Report of the ISHLT Working Group on Primary Lung Graft Dysfunction part III: donor-related risk factors and markers

Development and validation of a nomogram model to predict primary graft dysfunction in patients after lung transplantation based on the clinical factors

BACKGROUND

Primary graft dysfunction (PGD), a significant complication that can affect patients' prognosis and quality of life, develops within 72 h post lung transplantation (LTx). Early detection and prevention of PGD should be given special consideration. The purpose of this study was to create a clinical prediction model to forecast the occurrence of PGD.

METHODS

We collected information on 622 LTx patients from Wuxi People's Hospital from 2016 to 2020 and used the data to construct the prediction model. Information on 224 patients from 2021 to June 2022 was used for external validation. We used LASSO regression for variable screening. A nomogram was developed for model presentation. Distinctness, fit, and calibration were used to evaluate the performance of the model.

RESULTS

Subjects with respiratory failure, who received fresh frozen plasma, donor age, donor gender, donor mechanism of death, donor smoking, donor ventilator use time, and donor PaO 2/FiO 2 ratio were independent predictor variables for the occurrence of PGD. The area under the curve of the nomogram was .779. The Hosmer-Lemeshow test showed a good model fit (P = .158). The calibration curve of the nomogram is fairly close to the ideal diagonal. Moreover, the decision curve analysis revealed a positive net benefit of the model. External validation also confirmed the reliability of the model.

CONCLUSIONS

The nomogram of PGD based on clinical risk factors in postoperative LTx patients was established with high reliability. It provides clinicians and nurses with a new and effective tool for early prediction of PGD and early intervention.

Evaluation of Donor Lungs for Transplantation: The Efficacy of Screening Bronchoscopy for Detecting Donor Aspiration and Its Relationship to the Resulting Allograft Function in Corresponding Recipients

BACKGROUND

Potential organ donors often have suffered anoxic and/or traumatic brain injury during which they may have experienced aspiration of gastric material (AGM). Evaluation of such donors typically includes a screening bronchoscopic examination during which determinations of aspiration are made. The efficacy of this visual screening and its relationship to post-transplant allograft function are unknown.

METHODS

Before procurement, bronchoscopy was performed on donors in which both bronchoalveolar lavage fluid (BALF) was collected and a visual inspection made. As a marker of AGM, BALF specimens were analyzed for the presence of bile salts. Data collected on the corresponding recipients included primary graft dysfunction (PGD) score, post-transplant spirometry, acute rejection scores (ARS), and overall survival.

RESULTS

Of 31 donors evaluated, bronchoscopies revealed only 2 with visual evidence of AGM, whereas BALF analysis for bile salts indicated AGM in 14. As such, screening bronchoscopy had a sensitivity of only 7.1%. Visual detection of AGM via bronchoscopy was not associated with any resulting grade of PGD (χ2 = 2.96, P = .23); however, AGM defined by detection of bile salts was associated (χ2 = 7.56, P = .02). Over the first post-transplant year, the corresponding recipients experienced a similar improvement in allograft function (χ2 = 1.63, P = .69), ARS (P = .69), and survival (P = .24).

CONCLUSION

Visual inspection during a single bronchoscopic examination of lung donors underestimates the prevalence of AGM. The detection of bile salts in donor BALF is associated with early allograft dysfunction in the corresponding recipients but not with later allograft proficiency, acute rejection responses, or 1-year post-transplant survival.

Lung preservation: from perfusion to temperature

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Critical Care Management of the Lung Transplant Recipient

Lung transplantation is often the only treatment option for patients with severe irreversible lung disease. Improvements in donor and recipient selection, organ allocation, surgical techniques, and immunosuppression have all contributed to better survival outcomes after lung transplantation. Nonetheless, lung transplant recipients still experience frequent complications, often necessitating treatment in an intensive care setting. In addition, the use of extracorporeal life support as a means of bridging critically ill patients to lung transplantation has become more widespread. This review focuses on the critical care aspects of lung transplantation, both before and after surgery.

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.

Correlation between Neutrophil Extracellular Traps (NETs) Expression and Primary Graft Dysfunction Following Human Lung Transplantation

Primary graft dysfunction (PGD) is characterized by alveolar epithelial and vascular endothelial damage and inflammation, lung edema and hypoxemia. Up to one-third of recipients develop the most severe form of PGD (Grade 3; PGD3). Animal studies suggest that neutrophils contribute to the inflammatory process through neutrophil extracellular traps (NETs) release (NETosis). NETs are composed of DNA filaments decorated with granular proteins contributing to vascular occlusion associated with PGD. The main objective was to correlate NETosis in PGD3 (n = 9) versus non-PGD3 (n = 27) recipients in an exploratory study. Clinical data and blood samples were collected from donors and recipients pre-, intra- and postoperatively (up to 72 h). Inflammatory inducers of NETs' release (IL-8, IL-6 and C-reactive protein [CRP]) and components (myeloperoxidase [MPO], MPO-DNA complexes and cell-free DNA [cfDNA]) were quantified by ELISA. When available, histology, immunohistochemistry and immunofluorescence techniques were performed on lung biopsies from donor grafts collected during the surgery to evaluate the presence of activated neutrophils and NETs. Lung biopsies from donor grafts collected during transplantation presented various degrees of vascular occlusion including neutrophils undergoing NETosis. Additionally, in recipients intra- and postoperatively, circulating inflammatory (IL-6, IL-8) and NETosis biomarkers (MPO-DNA, MPO, cfDNA) were up to 4-fold higher in PGD3 recipients compared to non-PGD3 (p = 0.041 to 0.001). In summary, perioperative elevation of NETosis biomarkers is associated with PGD3 following human lung transplantation and these biomarkers might serve to identify recipients at risk of PGD3 and initiate preventive therapies.

Ex Vivo Lung Perfusion in Lung Transplantation

Ex vivo lung perfusion (EVLP) is a technique that enables active metabolism of the lung by creating an environment similar to that inside the body, even though the explanted lungs are outside the body. The EVLP system enables the use of lung grafts that do not satisfy the acceptance criteria for lung transplantation (LTx) by making it possible to evaluate the function of the lung grafts and repair lungs in poor condition, thereby reducing the waiting time of patients requiring LTx and consequently mortality.

CD11b suppresses TLR activation of nonclassical monocytes to reduce primary graft dysfunction after lung transplantation

Primary graft dysfunction (PGD) is the leading cause of postoperative mortality in lung transplant recipients and the most important risk factor for development of chronic lung allograft dysfunction. The mechanistic basis for the variability in the incidence and severity of PGD between lung transplant recipients is not known. Using a murine orthotopic vascularized lung transplant model, we found that redundant activation of Toll-like receptors 2 and 4 (TLR2 and -4) on nonclassical monocytes activates MyD88, inducing the release of the neutrophil attractant chemokine CXCL2. Deletion of Itgam (encodes CD11b) in nonclassical monocytes enhanced their production of CXCL2 and worsened PGD, while a CD11b agonist, leukadherin-1, administered only to the donor lung prior to lung transplantation, abrogated CXCL2 production and PGD. The damage-associated molecular pattern molecule HMGB1 was increased in peripheral blood samples from patients undergoing lung transplantation after reperfusion and induced CXCL2 production in nonclassical monocytes via TLR4/MyD88. An inhibitor of HMGB1 administered to the donor and recipient prior to lung transplantation attenuated PGD. Our findings suggest that CD11b acts as a molecular brake to prevent neutrophil recruitment by nonclassical monocytes following lung transplantation, revealing an attractive therapeutic target in the donor lung to prevent PGD in lung transplant recipients.

Bronchial Culture Growth From the Donor and Recipient as Predictive Factors in the Detection of Primary Graft Dysfunction and Pneumonia After Lung Transplant

OBJECTIVES

In this study, our aim was to investigate whether bacterial culture growth from donors and recipients is related to early posttransplant complications and to analyze its role in primary graft dysfunction and posttransplant pneumonia in lung transplant recipients.

MATERIALS AND METHODS

This retrospective cohort study included patients diagnosed with end-stage lung disease who received a lung transplant for treatment. We examined relationships between donor bronchial lavage, pretransplant recipient sputum, and recipient posttransplant serial bronchial lavage culture results, as well as the development of both primary graft dysfunction and pneumonia after lung transplant during the early posttransplant period.

RESULTS

Our study included 77 patients with median age of 48 years (25%-75% IQR, 34-56 years) and who were mostly men (79.2%; n = 61). Donor culture positivity was 62.3% (n = 48), and the positivity of sputum culture from patients before transplant was 20.8% (n = 16). Compared with that shown in those without versus those with primary graft dysfunction, there were significantly more positive sputum cultures from patients before transplant (P = .003). Recipients with donor culture growth had a longer duration of invasive mechanical ventilation (median of 4 days [IQR, 2-13 days] vs 1 day [IQR, 1-2 days]; P = .001, respectively) than those without. Multivariate logistic analysis identified both donor culture positivity (odds ratio: 3.391; 95% CI, 1.12-20.46; P = .0028) and sputum culture positivity in pretransplant recipient candidates (odds ratio: 6.494; 95% CI, 1.80-36.27; P = .004) as independent predictors of primary graft dysfunction.

CONCLUSIONS

Bacterial growth shown in donor bronchial lavage and sputum culture positivity in patients before transplant were found to be independent predictors of primary graft dysfunction in the early posttransplant period. Organism growth in both the donor and the recipient during the pretransplant period are important determinants for the development of primary graft dysfunction.

Early Postoperative Management of Lung Transplant Recipients

The early postoperative period after lung transplantation is a critical time. Prompt recognition and treatment of primary graft dysfunction can alter long-term allograft function. Cardiovascular, gastrointestinal, renal, and hematologic derangements are common and require close management to limit their negative sequelae.

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.

Advanced technologies for the preservation of mammalian biospecimens

The three classical core technologies for the preservation of live mammalian biospecimens-slow freezing, vitrification and hypothermic storage-limit the biomedical applications of biospecimens. In this Review, we summarize the principles and procedures of these three technologies, highlight how their limitations are being addressed via the combination of microfabrication and nanofabrication, materials science and thermal-fluid engineering and discuss the remaining challenges.

Blood transfusion of the donor is associated with stage 3 primary graft dysfunction after lung transplantation

BACKGROUND

The first aim of this study was to assess the association between stage 3 PGD and pre-donation blood transfusion of the donor. The secondary objectives were to assess the epidemiology of donor transfusion and the outcome of LT recipients according to donor transfusion status and massive donor transfusion status.

METHODS

This was an observational, prospective, single-center study. The results are expressed as absolute numbers, percentages, medians, and interquartile ranges. Statistical analyses were performed using Chi squared, Fischer's exact tests, and Mann-Whitney U tests (P < .05 was considered significant). A multivariate analysis was performed.

RESULTS

Between January 2016 and February 2019, 147 patients were included in the analysis. PGD was observed in 79 (54%) patients, 45 (31%) of whom had stage 3 PGD. Pre-donation blood transfusion was administered in 48 (33%) donors (median of 3[1-9] packed red cells (PRCs)). On multivariate analysis, stage 3 PGD was significantly associated with donor blood transfusion (OR 2.69, IC (1.14-6.38), P = .024). Mortality at days 28 and 90 was not significantly different according to the pre-donation transfusion status of the donor.

CONCLUSION

Pre-donation blood transfusion is associated with stage 3 PGD occurrence after LT. Transfusion data of the donor should be included in donor lung assessment.

Lung Transplantation, Pulmonary Endothelial Inflammation, and Ex-Situ Lung Perfusion: A Review

Lung transplantation (LTx) is the gold standard treatment for end-stage lung disease; however, waitlist mortality remains high due to a shortage of suitable donor lungs. Organ quality can be compromised by lung ischemic reperfusion injury (LIRI). LIRI causes pulmonary endothelial inflammation and may lead to primary graft dysfunction (PGD). PGD is a significant cause of morbidity and mortality post-LTx. Research into preservation strategies that decrease the risk of LIRI and PGD is needed, and ex-situ lung perfusion (ESLP) is the foremost technological advancement in this field. This review addresses three major topics in the field of LTx: first, we review the clinical manifestation of LIRI post-LTx; second, we discuss the pathophysiology of LIRI that leads to pulmonary endothelial inflammation and PGD; and third, we present the role of ESLP as a therapeutic vehicle to mitigate this physiologic insult, increase the rates of donor organ utilization, and improve patient outcomes.

Primary Graft Dysfunction

Primary graft dysfunction (PGD) is a form of acute lung injury after transplantation characterized by hypoxemia and the development of alveolar infiltrates on chest radiograph that occurs within 72 hours of reperfusion. PGD is among the most common early complications following lung transplantation and significantly contributes to increased short-term morbidity and mortality. In addition, severe PGD has been associated with higher 90-day and 1-year mortality rates compared with absent or less severe PGD and is a significant risk factor for the subsequent development of chronic lung allograft dysfunction. The International Society for Heart and Lung Transplantation released updated consensus guidelines in 2017, defining grade 3 PGD, the most severe form, by the presence of alveolar infiltrates and a ratio of PaO₂:FiO₂ less than 200. Multiple donor-related, recipient-related, and perioperative risk factors for PGD have been identified, many of which are potentially modifiable. Consistently identified risk factors include donor tobacco and alcohol use; increased recipient body mass index; recipient history of pulmonary hypertension, sarcoidosis, or pulmonary fibrosis; single lung transplantation; and use of cardiopulmonary bypass, among others. Several cellular pathways have been implicated in the pathogenesis of PGD, thus presenting several possible therapeutic targets for preventing and treating PGD. Notably, use of ex vivo lung perfusion (EVLP) has become more widespread and offers a potential platform to safely investigate novel PGD treatments while expanding the lung donor pool. Even in the presence of significantly prolonged ischemic times, EVLP has not been associated with an increased risk for PGD.

Chest X-ray Sizing for Lung Transplants Reflects Pulmonary Diagnosis and Body Composition and Is Associated With Primary Graft Dysfunction Risk

BACKGROUND

Donor-recipient oversizing based on predicted total lung capacity (pTLC) is associated with a reduced risk of primary graft dysfunction (PGD) following lung transplant but the effect varies with the recipient's diagnosis. Chest x-ray (CXR) measurements to estimate actual total lung capacity (TLC) could account for disease-related lung volume changes, but their role in size matching is unknown.

METHODS

We reviewed adult double lung transplant recipients 2007-2016 and measured apex-to-costophrenic-angle distance (=lung height) on pretransplant donor and recipient CXRs (oversized donor-recipient ratio >1; undersized ≤1]. We tested the relationship between recipient lung height to actual TLC; between lung height ratio and donor/recipient characteristics; and between both lung height ratio or pTLC ratio and grade 3 PGD with logistic regression.

RESULTS

Two hundred six patients were included and 32 (16%) developed grade 3 PGD at 48 or 72 hours. Recipient lung height was related to TLC (r2=0.7297). Pulmonary diagnosis, donor BMI, and recipient BMI were the major determinants of lung height ratio (AUC 0.9036). Lung height ratio oversizing was associated with increased risk of grade 3 PGD (odds ratio, 2.51; 95% confidence interval, 1.17-5.47; P = 0.0182) in this cohort, while pTLC ratio oversizing was not.

CONCLUSIONS

CXR lung height estimates actual TLC and reflects pulmonary diagnosis and body composition. Oversizing via CXR lung height ratio increased PGD risk moreso than pTLC-based oversizing in our cohort.

Predictors of nonuse of donation after circulatory death lung allografts

OBJECTIVE

Despite growing evidence of comparable outcomes in recipients of donation after circulatory death and donation after brain death donor lungs, donation after circulatory death allografts continue to be underused nationally. We examined predictors of nonuse.

METHODS

All donors who donated at least 1 organ for transplantation between 2005 and 2019 were identified in the United Network for Organ Sharing registry and stratified by donation type. The primary outcome of interest was use of pulmonary allografts. Organ disposition and refusal reasons were evaluated. Multivariable regression modeling was used to assess the relationship between donor factors and use.

RESULTS

A total of 15,458 donation after circulatory death donors met inclusion criteria. Of 30,916 lungs, 3.7% (1158) were used for transplantation and 72.8% were discarded primarily due to poor organ function. Consent was not requested in 8.4% of donation after circulatory death offers with donation after circulatory death being the leading reason (73.4%). Nonuse was associated with smoking history (P < .001), clinical infection with a blood source (12% vs 7.4%, P = .001), and lower PaO₂/FiO₂ ratio (median 230 vs 423, P < .001). In multivariable regression, those with PaO₂/FiO₂ ratio less than 250 were least likely to be transplanted (adjusted odds ratio, 0.03; P < .001), followed by cigarette use (0.28, P < .001), and donor age >50 (0.75, P = .031). Recent transplant era was associated with significantly increased use (adjusted odds ratio, 2.28; P < .001).

CONCLUSIONS

Nontransplantation of donation after circulatory death lungs was associated with potentially modifiable predonation factors, including organ procurement organizations' consenting behavior, and donor factors, including hypoxemia. Interventions to increase consent and standardize donation after circulatory death donor management, including selective use of ex vivo lung perfusion in the setting of hypoxemia, may increase use and the donor pool.

Prolonged Cold Ischemia Induces Necroptotic Cell Death in Ischemia-Reperfusion Injury and Contributes to Primary Graft Dysfunction after Lung Transplantation

Primary graft dysfunction (PGD) is a major cause of morbidity and mortality after lung transplantation. Ischemia-reperfusion injury (IRI) is a key event that contributes to PGD, though complex interactions affect donor lungs status, such as preceding brain death (BD), hemorrhagic shock (HS), and pre-engraftment lung management, the latter recognized as important risk factors for PGD. We hypothesized that a multi-hit isogenic mouse model of lung transplantation is more closely linked to PGD than IRI alone. Left lung transplants were performed between inbred C57BL/6 mice. A one-hit model of IRI was established by inducing cold ischemia (CI) of the donor lungs at 0°C for 1, 72, or 96 hours before engraftment. Multi-hit models were established by inducing 24 hours of HS and/or 3 hours of BD before 24 hours of CI. The recipients were killed at 24 hours after transplant and lung graft samples were analyzed. In the one-hit model of IRI, up to 72-hour CI time resulted in minimal cellular infiltration near small arteries after 24-hour reperfusion. Extension of CI time to 96 hours led to increased cellular infiltration and necroptotic pathway activation, without evidence of apoptosis, after 24-hour reperfusion. In a multi-hit model of PGD, "HS + BD + IRI" demonstrated increased lung injury, cellular infiltration, and activation of necroptotic and apoptotic pathways compared with IRI alone. Treatment with an inhibitor of receptor-interacting protein kinase 1 kinase, necrostatin-1, resulted in a significant decrease of downstream necroptotic pathway activation in both single- and multi-hit models of IRI. Thus, activation of necroptosis is a central event in IRI after prolonged CI, though it may not be sufficient to cause PGD alone. Pathological evaluation of donor lungs after CI-induced IRI, in conjunction with pre-engraftment donor lung factors in our multi-hit model, demonstrated early evidence of lung injury consistent with PGD. Our findings support the premise that pre-existing donor lung status is more important than CI time alone for inflammatory pathway activation in PGD, which may have important clinical implications for donor lung retrieval.

Normothermic ex vivo lung perfusion: Does the indication impact organ utilization and patient outcomes after transplantation?

BACKGROUND

Ex vivo lung perfusion (EVLP) is being increasingly applied as a method to evaluate and treat donor lungs for transplantation. However, with the previous limited worldwide experience, no studies have been able to evaluate the impact of indication for EVLP on organ utilization rates and recipient outcomes after lung transplantation (LTx). We examined these outcomes in a large-cohort, single-center series of clinical EVLP cases.

METHODS

All EVLP procedures performed at our institution between October 2008 and December 2017 were examined. The EVLPs were divided into 4 groups based on the indication for the procedure: group 1, high-risk brain death donors (HR-BDD); group 2, standard-risk donation after cardiac death (S-DCD); group 3, high-risk donation after cardiac death (HR-DCD); and group 4, logistics (LOGISTICS, the need for prolongation of preservation time or organ retrieval by a different transplantation team).

RESULTS

During the study period, a total of 1106 lung transplants were performed in our institution. In this period, 372 EVLPs were performed, 255 (69%) of which were accepted for transplantation, resulting in 262 transplants. Utilization rates were 70% (140 of 198) for group 1, 82% (40 of 49) for group 2, 63% (69 of 109) for group 3, and 81% (13 of 16) for group 4 (P = .42, Fisher's exact test). Recipient age (P = .27) and medical diagnosis (P = .31) were not different across the 4 groups. Kaplan-Meier survival by EVLP indication group demonstrated no differences. Thirty-day mortality was 2.1% in group 1, 5% in group 2, 2.9% in group 3, and 0% in group 4 (P = .87, Fisher's exact test). The median days of mechanical ventilation, intensive care unit stay, and hospital stay were 2, 4, and 21 in group 1; 2, 3, and 21 in group 2; 3, 5, and 28 in group 3; and 2, 4, and 17 in group 4 (P = .29, .17, and .09, respectively, Kruskal-Wallis rank-sum test).

CONCLUSIONS

Clinical implementation of EVLP has allowed our program to expand the annual lung transplantation activity by 70% in this time period. It has improved confidence in the utilization of DCD lungs and BDD lungs, with an average 70% utilization of post-EVLP treated donor lungs with excellent outcomes, while addressing significant challenges in donor lung assessment and the logistics of "real-life" clinical lung transplantation.

Review of donor and recipient surgical procedures in lung transplantation

Lung transplant remains the only durable treatment of end stage lung disease. Efficient surgical technique and preservation strategy are of critical importance in avoiding ischemia reperfusion injury and primary graft dysfunction (PGD), both associated with poorer outcomes. We present our surgical and preservation strategy for both donor and recipient procedures, including endobronchial and intracorporeal lung assessment, mediastinal dissection, lung preservation, donor pneumonectomy, back bench preparation, recipient approach, pneumonectomy, along with the bronchial, pulmonary artery, and pulmonary venous anastomoses.

Quantitative Evidence for Revising the Definition of Primary Graft Dysfunction after Lung Transplant

RATIONALE

Primary graft dysfunction (PGD) is a form of acute lung injury that occurs after lung transplantation. The definition of PGD was standardized in 2005. Since that time, clinical practice has evolved, and this definition is increasingly used as a primary endpoint for clinical trials; therefore, validation is warranted.

OBJECTIVES

We sought to determine whether refinements to the 2005 consensus definition could further improve construct validity.

METHODS

Data from the Lung Transplant Outcomes Group multicenter cohort were used to compare variations on the PGD definition, including alternate oxygenation thresholds, inclusion of additional severity groups, and effects of procedure type and mechanical ventilation. Convergent and divergent validity were compared for mortality prediction and concurrent lung injury biomarker discrimination.

MEASUREMENTS AND MAIN RESULTS

A total of 1,179 subjects from 10 centers were enrolled from 2007 to 2012. Median length of follow-up was 4 years (interquartile range = 2.4-5.9). No mortality differences were noted between no PGD (grade 0) and mild PGD (grade 1). Significantly better mortality discrimination was evident for all definitions using later time points (48, 72, or 48-72 hours; P < 0.001). Biomarker divergent discrimination was superior when collapsing grades 0 and 1. Additional severity grades, use of mechanical ventilation, and transplant procedure type had minimal or no effect on mortality or biomarker discrimination.

CONCLUSIONS

The PGD consensus definition can be simplified by combining lower PGD grades. Construct validity of grading was present regardless of transplant procedure type or use of mechanical ventilation. Additional severity categories had minimal impact on mortality or biomarker discrimination.

Cellular and acellular ex vivo lung perfusion preserve functional lung ultrastructure in a large animal model: a stereological study

Background

Ex vivo lung perfusion (EVLP) is used by an increasing number of transplant centres. It is still controversial whether an acellular or cellular (erythrocyte enriched) perfusate is preferable. The aim of this paper was to evaluate whether acellular (aEVLP) or cellular EVLP (cEVLP) preserves functional lung ultrastructure better and to generate a hypothesis regarding possible underlying mechanisms.

Methods

Lungs of 20 pigs were assigned to 4 groups: control, ischaemia (24 h), aEVLP and cEVLP (both EVLP groups: 24 h ischaemia + 12 h EVLP). After experimental procedures, whole lungs were perfusion fixed, samples for light and electron microscopic stereology were taken, and ventilation, diffusion and perfusion related parameters were estimated.

Results

Lung structure was well preserved in all groups. Lungs had less atelectasis and higher air content after EVLP. No significant group differences were found in alveolar septum composition or blood-air barrier thickness. Small amounts of intraalveolar oedema were detected in both EVLP groups but significantly more in aEVLP than in cEVLP.

Conclusions

Both EVLP protocols supported lungs well for up to 12 h and could largely prevent ischaemia ex vivo reperfusion associated lung injury. In both EVLP groups, oedema volume remained below the level of functional relevance. The group difference in oedema formation was possibly due to inferior septal perfusion in aEVLP.

Electronic supplementary material

The online version of this article (10.1186/s12931-018-0942-5) contains supplementary material, which is available to authorized users.

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

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

Perioperative Management of the Lung Graft Following Lung Transplantation

Perioperative management of patients undergoing lung transplantation is one of the most complex in cardiothoracic surgery. Certain perioperative interventions, such as mechanical ventilation, fluid management and blood transfusions, use of extracorporeal mechanical support, and pain management, may have significant impact on the lung graft function and clinical outcome. This article provides a review of perioperative interventions that have been shown to impact the perioperative course after lung transplantation.

Investigation of the preventive effect of proanthocyanidin in ischemia-reperfusion injury in lung transplantation: An experimental study

Background

This study aims to investigate the preventive effect of proanthocyanidin against ischemia-reperfusion injury after lung transplantation.

Methods

The study included 12 swines (weighing 35±5 kg) and separated into four groups. Groups 1 and 3 were identified as control groups and left upper lobectomy was performed. Groups 2 and 4 were identified as transplantation groups and left lower lobectomy and heterotransplantation were performed. Proanthocyanidin was only given to groups 3 and 4. Tissue samples were analyzed under light microscope and histopathological findings were recorded.

Results

There was no statistically significant difference between control groups in terms of the numerical values of histopathological findings that include congestion (p=0.565), alveolar edema (p=0.197) and peribronchial inflammation (p=0.444). However, numerical values of acute cellular rejection were statistically significantly different between transplantation groups (p=0.048). Mean oxidative stress enzyme levels were higher in group 2 compared to group 4; however, the difference was not statistically significant (p>0.05).

Conclusion

According to the findings of our experimental study, proanthocyanidin can be safely used in lung transplantation based on its preventive effect in ischemia-reperfusion injury that may lead to morbidity and mortality.

Primary graft dysfunction after heart transplantation: Incidence, trends, and associated risk factors

Changes in heart transplantation (HT) donor and recipient demographics may influence the incidence of primary graft dysfunction (PGD). We conducted a retrospective study to evaluate PGD incidence, trends, and associated risk factors by analyzing consecutive adult patients who underwent HT between January 2009 and December 2014 at our institution. Patients were categorized as having PGD using the International Society for Heart & Lung Transplantation (ISHLT)-defined criteria. Variables, including clinical and demographic characteristics of donors and recipients, were selected to assess their independent association with PGD. A time-trend analysis was performed over the study period. Three-hundred seventeen patients met inclusion criteria. Left ventricular PGD, right ventricular PGD, or both, were observed in 99 patients (31%). Risk factors independently associated with PGD included ischemic time, recipient African American race, and recipient amiodarone treatment. Over the study period, there was no change in the PGD incidence; however, there was an increase in the recipient pretransplantation use of amiodarone. The rate of 30-day mortality was significantly elevated in those with PGD versus those without PGD (6.06% vs 0.92%, P = .01). Despite recent advancements, incidence of PGD remains high. Understanding associated risk factors may allow for implementation of targeted therapeutic interventions.

Organ preservation: from the past to the future

Organ transplantation is the most effective therapy for patients with end-stage disease. Preservation solutions and techniques are crucial for donor organ quality, which is directly related to morbidity and survival after transplantation. Currently, static cold storage (SCS) is the standard method for organ preservation. However, preservation time with SCS is limited as prolonged cold storage increases the risk of early graft dysfunction that contributes to chronic complications. Furthermore, the growing demand for the use of marginal donor organs requires methods for organ assessment and repair. Machine perfusion has resurfaced and dominates current research on organ preservation. It is credited to its dynamic nature and physiological-like environment. The development of more sophisticated machine perfusion techniques and better perfusates may lead to organ repair/reconditioning. This review describes the history of organ preservation, summarizes the progresses that has been made to date, and discusses future directions for organ preservation.

Primary Graft Dysfunction After Lung Transplantation

Primary graft dysfunction is a form of acute injury after lung transplantation that is associated with significant short- and long-term morbidity and mortality. Multiple mechanisms contribute to the pathogenesis of primary graft dysfunction, including ischemia reperfusion injury, epithelial cell death, endothelial cell dysfunction, innate immune activation, oxidative stress, and release of inflammatory cytokines and chemokines. This article reviews the epidemiology, pathogenesis, risk factors, prevention, and treatment of primary graft dysfunction.

Role of biomarkers in early infectious complications after lung transplantation

Background

Infections and primary graft dysfunction are devastating complications in the immediate postoperative period following lung transplantation. Nowadays, reliable diagnostic tools are not available. Biomarkers could improve early infection diagnosis.

Methods

Multicentre prospective observational study that included all centres authorized to perform lung transplantation in Spain. Lung infection and/or primary graft dysfunction presentation during study period (first postoperative week) was determined. Biomarkers were measured on ICU admission and daily till ICU discharge or for the following 6 consecutive postoperative days.

Results

We included 233 patients. Median PCT levels were significantly lower in patients with no infection than in patients with Infection on all follow up days. PCT levels were similar for PGD grades 1 and 2 and increased significantly in grade 3. CRP levels were similar in all groups, and no significant differences were observed at any study time point. In the absence of PGD grade 3, PCT levels above median (0.50 ng/ml on admission or 1.17 ng/ml on day 1) were significantly associated with more than two- and three-fold increase in the risk of infection (adjusted Odds Ratio 2.37, 95% confidence interval 1.06 to 5.30 and 3.44, 95% confidence interval 1.52 to 7.78, respectively).

Conclusions

In the absence of severe primary graft dysfunction, procalcitonin can be useful in detecting infections during the first postoperative week. PGD grade 3 significantly increases PCT levels and interferes with the capacity of PCT as a marker of infection. PCT was superior to CRP in the diagnosis of infection during the study period.

Intratracheal Administration of Small Interfering RNA Targeting Fas Reduces Lung Ischemia-Reperfusion Injury

OBJECTIVES

Lung ischemia-reperfusion injury is the main cause of primary graft dysfunction after lung transplantation and results in increased morbidity and mortality. Fas-mediated apoptosis is one of the pathologic mechanisms involved in the development of ischemia-reperfusion injury. We hypothesized that the inhibition of Fas gene expression in lungs by intratracheal administration of small interfering RNA could reduce lung ischemia-reperfusion injury in an ex vivo model reproducing the procedural sequence of lung transplantation.

DESIGN

Prospective, randomized, controlled experimental study.

SETTING

University research laboratory.

SUBJECTS

C57/BL6 mice weighing 28-30 g.

INTERVENTIONS

Ischemia-reperfusion injury was induced in lungs isolated from mice, 48 hours after treatment with intratracheal small interfering RNA targeting Fas, control small interfering RNA, or vehicle. Isolated lungs were exposed to 6 hours of cold ischemia (4°C), followed by 2 hours of warm (37°C) reperfusion with a solution containing 10% of fresh whole blood and mechanical ventilation with constant low driving pressure.

MEASUREMENTS AND MAIN RESULTS

Fas gene expression was significantly silenced at the level of messenger RNA and protein after ischemia-reperfusion in lungs treated with small interfering RNA targeting Fas compared with lungs treated with control small interfering RNA or vehicle. Silencing of Fas gene expression resulted in reduced edema formation (bronchoalveolar lavage protein concentration and lung histology) and improvement in lung compliance. These effects were associated with a significant reduction of pulmonary cell apoptosis of lungs treated with small interfering RNA targeting Fas, which did not affect cytokine release and neutrophil infiltration.

CONCLUSIONS

Fas expression silencing in the lung by small interfering RNA is effective against ischemia-reperfusion injury. This approach represents a potential innovative strategy of organ preservation before lung transplantation.

Telomere length in patients with pulmonary fibrosis associated with chronic lung allograft dysfunction and post-lung transplantation survival

BACKGROUND

Prior studies have shown that patients with pulmonary fibrosis with mutations in the telomerase genes have a high rate of certain complications after lung transplantation. However, few studies have investigated clinical outcomes based on leukocyte telomere length.

METHODS

We conducted an observational cohort study of all patients with pulmonary fibrosis who underwent lung transplantation at a single center between January 1, 2007, and December 31, 2014. Leukocyte telomere length was measured from a blood sample collected before lung transplantation, and subjects were stratified into 2 groups (telomere length <10th percentile vs ≥10th percentile). Primary outcome was post-lung transplant survival. Secondary outcomes included incidence of allograft dysfunction, non-pulmonary organ dysfunction, and infection.

RESULTS

Approximately 32% of subjects had a telomere length <10th percentile. Telomere length <10th percentile was independently associated with worse survival (hazard ratio 10.9, 95% confidence interval 2.7-44.8, p = 0.001). Telomere length <10th percentile was also independently associated with a shorter time to onset of chronic lung allograft dysfunction (hazard ratio 6.3, 95% confidence interval 2.0-20.0, p = 0.002). Grade 3 primary graft dysfunction occurred more frequently in the <10th percentile group compared with the ≥10th percentile group (28% vs 7%; p = 0.034). There was no difference between the 2 groups in incidence of acute cellular rejection, cytopenias, infection, or renal dysfunction.

CONCLUSIONS

Telomere length <10th percentile was associated with worse survival and shorter time to onset of chronic lung allograft dysfunction and thus represents a biomarker that may aid in risk stratification of patients with pulmonary fibrosis before lung transplantation.

Protein biomarkers associated with primary graft dysfunction following lung transplantation

Severe primary graft dysfunction affects 15-20% of lung transplant recipients and carries a high mortality risk. In addition to known donor, recipient, and perioperative clinical risk factors, numerous biologic factors are thought to contribute to primary graft dysfunction. Our current understanding of the pathogenesis of lung injury and primary graft dysfunction emphasizes multiple pathways leading to lung endothelial and epithelial injury. Protein biomarkers specific to these pathways can be measured in the plasma, bronchoalveolar lavage fluid, and lung tissue. Clarification of the pathophysiology and timing of primary graft dysfunction could illuminate predictors of dysfunction, allowing for better risk stratification, earlier identification of susceptible recipients, and development of targeted therapies. Here, we review much of what has been learned about the association of protein biomarkers with primary graft dysfunction and evaluate this association at different measurement time points.

Onset of Inflammation With Ischemia: Implications for Donor Lung Preservation and Transplant Survival

Lungs stored ahead of transplant surgery experience ischemia. Pulmonary ischemia differs from ischemia in the systemic organs in that stop of blood flow in the lung leads to loss of shear alone because the lung parenchyma does not rely on blood flow for its cellular oxygen requirements. Our earlier studies on the ischemia-induced mechanosignaling cascade showed that the pulmonary endothelium responds to stop of flow by production of reactive oxygen species (ROS). We hypothesized that ROS produced in this way led to induction of proinflammatory mediators. In this study, we used lungs or cells subjected to various periods of storage and evaluated the induction of several proinflammatory mediators. Isolated murine, porcine and human lungs in situ showed increased expression of cellular adhesion molecules; the damage-associated molecular pattern protein high-mobility group box 1 and the corresponding pattern recognition receptor, called the receptor for advanced glycation end products; and induction stabilization and translocation of hypoxia-inducible factor 1α and its downstream effector VEGFA, all of which are participants in inflammation. We concluded that signaling with lung preservation drives expression of inflammatory mediators that potentially predispose the donor lung to an inflammatory response after transplant.

Increased Intraoperative Fluid Administration Is Associated with Severe Primary Graft Dysfunction After Lung Transplantation

BACKGROUND

Severe primary graft dysfunction (PGD) is a major cause of early morbidity and mortality in patients after lung transplantation. The etiology and pathophysiology of PGD is not fully characterized and whether intraoperative fluid administration increases the risk for PGD remains unclear from previous studies. Therefore, we tested the hypothesis that increased total intraoperative fluid volume during lung transplantation is associated with the development of grade-3 PGD.

METHODS

This retrospective cohort analysis included patients who had lung transplantation at the Cleveland Clinic between January 2009 and June 2013. We used multivariable logistic regression with adjustment for donor, recipient, and perioperative confounding factors to examine the association between total intraoperative fluid administration and development of grade-3 PGD in the initial 72 postoperative hours. Secondary outcomes included time to initial extubation and intensive care unit length of stay.

RESULTS

Grade-3 PGD occurred in 123 of 494 patients (25%) who had lung transplantation. Patients with grade-3 PGD received a larger volume of intraoperative fluid (median 5.0 [3.8, 7.5] L) than those without grade-3 PGD (3.9 [2.8, 5.2] L). Each intraoperative liter of fluid increased the odds of grade-3 PGD by approximately 22% (adjusted odds ratio, 1.22; 95% confidence interval [CI], 1.12-1.34; P <0.001). The volume of transfused red blood cell concentrate was associated with grade-3 PGD (1.1 [0.0, 1.8] L for PGD-3 vs 0.4 [0.0, 1.1 for nongrade-3 PGD] L; adjusted odds ratio, 1.7; 95% CI, 1.08-2.7; P = 0.002). Increased fluid administration was associated with longer intensive care unit stay (adjusted hazard ratio, 0.92; 97.5% CI, 0.88-0.97; P < 0.001) but not with time to initial tracheal extubation (hazard ratio, 0.97; 97.5% CI, 0.93-1.02; P = 0.17).

CONCLUSIONS

Increased intraoperative fluid volume is associated with the most severe form of PGD after lung transplant surgery. Limiting fluid administration may reduce the risk for development of grade-3 PGD and thus improve early postoperative morbidity and mortality after lung transplantation.

The relationship between plasma lipid peroxidation products and primary graft dysfunction after lung transplantation is modified by donor smoking and reperfusion hyperoxia

BACKGROUND

Donor smoking history and higher fraction of inspired oxygen (FIO2) at reperfusion are associated with primary graft dysfunction (PGD) after lung transplantation. We hypothesized that oxidative injury biomarkers would be elevated in PGD, with higher levels associated with donor exposure to cigarette smoke and recipient hyperoxia at reperfusion.

METHODS

We performed a nested case-control study of 72 lung transplant recipients from the Lung Transplant Outcomes Group cohort. Using mass spectroscopy, F2-isoprostanes and isofurans were measured in plasma collected after transplantation. Cases were defined in 2 ways: grade 3 PGD present at day 2 or day 3 after reperfusion (severe PGD) or any grade 3 PGD (any PGD).

RESULTS

There were 31 severe PGD cases with 41 controls and 35 any PGD cases with 37 controls. Plasma F2-isoprostane levels were higher in severe PGD cases compared with controls (28.6 pg/ml vs 19.8 pg/ml, p = 0.03). Plasma F2-isoprostane levels were higher in severe PGD cases compared with controls (29.6 pg/ml vs 19.0 pg/ml, p = 0.03) among patients reperfused with FIO2 >40%. Among recipients of lungs from donors with smoke exposure, plasma F2-isoprostane (38.2 pg/ml vs 22.5 pg/ml, p = 0.046) and isofuran (66.9 pg/ml vs 34.6 pg/ml, p = 0.046) levels were higher in severe PGD compared with control subjects.

CONCLUSIONS

Plasma levels of lipid peroxidation products are higher in patients with severe PGD, in recipients of lungs from donors with smoke exposure, and in recipients exposed to higher Fio2 at reperfusion. Oxidative injury is an important mechanism of PGD and may be magnified by donor exposure to cigarette smoke and hyperoxia at reperfusion.

Lung transplantation in IIP: A review

The idiopathic interstitial pneumonias (IIP) encompass a large and diverse subtype of interstitial lung disease (ILD) with idiopathic pulmonary fibrosis (IPF) and non-specific interstitial pneumonia (NSIP) being the most common types. Although pharmacologic treatments are available for most types of IIP, many patients progress to advanced lung disease and require lung transplantation. Close monitoring with serial functional and radiographic tests for disease progression coupled with early referral for lung transplantation are of great importance in the management of patients with IIP. Both single and bilateral lung transplantation are acceptable procedures for IIP. Procedure selection is a complex decision influenced by multiple factors related to patient, donor and transplant centre. While single lung transplant may reduce waitlist time and mortality, the long-term outcomes after bilateral lung transplantation may be slightly superior. There are numerous complications following lung transplantation including primary graft dysfunction, chronic lung allograft dysfunction (CLAD), infections, gastroesophageal reflux disease (GERD) and airway disease that limit post-transplant longevity. The median survival after lung transplantation is 4.7 years in patients with ILD, which is less than in patients with other underlying lung diseases. Although long-term survival is limited, this intervention still conveys a survival benefit and improved quality of life in suitable IIP patients with advanced lung disease and chronic hypoxemic respiratory failure.

Primary Graft Dysfunction after Lung Transplantation

Primary graft dysfunction (PGD) is a severe form of acute lung injury that is a major cause of early morbidity and mortality encountered after lung transplantation. PGD is diagnosed by pulmonary oedema with diffuse alveolar damage that manifests clinically as progressive hypoxemia with radiographic pulmonary infiltrates. Inflammatory and immunological response caused by ischaemia and reperfusion is important with regard to pathophysiology. PGD affects short- and long-term outcomes, the donor organ is the leading factor affecting these adverse ramifications. To minimize the risk of PGD, reduction of lung ischaemia time, reperfusion optimisation, prostaglandin level regulation, haemodynamic control, hormone replacement therapy, ventilator management are carried out; for research regarding donor lung preparation strategies, certain procedures are recommended. In this review, recent updates in epidemiology, pathophysiology, molecular and genetic biomarkers and technical developments affecting PGD are described.

Primary graft dysfunction: lessons learned about the first 72 h after lung transplantation

PURPOSE OF REVIEW

In 2005, the International Society for Heart and Lung Transplantation published a standardized definition of primary graft dysfunction (PGD), facilitating new knowledge on this form of acute lung injury that occurs within 72 h of lung transplantation. PGD continues to be associated with significant morbidity and mortality. This article will summarize the current literature on the epidemiology of PGD, pathogenesis, risk factors, and preventive and treatment strategies.

RECENT FINDINGS

Since 2011, several manuscripts have been published that provide insight into the clinical risk factors and pathogenesis of PGD. In addition, several transplant centers have explored preventive and treatment strategies for PGD, including the use of extracorporeal strategies. More recently, results from several trials assessing the role of extracorporeal lung perfusion may allow for much-needed expansion of the donor pool, without raising PGD rates.

SUMMARY

This article will highlight the current state of the science regarding PGD, focusing on recent advances, and set a framework for future preventive and treatment strategies.

Clinical risk factors for primary graft dysfunction in a low-volume lung transplantation center

Primary graft dysfunction (PGD) is a severe acute lung injury syndrome following lung transplantation. Previous studies of clinical risk factors, including a multicenter prospective cohort trial, have identified a number of recipient, donor, and operative variables related to Grade 3 PGD. The aim of this study was to validate these risk factors in a lung transplantation center with a low volume of procedures. We conducted a retrospective cohort study of 45 consecutive lung transplantations performed between January 2011 and September 2013. PGD was defined according to the International Society for Heart and Lung Transplantation grading scale. Risk factors were evaluated independently and the significant confounders entered into multivariable logistic regression models. The overall incidence of Grade 3 PGD was 35.5% at T24, 17.7% at T48, and 15.5% at T72. The following risk factors were associated with Grade 3 PGD at the indicated time points: recipient female gender at T24 (P=.034), mixed diagnoses at T72 (P=.047), ECMO bridge-to-lung transplantation at T24 (P=.0004) and at T48 (P=.038), donor causes of death different from stroke and trauma at T24 (P=.019) and T72 (P=.014), blood transfusions during surgery at T24 (P=.001), intraoperative venoarterial ECMO T24 (P<.0001). Multivariate analysis at T24 identified recipient female gender and intraoperative venoarterial ECMO as risk factors (P=.010 and P=.018, respectively). This study demonstrated that risk factors for severe PGD in a low-volume center were similar to international reports in prevalence and type. ECMO bridge-to-lung transplantation emerged as a risk factor previously underestimated.

Evaluating acellular versus cellular perfusate composition during prolonged ex vivo lung perfusion after initial cold ischaemia for 24 hours

Normothermic ex vivo lung perfusion (EVLP) has developed as a powerful technique to evaluate particularly marginal donor lungs prior to transplantation. In this study, acellular and cellular perfusate compositions were compared in an identical experimental setting as no consensus has been reached on a preferred technique yet. Porcine lungs underwent EVLP for 12 h on the basis of an acellular or a cellular perfusate composition after 24 h of cold ischaemia as defined organ stress. During perfusion, haemodynamic and respiratory parameters were monitored. After EVLP, the lung condition was assessed by light and transmission electron microscopy. Aerodynamic parameters did not show significant differences between groups and remained within the in vivo range during EVLP. Mean oxygenation indices were 491 ± 39 in the acellular group and 513 ± 53 in the cellular group. Groups only differed significantly in terms of higher pulmonary artery pressure and vascular resistance in the cellular group. Lung histology and ultrastructure were largely well preserved after prolonged EVLP and showed only minor structural alterations which were similarly present in both groups. Prolonged acellular and cellular EVLP for 12 h are both feasible with lungs prechallenged by ischaemic organ stress. Physiological and ultrastructural analysis showed no superiority of either acellular or cellular perfusate composition.

Role of genetics in lung transplant complications

There is increasing knowledge that patients can be predisposed to a certain disease by genetic variations in their DNA. Extensive genetic variation has been described in molecules involved in short- and long-term complications after lung transplantation (LTx), such as primary graft dysfunction (PGD), acute rejection, respiratory infection, chronic lung allograft dysfunction (CLAD), and mortality. Several of these studies could not be confirmed or were not reproduced in other cohorts. However, large multicenter prospective studies need to be performed to define the real clinical consequence and significance of genotyping the donor and receptor of a LTx. The current review presents an overview of genetic polymorphisms (SNP) investigating an association with different complications after LTx. Finally, the major drawbacks, clinical relevance, and future perspectives will be discussed.

Method of isolated ex vivo lung perfusion in a rat model: lessons learned from developing a rat EVLP program

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. As this technology expands and improves, the ability to potentially evaluate and improve the quality of substandard lungs prior to transplant is a critical need. In order to more rigorously evaluate these approaches, a reproducible animal model needs to be established that would allow for testing of improved techniques and management of the donated lungs as well as to the lung-transplant recipient. In addition, an EVLP animal model of associated pathologies, e.g., ventilation induced lung injury (VILI), would provide a novel method to evaluate treatments for these pathologies. Here, we describe the development of a rat EVLP lung program and refinements to this method that allow for a reproducible model for future expansion. We also describe the application of this EVLP system to model VILI in rat lungs. The goal is to provide the research community with key information and “pearls of wisdom”/techniques that arose from trial and error and are critical to establishing an EVLP system that is robust and reproducible.

Lung preconditioning in anesthesia: Review of the literature

Lung injury can arise during or after anesthesia and can lead to a complicated postoperative course with great implications for the patient. Unfortunately, treatment of acute lung injury is at the moment mainly supportive and rates of recovery have not really improved in the recent years. In many cases, lung injury can be anticipated and preventive measures seem possible. This represents a unique challenge to the anesthesiologist, as some new opportunities to reduce the frequency and/or severity of lung injury seem now available. These chances may arise from the potency of preconditioning the lungs before the main injury, with smaller injurious insults. Although preconditioning began to be applicated first on the myocardium, experimental studies have shown potentially beneficial results also for the lungs. This review summarizes the main methods of lung preconditioning that have been tried in experimental studies in the literature and the main mechanisms that are perhaps involved. Emphasis is given in the two main methods of preconditioning that seem readily applicable in the clinical praxis, that is ischemic preconditioning, as well as preconditioning with volatile anesthetics. The few, but interesting clinical studies are also summarized and the future research points in this evolving field of anesthesia are stressed.

Recipient-related clinical risk factors for primary graft dysfunction after lung transplantation: a systematic review and meta-analysis

Background

Primary graft dysfunction (PGD) is the main cause of early morbidity and mortality after lung transplantation. Previous studies have yielded conflicting results for PGD risk factors. Herein, we carried out a systematic review and meta-analysis of published literature to identify recipient-related clinical risk factors associated with PGD development.

Method

A systematic search of electronic databases (PubMed, Embase, Web of Science, Cochrane CENTRAL, and Scopus) for studies published from 1970 to 2013 was performed. Cohort, case-control, or cross-sectional studies that examined recipient-related risk factors of PGD were included. The odds ratios (ORs) or mean differences (MDs) were calculated using random-effects models

Result

Thirteen studies involving 10042 recipients met final inclusion criteria. From the pooled analyses, female gender (OR 1.38, 95% CI 1.09 to 1.75), African American (OR 1.82, 95%CI 1.36 to 2.45), idiopathic pulmonary fibrosis (IPF) (OR 1.78, 95% CI 1.49 to 2.13), sarcoidosis (OR 4.25, 95% CI 1.09 to 16.52), primary pulmonary hypertension (PPH) (OR 3.73, 95%CI 2.16 to 6.46), elevated BMI (BMI≥25 kg/m²) (OR 1.83, 95% CI 1.26 to 2.64), and use of cardiopulmonary bypass (CPB) (OR 2.29, 95%CI 1.43 to 3.65) were significantly associated with increased risk of PGD. Age, cystic fibrosis, secondary pulmonary hypertension (SPH), intra-operative inhaled nitric oxide (NO), or lung transplant type (single or bilateral) were not significantly associated with PGD development (all P>0.05). Moreover, a nearly 4 fold increased risk of short-term mortality was observed in patients with PGD (OR 3.95, 95% CI 2.80 to 5.57).

Conclusions

Our analysis identified several recipient related risk factors for development of PGD. The identification of higher-risk recipients and further research into the underlying mechanisms may lead to selective therapies aimed at reducing this reperfusion injury.

Effects of methylprednisolone on inflammatory activity and oxidative stress in the lungs of brain-dead rats

OBJECTIVE:

To evaluate the effects that early and late systemic administration of methylprednisolone have on lungs in a rat model of brain death.

METHODS:

Twenty-four male Wistar rats were anesthetized and randomly divided into four groups (n = 6 per group): sham-operated (sham); brain death only (BD); brain death plus methylprednisolone (30 mg/kg i.v.) after 5 min (MP5); and brain death plus methylprednisolone (30 mg/kg i.v.) after 60 min (MP60). In the BD, MP5, and MP60 group rats, we induced brain death by inflating a balloon catheter in the extradural space. All of the animals were observed and ventilated for 120 min. We determined hemodynamic and arterial blood gas variables; wet/dry weight ratio; histological score; levels of thiobarbituric acid reactive substances (TBARS); superoxide dismutase (SOD) activity; and catalase activity. In BAL fluid, we determined differential white cell counts, total protein, and lactate dehydrogenase levels. Myeloperoxidase activity, lipid peroxidation, and TNF-α levels were assessed in lung tissue.

RESULTS:

No significant differences were found among the groups in terms of hemodynamics, arterial blood gases, wet/dry weight ratio, BAL fluid analysis, or histological score-nor in terms of SOD, myeloperoxidase, and catalase activity. The levels of TBARS were significantly higher in the MP5 and MP60 groups than in the sham and BD groups (p < 0.001). The levels of TNF-α were significantly lower in the MP5 and MP60 groups than in the BD group (p < 0.001).

CONCLUSIONS:

In this model of brain death, the early and late administration of methylprednisolone had similar effects on inflammatory activity and lipid peroxidation in lung tissue.