A Survey of Clinical Practice of Lung Transplantation in North America

Immunopathology of lung transplantation: from infection to rejection and vice versa

Lung transplantation offers a lifesaving option for patients with end-stage lung disease, but it is marred by a high risk of post-transplant infections, particularly involving multidrug-resistant bacteria, Cytomegalovirus, and fungal pathogens. This elevated infection rate, the highest among solid organ transplants, poses a significant challenge for clinicians, particularly within the first year post-transplantation, where infections are the leading cause of mortality. The direct exposure of lung allografts to the external environment exacerbates this vulnerability leading to constant immune stimulation and consequently to an elevated risk of triggering alloimmune responses to the lung allograft. The necessity of prolonged immunosuppression to prevent allograft rejection further complicates patient management by increasing susceptibility to infections and neoplasms, and complicating the differentiation between rejection and infection, which require diametrically opposed management strategies. This review explores the intricate balance between preventing allograft rejection and managing the heightened infection risk in lung transplant recipients.

Acute rejection post lung transplant

PURPOSE OF REVIEW

To review what is currently known about the pathogenesis, diagnosis, treatment, and prevention of acute rejection (AR) in lung transplantation.

RECENT FINDINGS

Epigenomic and transcriptomic methods are gaining traction as tools for earlier detection of AR, which still remains primarily a histopathologic diagnosis.

SUMMARY

Acute rejection is a common cause of early posttransplant lung graft dysfunction and increases the risk of chronic rejection. Detection and diagnosis of AR is primarily based on histopathology, but noninvasive molecular methods are undergoing investigation. Two subtypes of AR exist: acute cellular rejection (ACR) and antibody-mediated rejection (AMR). Both can have varied clinical presentation, ranging from asymptomatic to fulminant ARDS, and can present simultaneously. Diagnosis of ACR requires transbronchial biopsy; AMR requires the additional measuring of circulating donor-specific antibody (DSA) levels. First-line treatment in ACR is increased immunosuppression (pulse-dose or tapered dose glucocorticoids); refractory cases may need antibody-based lymphodepletion therapy. First line treatment in AMR focuses on circulating DSA removal with B and plasma cell depletion; plasmapheresis, intravenous human immunoglobulin (IVIG), bortezomib, and rituximab are often employed.

Systemic corticosteroids for outpatient respiratory viral infections in lung transplant recipients

INTRODUCTION

Respiratory viral infections (RVI) in lung transplant recipients (LTR) have variably been associated with rejection and chronic lung allograft dysfunction. Our center has used systemic corticosteroids to treat outpatient RVI in some cases, but evidence is limited. We reviewed all adult LTR diagnosed with outpatient RVI January 2017 to December 2019. The primary outcome was recovery of lung function (forced expiratory volume in 1 s [FEV1]) at next stable visit between 1 and 12 months postinfection, expressed as a ratio over stable preinfection FEV1 (FEV1 recovery ratio).

METHODS

We identified 100 adult LTR with outpatient RVI diagnoses eligible for study, 36% of whom received corticosteroids. We modelled the adjusted association between corticosteroid use and FEV1 recovery ratio using linear regression.

RESULTS

Steroid-treated patients had a lower FEV1 presentation ratio (0.92 vs. 1.04, p = .0070) and were more likely to have chronic lung allograft dysfunction at time of infection (25% vs. 5%, p = .0077). Mean FEV1 recovery ratio was 1.02 (SD 0.19) with no association with corticosteroid therapy via multivariable linear regression (p = .5888).

CONCLUSIONS

Steroid treatment was not associated with FEV1 recovery. This suggests corticosteroids may not have a role in the management of RVI in this population.

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.

Modulation of tissue resident memory T cells by glucocorticoids after acute cellular rejection in lung transplantation

Acute cellular rejection is common after lung transplantation and is associated with an increased risk of early chronic rejection. We present combined single-cell RNA and TCR sequencing on recipient-derived T cells obtained from the bronchoalveolar lavage of three lung transplant recipients with rejection and compare them with T cells obtained from the same patients after treatment of rejection with high-dose systemic glucocorticoids. At the time of rejection, we found an oligoclonal expansion of cytotoxic CD8+ T cells that all persisted as tissue resident memory T cells after successful treatment. Persisting CD8+ allograft-resident T cells have reduced gene expression for cytotoxic mediators after therapy with glucocorticoids but accumulate around airways. This clonal expansion is discordant with circulating T cell clonal expansion at the time of rejection, suggesting in situ expansion. We thus highlight the accumulation of cytotoxic, recipient-derived tissue resident memory T cells within the lung allograft that persist despite the administration of high-dose systemic glucocorticoids. The long-term clinical consequences of this persistence have yet to be characterized.

The outcome of lung transplantation for end-stage pulmonary diseases with pulmonary hypertension: a single-center experience

BACKGROUND

Lung transplantation is a treatment for end-stage lung disease. The optimal transplant strategy for patients with end-stage lung disease complicated by pulmonary hypertension (PH) is controversial. The aim of this study is to review this experience and analyze the outcomes of lung transplantation for PH.

METHODS

This retrospective study collected data on patients with PH undergoing lung transplantation between March 2016 and December 2019 at a single center in China. The perioperative features and short- and medium-term outcomes between single-lung transplantation (SLT) and double-lung transplantation (DLT) were compared. Kaplan-Meier methods were used to analyze overall survival across a variety of transplantation procedures, age, mean pulmonary artery pressure (mPAP), body mass index (BMI), and indications of transplantation.

RESULTS

A total of 63 patients with PH were finally included in the analysis. The mean age, mean BMI, and mPAP were 56.37 years, 19.56 kg/m², and 35.4 mmHg respectively. The overall 1-, 2-, and 3-year survival was 70%, 63%, and 60%, respectively. Five (7.94%) patients died within 30 days after surgery and nine patients (14.3%) died from infection during the followed-up period. There were no significant differences in the short- and medium-term survival outcomes of SLT and DLT, but postoperative pulmonary function was better in DLT. Patients older than 60 years of age had worse survival (P=0.01).

CONCLUSIONS

The short- and medium-term survival outcomes between SLT and DLT are similar in selected patients with PH. DLT provides better pulmonary function. Patients older than 60 years are associated with worse survival.

Acute rejection and post lung transplant surveillance

Purpose

The purpose of this review is to summarize the current evidence on the evaluation and treatment of acute rejection after lung transplantation.

Results

Despite significant progress in the field of transplant immunology, acute rejection remains a frequent complication after transplantation. Almost 30% of lung transplant recipients experience at least one episode of acute cellular rejection (ACR) during the first year after transplant. Acute cellular rejection, lymphocytic bronchiolitis, and antibody-mediated rejection (AMR) are all risk factors for the subsequent development of chronic lung allograft dysfunction (CLAD). Acute cellular rejection and lymphocytic bronchiolitis have well-defined histopathologic diagnostic criteria and grading. The diagnosis of antibody-mediated rejection after lung transplantation requires a multidisciplinary approach. Antibody-mediated rejection may cause acute allograft failure.

Conclusions

Acute rejection is a risk factor for development of chronic rejection. Further investigations are required to better define risk factors, surveillance strategies, and optimal management strategies for acute allograft rejection.

Donor-Derived Cell-Free DNA for Acute Rejection Monitoring in Heart and Lung Transplantation

PURPOSE OF REVIEW

Acute allograft rejection is a common cause of morbidity and mortality in heart and lung transplantation. Unfortunately, the current monitoring gold standard-biopsy plus histopathology-has several limitations. Plasma donor-derived cell-free DNA (dd-cfDNA) has emerged as a potentially valuable biomarker for rejection that addresses some of the limitations of biopsy. This review covers the current state of the evidence and future directions for the use of dd-cfDNA in the monitoring of acute rejection.

RECENT FINDINGS

The results of several observational cohort studies demonstrate that levels of dd-cfDNA increase in the setting of acute cellular rejection and antibody-mediated rejection in both heart and lung transplant recipients. dd-cfDNA demonstrates acceptable performance characteristics, but low specificity for the detection of underlying injury from rejection or infection. In particular, the high negative predictive value of the test in both heart and lung transplant patients provides the potential for its use as a screening tool for the monitoring of allograft health rather than tissue biopsy alone.

SUMMARY

Existing evidence shows that dd-cfDNA is a safe, convenient, and reliable method of acute rejection monitoring in heart and lung transplant recipients. Further studies are required to validate threshold values for clinical use and determine its role in the diagnosis of alternative forms of allograft injury.

Optimal Methods to Secure Extracorporeal Membrane Oxygenation Bicaval Dual-Lumen Cannulae: What Works?

Ambulation while on extracorporeal membrane oxygenation (ECMO) is critical to facilitate native pulmonary recovery for patients with acute respiratory failure and is a prerequisite for listing for lung transplantation to achieve optimal outcomes. The development of a bicaval dual-lumen cannula capable of providing venovenous (VV) ECMO support via the internal jugular vein has greatly facilitated ambulation and rehabilitation programs. But cannula dislodgement is a serious concern with ambulation and rehabilitation, especially when minor cannula migration can significantly impact VV-ECMO flow. We review an optimal technique to secure dual-lumen cannula to facilitate early mobility, ambulation, and rehabilitation and prevent ECMO cannula dislodgement.

Detection, classification, and management of rejection after lung transplantation

Rejection is a major complication following lung transplantation. Acute cellular rejection, lymphocytic bronchiolitis, and antibody-mediated rejection (AMR) are all risk factors for the subsequent development of chronic lung allograft dysfunction (CLAD). Acute cellular rejection and lymphocytic bronchiolitis have well defined histopathologic diagnostic criteria and grading. Diagnosis of AMR requires a multidisciplinary approach. CLAD is the major barrier to long-term survival following lung transplantation. The most common phenotype of CLAD is bronchiolitis obliterans syndrome (BOS) which is defined by a persistent obstructive decline in lung function. Restrictive allograft dysfunction (RAS) is a second phenotype of CLAD and is associated with a worse prognosis. This article will review the diagnosis, staging, clinical presentation, and treatment of acute rejection, AMR, and CLAD following lung transplantation.

The outcomes of 80 lung transplants in a single center from Saudi Arabia

BACKGROUND

Lung transplantation has become a standard of care for a select group of patients with advanced lung diseases. Lung transplantation has undergone rapid growth in the last few years in Saudi Arabia.

OBJECTIVE

Describe five years of experience with lung transplantation.

DESIGN

Retrospective, descriptive.

SETTINGS

Major tertiary care hospital.

PATIENTS

All patients who underwent lung transplant surgery between 2010 to 2015.

MAIN OUTCOME MEASURES

Indications for lung transplant demographics, body mass index, blood group, type of transplant surgery, morbidity rate using the Clavien-Dindo classification, rate of early- and late-onset bronchiolitis obliterans syndrome (BOS), bronchiolitis obliterans-free survival, 30- and 90-day mortality rate, and survival (30 days, 90 days, 1-year, 3-years and 5-years) for lung transplant recipients. The duration of mechanical ventilation, colonization by bacteria and need for lung volume reduction surgery for lung donors.

SAMPLE SIZE

80, 45% women and 55% men.

RESULTS

The most common indication for lung transplant in Saudi Arabia is pulmonary fibrosis (45%), followed by non-cystic fibrosis bronchiectasis (25%) and cystic fibrosis-related bronchiectasis (20%). Only 45% of our lung transplant recipients had a normal BMI (18-28 kg/m2). The most frequent blood group was A (40%), followed by blood group O (32.5%). Most (85%) lung transplants were bilateral while 15% were single lung transplants. Postoperative complications developed in 64 patients, 34 (42.5%) had minor grade 1 complications, while 13 (16.5%) had severe complications leading to death (grade V). Early onset BOS developed in 6 (7.5%) patients while 16 (20%) had late onset BOS. The BOS-free survival rate was 72.5%. The mean duration of mechanical ventilation in lung donors was 9 days and most were infected by bacteria. The majority of recipients required lung volume reduction. The 30-day mortality rate was 12.5% and the 90-day mortality rate was 17.5%. Survival rates at our center were 87.5% at 30 days, 82.5% at 90 days, 81.2% at 1 year, 67.9% at 2 years and 62.1% at 5 years.

CONCLUSIONS

Lung transplantation has become an invaluable approach for the treatment of end-stage respiratory disease. Our 5-year experience has shown exciting promises for lung transplantation in Saudi Arabia.

LIMITATIONS

Retrospective design, single center experience.

CONFLICT OF INTEREST

None.

Antifungal prophylaxis in lung transplant: A survey of United States' transplant centers

BACKGROUND

Antifungal prophylaxis strategies for lung transplant recipients vary without consensus or standard of care. Our current study aims to identify antifungal prophylaxis practices in the United States.

METHODS

From November 29, 2018, to February 15, 2019, we emailed surveys to medical directors of adult lung transplant centers. An alternate physician representative was approached if continued non-response after three survey attempts. Descriptive statistics were used to report findings.

RESULTS

Forty-four of 62 (71.0%) eligible centers responded. All Organ Procurement and Transplantation Networks were represented. Only four (9.1%) centers used pre-transplant prophylaxis for prevention of tracheobronchitis (3 of 4) and invasive fungal disease (4 of 4). Thirty-nine of forty (97.5%) centers used post-transplant prophylaxis: 36 (90.0%) universal and 3 (7.5%) pre-emptive/selective prophylaxis. Most centers used nebulized amphotericin with a systemic agent (26 of 36, 72.2%). Thirty-two of thirty-six (88.9%) centers continued universal prophylaxis beyond the hospital setting. Duration of prophylaxis ranged from the post-transplant hospitalization to lifelong with most centers (25 of 36, 69.4%) discontinuing prophylaxis 6 months or less post-transplant.

CONCLUSION

Most United States' lung transplant centers utilize a universal prophylaxis with nebulized amphotericin and a systemic triazole for 6 months or less post-transplant. Very few centers use pre-transplant antifungal prophylaxis.

Lung transplantation for idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with a poor prognosis. Lung transplantation is the only intervention shown to increase life expectancy for patients with IPF, but it is associated with disease-specific challenges. In this Review, we discuss the importance of a proactive approach to the management of IPF comorbidities, including gastro-oesophageal reflux, pulmonary hypertension, coronary artery disease, and malignancy. With a donor pool too small to meet demand and unacceptably high mortality on transplant waiting lists, we discuss different systems used internationally to facilitate organ allocation. We explore the rapidly evolving landscape of transplantation for patients with IPF with regards to antifibrotic therapy, technological advances in extracorporeal life support, advances in understanding of the genetics of the disease, and the importance of a holistic multidisciplinary approach to care. Finally, we consider potential advances over the next decade that are envisaged to improve transplantation outcomes in patients with advanced IPF.

Medical Course and Complications After Lung Transplantation

Lung transplant prolongs life and improves quality of life in patients with end-stage lung disease. However, survival of lung transplant recipients is shorter compared to patients with other solid organ transplants, due to many unique features of the lung allograft. Patients can develop a multitude of noninfectious (e.g., primary graft dysfunction, pulmonary embolism, rejection, acute and chronic, renal insufficiency, malignancies) and infectious (i.e., bacterial, fungal, and viral) complications and require complex multidisciplinary care. This chapter discusses medical course and complications that patients might experience after lung transplantation.

Predictors of Long-Term Exercise Capacity in Patients Who Have Had Lung Transplantation

INTRODUCTION

Six-minute walk distance (6MWD) is a widely used surrogate for exercise capacity in patients both pre- and post-lung transplant. Multiple factors have been suggested to influence exercise capacity.

RESEARCH QUESTIONS

This study sought to determine the change in exercise capacity over time and factors that influence long-term exercise capacity.

DESIGN

Data were collected prospectively on lung transplant recipients from 1 center. The 6MWD was measured preoperatively and at the 6- and 12-month clinic visits postoperatively. The Enright equation was used to calculate patients' percentage predicted 6MWD. The change in 6MWD over time was calculated, and multiple factors affecting 6MWD were analyzed, including predictors of 6MWD at 6 and 12 months posttransplant.

RESULTS

Sixty lung transplant recipients were enrolled. Significant improvement in 6MWD was found between pretransplant and hospital discharge and between hospital discharge and 6 months posttransplant. The percentage predicted 6MWD improved significantly from pretransplant to 6 months and to 12 months posttransplant. Factors associated with 6MWD were sex, diagnosis, graft type, and age. Factors predicting long-term exercise capacity included 6MWD at referral, pretransplant, and hospital discharge; pulmonary diagnosis; and type of transplant.

CONCLUSION

The 6MWD provided useful information about patients' exercise capacity during phases of lung transplantation. The percentage predicted for each patient was found to be a more valuable measure than absolute 6MWD. Intensive, individualized training posttransplant is essential to optimize exercise capacity for this population.

High-Resolution CT Findings of Obstructive and Restrictive Phenotypes of Chronic Lung Allograft Dysfunction: More Than Just Bronchiolitis Obliterans Syndrome

OBJECTIVE

The purpose of this article is to review the high-resolution CT characteristics of individual obstructive and restrictive chronic lung allograft dysfunction (CLAD) phenotypes to aid in making accurate diagnoses and guiding treatment.

CONCLUSION

Long-term survival and function after lung transplant are considerably worse compared with after other organ transplants. CLAD is implicated as a major limiting factor for long-term graft viability. Historically thought to be a single entity, bronchiolitis obliterans syndrome, CLAD is actually a heterogeneous group of disorders with distinct subtypes.

Donor-Reactive Regulatory T Cell Frequency Increases During Acute Cellular Rejection of Lung Allografts

BACKGROUND

Acute cellular rejection is a major cause of morbidity after lung transplantation. Because regulatory T (Treg) cells limit rejection of solid organs, we hypothesized that donor-reactive Treg increase after transplantation with development of partial tolerance and decrease relative to conventional CD4 (Tconv) and CD8 T cells during acute cellular rejection.

METHODS

To test these hypotheses, we prospectively collected 177 peripheral blood mononuclear cell specimens from 39 lung transplant recipients at the time of transplantation and during bronchoscopic assessments for acute cellular rejection. We quantified the proportion of Treg, CD4 Tconv, and CD8 T cells proliferating in response to donor-derived, stimulated B cells. We used generalized estimating equation-adjusted regression to compare donor-reactive T cell frequencies with acute cellular rejection pathology.

RESULTS

An average of 16.5 ± 9.0% of pretransplantation peripheral blood mononuclear cell Treg cell were donor-reactive, compared with 3.8% ± 2.9% of CD4 Tconv and 3.4 ± 2.6% of CD8 T cells. These values were largely unchanged after transplantation. Donor-reactive CD4 Tconv and CD8 T cell frequencies both increased 1.5-fold (95% confidence interval [95% CI], 1.3-1.6; P < 0.001 and 95% CI, 1.2-1.6; P = 0.007, respectively) during grade A2 rejection compared with no rejection. Surprisingly, donor-reactive Treg frequencies increased by 1.7-fold (95% CI, 1.4-1.8; P < 0.001).

CONCLUSIONS

Contrary to prediction, overall proportions of donor-reactive Treg cells are similar before and after transplantation and increase during grade A2 rejection. This suggests how A2 rejection can be self-limiting. The observed increases over high baseline proportions in donor-reactive Treg were insufficient to prevent acute lung allograft rejection.

Current Nutrition Practices in Adult Lung Transplantation

Nutrition therapy is vital to the overall management of lung transplant recipients. The objective of this review is to outline the current applications of pre- and posttransplant nutrition management of the adult lung transplant recipient. Pretransplant nutrition therapy decisions are based on cause of end-stage lung disease, transplant indications, and pretransplant nutritional status. Maintaining adequate nutrient stores is the major goal of nutrition therapy for patients awaiting transplantation. In the posttransplant course, several gastrointestinal (GI) complications such as gastroesophageal reflux, gastroparesis, and distal intestinal obstruction syndrome complicate nutritional recovery. Long-term nutrition therapy for lung transplant recipients is aimed at management of common comorbid conditions such as obesity, diabetes mellitus, hypertension, osteoporosis, and hyperlipidemia. Lung transplantation outcomes are steadily improving; however, much has yet to be explored to improve the nutrition management of these patients in both the pre- and posttransplantation course.

Medical Weight Loss Treatment Options in Obese Solid-Organ Transplant Candidates

With the increasing incidence of obesity in our country, the rate of obesity seen in organ transplant candidates is also rising. Accurate descriptions and measures of weight and degree of obesity vary between organ systems. Weight loss can be achieved in some patients while they wait for the transplant surgery. Weight reduction in transplant candidates involves a team approach, with a program of education and support, including medical nutrition therapy, physical therapy, and psychological support. The safety and applicability of weight loss medications to assist with pretransplant weight loss is also not well understood. It is not yet well known if weight loss before transplantation will improve posttransplant outcomes. Many questions regarding the treatment of obesity in transplant candidates remain unanswered.

Sofosbuvir-based regimens for the treatment of hepatitis C virus in patients who underwent lung transplant: case series and review of the literature

BACKGROUND

Chronic infection with HCV can rapidly progress to cirrhosis leading to increased mortality rates in immunosuppressed organ-transplanted patients. In liver-transplanted patients, the introduction of directly acting antivirals has modified HCV natural history by providing a safe and effective therapy for this group of patients. To date there are no data on safety and efficacy of IFN-free regimens in HCV patients who received lung transplant (LuT).

METHODS

We report three patients who have received anti-HCV treatment after LuT with Sofosbuvir-based regimens.

RESULTS

All patients achieved a SVR, no unexpected safety signals were observed and no modifications in immunosuppressants were required.

CONCLUSIONS

Our report is the first to show that HCV patients who underwent LuT can be safely treated with IFN-free regimens, thus opening the door for refined clinical management of this category of patients.

Advance Care Planning after Lung Transplantation: A Case of Missed Opportunities

After lung transplantation, recipients are regularly evaluated by the transplant team and often require multiple hospitalizations. The primary focus of care during this time is on detecting and treating complications and may not necessarily include advance care planning discussions. This focus may leave clinicians unaware of the recipient's treatment preferences and place a burden on families trying to decide whether to undergo or forgo life-sustaining treatment when the recipient's medical condition deteriorates. We report the case of a woman with bronchiolitis obliterans who was admitted to the transplant center 37 times and died in the intensive care unit. Although progressive deterioration of her medical condition was well documented, her medical records revealed no evidence of advance care planning discussions with the patient and family. Incorporating timely advance care planning and integrating palliative care in the ongoing posttransplant clinical management may benefit patients, families, and clinicians as recipients approach the final stage of their illness.

The utility of preoperative six-minute-walk distance in lung transplantation

RATIONALE

The use of 6-minute-walk distance (6MWD) as an indicator of exercise capacity to predict postoperative survival in lung transplantation has not previously been well studied.

OBJECTIVES

To evaluate the association between 6MWD and postoperative survival following lung transplantation.

METHODS

Adult, first time, lung-only transplantations per the United Network for Organ Sharing database from May 2005 to December 2011 were analyzed. Kaplan-Meier methods and Cox proportional hazards modeling were used to determine the association between preoperative 6MWD and post-transplant survival after adjusting for potential confounders. A receiver operating characteristic curve was used to determine the 6MWD value that provided maximal separation in 1-year mortality. A subanalysis was performed to assess the association between 6MWD and post-transplant survival by disease category.

MEASUREMENTS AND MAIN RESULTS

A total of 9,526 patients were included for analysis. The median 6MWD was 787 ft (25th-75th percentiles = 450-1,082 ft). Increasing 6MWD was associated with significantly lower overall hazard of death (P < 0.001). Continuous increase in walk distance through 1,200-1,400 ft conferred an incremental survival advantage. Although 6MWD strongly correlated with survival, the impact of a single dichotomous value to predict outcomes was limited. All disease categories demonstrated significantly longer survival with increasing 6MWD (P ≤ 0.009) except pulmonary vascular disease (P = 0.74); however, the low volume in this category (n = 312; 3.3%) may limit the ability to detect an association.

CONCLUSIONS

6MWD is significantly associated with post-transplant survival and is best incorporated into transplant evaluations on a continuous basis given limited ability of a single, dichotomous value to predict outcomes.

An international ISHLT/ATS/ERS clinical practice guideline: diagnosis and management of bronchiolitis obliterans syndrome

Bronchiolitis obliterans syndrome (BOS) is a major complication of lung transplantation that is associated with poor survival. The International Society for Heart and Lung Transplantation, American Thoracic Society, and European Respiratory Society convened a committee of international experts to describe and/or provide recommendations for 1) the definition of BOS, 2) the risk factors for developing BOS, 3) the diagnosis of BOS, and 4) the management and prevention of BOS. A pragmatic evidence synthesis was performed to identify all unique citations related to BOS published from 1980 through to March, 2013. The expert committee discussed the available research evidence upon which the updated definition of BOS, identified risk factors and recommendations are based. The committee followed the GRADE (Grading of Recommendation, Assessment, Development and Evaluation) approach to develop specific clinical recommendations. The term BOS should be used to describe a delayed allograft dysfunction with persistent decline in forced expiratory volume in 1 s that is not caused by other known and potentially reversible causes of post-transplant loss of lung function. The committee formulated specific recommendations about the use of systemic corticosteroids, cyclosporine, tacrolimus, azithromycin and about re-transplantation in patients with suspected and confirmed BOS. The diagnosis of BOS requires the careful exclusion of other post-transplant complications that can cause delayed lung allograft dysfunction, and several risk factors have been identified that have a significant association with the onset of BOS. Currently available therapies have not been proven to result in significant benefit in the prevention or treatment of BOS. Adequately designed and executed randomised controlled trials that properly measure and report all patient-important outcomes are needed to identify optimal therapies for established BOS and effective strategies for its prevention.

Antifungal prophylaxis in pediatric lung transplantation: an international multicenter survey

Fungal infections create a significant risk to pediatric lung transplant recipients. However, no international consensus guidelines exist for fungal infection prevention strategies. It was the aim to describe the current strategies of antifungal prophylaxis in pediatric lung transplant centers. A self-administered, web-based survey on current practices to prevent fungal infection was circulated to centers within the IPLTC. Twenty-one (88%) IPLTC centers participated, predominantly from Europe and the US. More than 50% of respondents perform adult and pediatric lung transplant operations. Twenty-four percent use universal prophylaxis, 28% give prophylaxis to all patients but stratify the antifungal coverage based on pretransplant risk, and 48% target prophylaxis to only the children with CF or pretransplantation fungal colonization. Commonly, centers aim to target Aspergillus and Candida infection. Monotherapy with either voriconazole or inhaled amphotericin B is used in the majority of centers. Institutions utilize prophylactic therapy for variable time periods (40% 3-6 months; 30% ≥12 months). Alternative drugs were prescribed for lack of tolerance, toxicity, or positive surveillance culture. TDM (itraconazole/voriconazole) was used in 86% of centers. The survey revealed a wide range of antifungal prophylaxis strategies as current international practice in pediatric lung transplant recipients.

Nosocomial infections within the first month of solid organ transplantation

Infections remain a common complication of solid organ transplantation. Early postoperative infections remain a significant cause of morbidity and mortality in solid organ transplant (SOT) recipients. Although significant effort has been made to understand the epidemiology and risk factors for early nosocomial infections in other surgical populations, data in SOT recipients are limited. A literature review was performed to summarize the current understanding of pneumonia, urinary tract infection, surgical-site infection, bloodstream infection, and Clostridium difficult colitis, occurring within the first 30 days after transplantation.

Lung transplantation in patients with cystic fibrosis: special focus to infection and comorbidities

Despite advances in medical care, patients with cystic fibrosis still face limited life expectancy. The most common cause of death remains respiratory failure. End-stage cystic fibrosis can be treated with lung transplantation and is the third most common reason for which the procedure is performed. Outcomes for cystic fibrosis are better than most other lung diseases, but remain limited (5-year survival 60%). For patients with advanced disease lung transplantation appears to improve survival. Outcomes for patients with Burkholderia cepacia remain poor, although they are better for patients with certain genomovars. Controversy exists about Mycobacterium abscessus infection and appropriateness for transplant. More information is also becoming available for comorbidities, including diabetes and pulmonary hypertension among others. Extra-corporeal membrane oxygenation is used more frequently for end-stage disease as a bridge to lung transplantation and will likely be used more in the future.

Bronchiolitis obliterans syndrome: the Achilles' heel of lung transplantation

Lung transplantation is a therapeutic option for patients with end-stage pulmonary disorders. Unfortunately, chronic lung allograft dysfunction (CLAD), most commonly manifest as bronchiolitis obliterans syndrome (BOS), continues to be highly prevalent and is the major limitation to long-term survival. The pathogenesis of BOS is complex and involves alloimmune and nonalloimmune pathways. Clinically, BOS manifests as airway obstruction and dyspnea that are classically progressive and ultimately fatal; however, the course is highly variable, and distinguishable phenotypes may exist. There are few controlled studies assessing treatment efficacy, but only a minority of patients respond to current treatment modalities. Ultimately, preventive strategies may prove more effective at prolonging survival after lung transplantation, but their remains considerable debate and little data regarding the best strategies to prevent BOS. A better understanding of the risk factors and their relationship to the pathological mechanisms of chronic lung allograft rejection should lead to better pharmacological targets to prevent or treat this syndrome.

Losing ground: multidrug-resistant bacteria in solid-organ transplantation

PURPOSE OF REVIEW

Multidrug-resistant (MDR) bacteria can cause serious infections in solid-organ transplant recipients. This review focuses on the role of MDR bacteria in posttransplant infections.

RECENT FINDINGS

The incidence of MDR bacterial infections among solid-organ transplant recipients is increasing steadily. There is wide variability in the specific MDR bacteria causing infection based on the organ transplanted, geography, timing with respect to transplantation, and additional risk factors. Rarely these infections can be transmitted via the transplanted organ. Prompt recognition and early appropriate treatment of MDR bacterial infections are especially critical in this immunosuppressed population. In order to promptly initiate appropriate antimicrobial therapy for these organisms, high-risk patients should receive appropriate broad-spectrum antibiotics.

SUMMARY

MDR bacterial infections vary widely and require careful antibiotic selection to reduce mortality.

Prospective, observational study of voriconazole therapeutic drug monitoring among lung transplant recipients receiving prophylaxis: factors impacting levels of and associations between serum troughs, efficacy, and toxicity

Voriconazole prophylaxis is common following lung transplantation, but the value of therapeutic drug monitoring is unknown. A prospective, observational study of lung transplant recipients (n = 93) receiving voriconazole prophylaxis was performed. Serum voriconazole troughs (n = 331) were measured by high-pressure liquid chromatography. The median initial and subsequent troughs were 1.91 and 1.46 μg/ml, respectively. The age of the patient directly correlated with initial troughs (P = 0.005). Patients that were ≥ 60 years old and cystic fibrosis patients were significantly more likely to have higher and lower initial troughs, respectively. In 95% (88/93) of patients, ≥ 2 troughs were measured. In 28% (25/88) and 32% (28/88) of these patients, all troughs were ≤ 1.5 μg/ml or >1.5 μg/ml, respectively. Ten percent (10/93) and 27% (25/93) of the patients developed invasive fungal infection (tracheobronchitis) and fungal colonization, respectively. The median troughs at the times of positive and negative fungal cultures were 0.92 and 1.72 μg/ml (P = 0.07). Invasive fungal infections or colonization were more likely with troughs of ≤ 1.5 μg/ml (P = 0.01) and among patients with no trough of >1.5 μg/ml (P = 0.007). Other cutoff troughs correlated less strongly with microbiologic outcomes. Troughs correlated directly with aspartate transferase levels (P = 0.003), but not with other liver enzymes. Voriconazole was discontinued due to suspected toxicity in 27% (25/93) of the patients. The troughs did not differ at the times of suspected drug-induced hepatotoxicity, central nervous system (CNS) toxicity, or nausea/vomiting and in the absence of toxicity. Voriconazole prophylaxis was most effective at troughs of >1.5 μg/ml. A cutoff for toxicity was not identified, but troughs of >4 μg/ml were rare. The data support a target range of >1.5 to 4 μg/ml.

Spirometrically significant acute rejection increases the risk for BOS and death after lung transplantation

Acute rejection (AR) is a common complication following lung transplantation and is an established risk factor for bronchiolitis obliterans syndrome (BOS). AR clinical presentation varies considerably and is sometimes associated with an acute decrease in forced expiratory volume in 1 s (FEV1). We hypothesized that lung transplant recipients who experience such spirometrically significant AR (SSAR), as defined by a ≥10% decline in FEV1 relative to the prior pulmonary function test, are subsequently at increased risk for BOS and worse overall survival. In a large single center cohort (n = 339), SSAR occurred in 79 subjects (23%) and significantly increased the risk for BOS (p < 0.0001, HR = 3.2, 95% CI 2.3-4.6) and death (p = 0.0001, HR = 2.3, 95% CI 1.5-3.5). These effects persisted after multivariate adjustment for pre-BOS AR and lymphocytic bronchiolitis burden. An analysis of the subset of patients who experienced severe SSAR (≥20% decline in FEV1) resulted in even greater hazards for BOS and death. Thus, we demonstrate a novel physiological measure that allows discrimination of patients at increased risk for worse posttransplant outcomes. Further studies are needed to determine mechanisms of airflow impairment and whether aggressive clinical interventions could improve post-SSAR outcomes.

Lung transplantation in autoimmune diseases

In the last 45 years, lung transplantation has evolved from its status as a rare extreme form of surgical therapy for the treatment of advanced lung diseases to an accepted therapeutic option for select patients. Although pulmonary fibrosis and pulmonary vascular diseases are important indications for lung transplantation, only a small percentage of transplants are performed in patients with collagen vascular diseases. The reasons for this low number are multifactorial. This article reviews issues relevant to all lung transplant candidates and recipients as well as those specific to patients with autoimmune diseases.

Antifungal prophylaxis in lung transplantation--a world-wide survey

While variations in antifungal prophylaxis have been previously reported in lung transplant (LTx) recipients, recent clinical practice is unknown. Our aim was to determine current antifungal prophylactic practice in LTx centers world-wide. One nominated LTx clinician from each active center was invited by e-mail to participate in a web-based survey between September 2009 and January 2010. Fifty-seven percent (58/102) responded. The majority of responses were from medical directors of LTx centers (72.4%), and from the United States (44.8%). Within the first 6 months post-LTx, most centers (58.6%) employed universal prophylaxis, with 97.1% targeting Aspergillus species. Voriconazole alone, and in combination with inhaled amphotericin B (AmB), were the preferred first-line agents. Intolerance to side effects of voriconazole (69.2%) was the main reason for switching to alternatives. Beyond 6 months post-LTx, most (51.8%) did not employ antifungal prophylaxis. Fifteen centers (26.0%) conducted routine antifungal therapeutic drug monitoring during prophylactic period. There are differences in strategies employed between U.S. and European centers. Most respondents indicated a need for antifungal prophylactic guidelines. In comparison to earlier findings, there was a major shift toward prophylaxis with voriconazole and an increased use of echinocandins, posaconazole and inhaled lipid formulation AmB.

Workshop on idiopathic pulmonary fibrosis in older adults

Idiopathic pulmonary fibrosis (IPF), a heterogeneous disease with respect to clinical presentation and rates of progression, disproportionately affects older adults. The diagnosis of IPF is descriptive, based on clinical, radiologic, and histopathologic examination, and definitive diagnosis is hampered by poor interobserver agreement and lack of a consensus definition. There are no effective treatments. Cellular, molecular, genetic, and environmental risk factors have been identified for IPF, but the initiating event and the characteristics of preclinical stages are not known. IPF is predominantly a disease of older adults, and the processes underlying normal aging might significantly influence the development of IPF. Yet, the biology of aging and the principles of medical care for this population have been typically ignored in basic, translational, or clinical IPF research. In August 2009, the Association of Specialty Professors, in collaboration with the American College of Chest Physicians, the American Geriatrics Society, the National Institute on Aging, and the National Heart, Lung, and Blood Institute, held a workshop, summarized herein, to review what is known, to identify research gaps at the interface of aging and IPF, and to suggest priority areas for future research. Efforts to answer the questions identified will require the integration of geriatrics, gerontology, and pulmonary research, but these efforts have great potential to improve care for patients with IPF.

Optimizing post-transplant outcomes in lung transplantation

Lung transplant recipients are at risk of numerous complications, which range from early events, such as primary graft dysfunction, to late events, including opportunistic infection or graft loss caused by chronic rejection. Although lung transplantation is often the only therapeutic option that can improve quality of life and prolong survival for many forms of end-stage lung disease, survival following lung transplantation is significantly worse than survival following transplantation of other solid organs. Carefully choosing potential recipients for listing, maximizing the likelihood that donor organs will function well following implantation, appropriate use of immunosuppressive agents to prevent allograft rejection, prophylactic or pre-emptive strategies to prevent allograft infection and appropriate surveillance to detect significant complications are key to maximizing the likelihood of prolonged graft and patient survival while avoiding significant complications following lung transplantation. Post-transplant outcomes will be optimized by a team approach to comprehensive management of the lung transplantation recipient combined with vigilant surveillance to detect complications in a timely fashion.