborted bilateral lung transplant may be at a higher risk of worse outcomes.

Early effects of the ex vivo evaluation system on graft function after swine lung transplantation

OBJECTIVES

Ex vivo lung evaluation (ex vivo) has been developed as a useful method by which to assess lungs from donation-after-cardiac death (DCD) donors prior to transplant. However, the safety of the ex vivo circulation itself with respect to grafts has not been fully investigated. The aim of this study is to evaluate the effects of the ex vivo circuit using a swine lung transplant model.

METHODS

Lungs with or without 2-h warm ischemia were used. To assess post-transplant graft function, the left lung was transplanted after 2-h ex vivo or cold preservation; blood gas analysis of the left pulmonary vein (partial pressure of oxygen, PO(2)) was performed during the 6-h post-transplant follow-up period. Data were compared between the ex vivo (+) and ex vivo (-) groups.

RESULTS

Partial pressure of oxygen/ inspired oxygen fraction (PO(2)/FiO(2)) in the ex vivo (-) group was significantly greater than that in the ex vivo (+) group until 3h after transplant. The PO(2)/FiO(2) levels in both groups then increased and became similar at 6 h after transplant, regardless of whether ischemic or non-ischemic lungs (p<0.001 and p=0.004, respectively) were used.

CONCLUSIONS

Negative effects of the ex vivo system were limited and seen only in the immediate post-transplant period. Therefore, in DCD swine lung transplantation, the ex vivo system appears to be safe.

Bronchiolitis obliterans syndrome occurs earlier in the post-lung allocation score era

OBJECTIVES

In 2005, the time-based waiting list for lung transplantation was replaced by an illness/benefit lung allocation score (LAS). Although short-term outcomes after transplantation have been reported to be similar before and after the new system, little is known about long-term results. The objective of this study was to evaluate the impact of LAS on the development of bronchiolitis obliterans syndrome as well as on overall 3-year and bronchiolitis obliterans syndrome-related survival.

METHODS

Data obtained from the United Network for Organ Sharing were used to review 8091 patients who underwent lung transplantation from 2002 to 2008. Patients were stratified according to time of transplantation into those treated before initiation of the LAS (pre-LAS group, January 2002-April 2005, n = 3729) and those treated after implementation of the score (post-LAS group, May 2005-May 2008, n = 4362). Overall, 3-year survivals for patient groups were compared using a univariate analysis, Cox proportional hazards model to generate a relative risk, and Kaplan-Meier curve analyses.

RESULTS

During the 3-year follow-up period, bronchiolitis obliterans syndrome developed in 22% of lung transplant recipients (n = 1801). Although the incidence of postoperative bronchiolitis obliterans syndrome development was similar between groups, post-LAS patients incurred fewer bronchiolitis obliterans syndrome-free days (609 ± 7.5 vs 682 ± 9; P <.0001; log-rank test P = .0108) than did pre-LAS patients. Overall 3-year survival was lower in post-LAS patients and approached statistical significance (P = .05). Similarly, bronchiolitis obliterans syndrome-related survival was worse for patients in the post-LAS group (log-rank test P = .01).

CONCLUSIONS

In the current LAS era, lung transplant recipients have significantly fewer bronchiolitis obliterans syndrome-free days after 3-year follow-up. Compared with the pre-LAS population, overall and bronchiolitis obliterans syndrome-related survival appears worse in the post-LAS era. Limitation of known risk factors for development of bronchiolitis obliterans syndrome-may prove even more important in this patient population.

Overview of lung transplantation

Although significant gains have been made in improving lung function and survival in cystic fibrosis (CF), ultimately respiratory failure is the leading cause of mortality in these patients. For CF patients with end stage lung disease, lung transplantation is an option for treatment. The field of lung transplantation has progressed markedly in the last 20 years. Nonetheless it remains a technically complex and challenging procedure, and patients are at risk for numerous short term and long term complications. Potential transplant recipients must be physically and psychologically prepared for the arduous process involved in lung transplantation. This article will review the history of lung transplantation, indications for transplantation, surgical techniques, and complications of transplantation.

Elevated levels of the receptor for advanced glycation end products, a marker of alveolar epithelial type I cell injury, predict impaired alveolar fluid clearance in isolated perfused human lungs

BACKGROUND

Although alveolar epithelial injury is a major determinant of outcome in patients with acute lung injury, there is no reliable biological marker of alveolar epithelial injury. The primary objective was to determine whether elevated levels of the receptor for advanced glycation end products (RAGE), a marker of alveolar epithelial injury, reflect impaired alveolar fluid clearance (AFC) in an ex vivo perfused human lung preparation. A second objective was to determine whether levels of a marker of endothelial injury, von Willebrand factor antigen (vWF:Ag), are associated with impaired AFC.

METHODS

Human lungs (N = 30) declined for transplantation by the California Transplant Donor Network were perfused at a constant pulmonary artery pressure of 12 mm Hg. Following rewarming to 36 degrees C, the lungs were inflated with a continuous positive airway pressure of 10 cm H(2)O. RAGE and vWF:Ag levels and AFC rates were then measured.

RESULTS

The rate of AFC was inversely correlated with RAGE levels in the alveolar fluid (p < 0.005). Similarly, the concentration of RAGE in the alveolar fluid was significantly higher in lungs with submaximal AFC, defined in a prespecified analysis as <or= 14%/h, when compared with lungs with preserved AFC (median 0.82 vs 0.43 microg/mL; p < 0.05). In contrast, vWF:Ag levels did not correlate with the rate of AFC.

CONCLUSIONS

RAGE may be a useful biological marker of alveolar epithelial injury and impaired AFC in donor lungs prior to transplant and perhaps in patients with acute lung injury.

Interstitial inflammatory lesions of the pulmonary allograft: a retrospective analysis of 2697 transbronchial biopsies

BACKGROUND

Parenchymal and bronchial inflammatory and fibrotic lesions other than acute cellular rejection (ACR) and lymphocytic bronchiolitis are prevalent; however, the context in which they appear is unknown, and often no specific treatment is instigated.

OBJECTIVES

To describe the prevalence, incidence and possible associations between commonly identified inflammatory and fibrotic lesions in the pulmonary allograft.

METHODS

Retrospective chart review of all transbronchial biopsies performed within the first 2 years of 299 lung-transplanted patients in the period 1996 to 2006.

RESULTS

A total of 2697 biopsies were evaluated corresponding to a mean of 6+/-2 (median 8) completed schedules per patient. Diffuse alveolar damage (DAD) was the second most common histological finding within the first 2 weeks after transplantation. The peak prevalence of bronchiolitis obliterans organizing pneumonia (BOOP) and interstitial pneumonitis occurred at 4 to 6 weeks, and 6 to 12 weeks, respectively. There was a steady increase in the cumulative proportion of patients with fibrosis and bronchiolitis obliterans, at each successive scheduled surveillance time point beyond 3 months posttransplantation. The strongest histological correlations were between ACR and lymphocytic bronchiolitis (OR 5.1, P<0.0001) or interstitial fibrosis (OR 3.2, P<0.0001). Patients with interstitial pneumonitis and pulmonary hemosiderosis were also more likely to demonstrate the finding of interstitial fibrosis (OR 3.0 and 3.7, P<0.0001, respectively). Acute cellular rejection was not associated with DAD, and patients with lymphocytic bronchiolitis were not more likely to demonstrate features of organizing pneumonia (DAD or BOOP).

CONCLUSIONS

Histologic findings of ACR, lymphocytic bronchiolitis, BOOP, and interstitial pneumonitis were directly associated with the development of interstitial fibrosis and bronchiolitis obliterans.