Hyperacute rejection of a pulmonary allograft. Immediate clinical and pathologic findings

The clinical utility and thresholds of Virtual and Halifaster Flow crossmatches in lung transplantation

INTRODUCTION

Immune sensitization, defined as the presence of alloreactive donor-specific antibodies (DSA), is associated with increased wait-times and inferior transplant outcomes. Identifying pre-transplant DSA with a physical cell-based assay is critical in defining immunological risk. However, improved solid phase antibody detection has provided the potential to forgo this physical assay. Here, we evaluated the association between DSA mean fluorescence intensity (MFI) and the recently introduced Halifaster Flow cytometry crossmatch (FXM) to determine if MFI could predict the outcome of FXM and whether a virtual crossmatch (VXM) would provide an accurate risk assessment.

METHODS

Sera from 134 waitlisted lung patients was retrospectively assessed by Halifaster FXM against lymphocytes preparations from 32 donors, resulting in 265 FXMs. HLA typing was performed to 2-field allelic level and Luminex single antigen beads (SAB) used to identify DSA. The association between FXM and Luminex MFI was calculated using ROC analysis. MFI threshold accuracy was confirmed using a separate validation cohort (174 recipient sera and 34 donors), whereby both virtual crossmatch (VXM) and FXMs were compared.

RESULTS

From the 265 FXM performed, 48 (18%) T-cell (TFXM) and 56 (21%) B-cell (BFXM) were positive. In the evaluation cohort, MFI thresholds of 2000 for HLA-A, B, DRB1 and >4000 for DQB1, were predictive of a positive FXM. The validation cohort of 233 paired FXM and VXM confirmed these MFI thresholds for both TFXM and BFXM with an accuracy of 91.4% and 89.3% respectively.

CONCLUSION

A positive VXM, defined with HLA-specific MFI thresholds predicts Halifaster FXM reactivity, and can potentially expedite organ allocation, by minimising the need for the more time-consuming flow cytometry crossmatch. This article is protected by copyright. All rights reserved.

Complications of Lung Transplantation: Update on Imaging Manifestations and Management

As lung transplantation has become the most effective definitive treatment option for end-stage chronic respiratory diseases, yearly rates of this surgery have been steadily increasing. Despite improvement in surgical techniques and medical management of transplant recipients, complications from lung transplantation are a major cause of morbidity and mortality. Some of these complications can be classified on the basis of the time they typically occur after lung transplantation, while others may occur at any time. Imaging studies, in conjunction with clinical and laboratory evaluation, are key components in diagnosing and monitoring these conditions. Therefore, radiologists play a critical role in recognizing and communicating findings suggestive of lung transplantation complications. A description of imaging features of the most common lung transplantation complications, including surgical, medical, immunologic, and infectious complications, as well as an update on their management, will be reviewed here. Keywords: Pulmonary, Thorax, Surgery, Transplantation Supplemental material is available for this article. © RSNA, 2021.

Imaging indications and findings in evaluation of lung transplant graft dysfunction and rejection

Lung transplantation is a treatment option in end-stage lung disease. Complications can develop along a continuum in the immediate or longer post-transplant period, including surgical and technical complications, primary graft dysfunction, rejection, infections, post-transplant lymphoproliferative disorder, and recurrence of the primary disease. These complications have overlapping clinical and imaging features and often co-exist. Time of onset after transplant is helpful in narrowing the differential diagnosis. In the early post transplantation period, imaging findings are non-specific and need to be interpreted in the context of the clinical picture and other investigations. In contrast, imaging plays a key role in diagnosing and monitoring patients with chronic lung allograft dysfunction. The goal of this article is to review primary graft dysfunction, acute rejection, and chronic rejection with emphasis on the role of imaging, pathology findings, and differential diagnosis.

Human leukocyte antigens antibodies after lung transplantation: Primary results of the HALT study

Donor-specific antibodies (DSA) to mismatched human leukocyte antigens (HLA) are associated with worse outcomes after lung transplantation. To determine the incidence and characteristics of DSA early after lung transplantation, we conducted a prospective multicenter observational study that used standardized treatment and testing protocols. Among 119 transplant recipients, 43 (36%) developed DSA: 6 (14%) developed DSA only to class I HLA, 23 (53%) developed DSA only to class II HLA, and 14 (33%) developed DSA to both class I and class II HLA. The median DSA mean fluorescence intensity (MFI) was 3197. We identified a significant association between the Lung Allocation Score and the development of DSA (HR = 1.02, 95% CI: 1.001-1.03, P = .047) and a significant association between DSA with an MFI ≥ 3000 and acute cellular rejection (ACR) grade ≥ A2 (HR = 2.11, 95% CI: 1.04-4.27, P = .039). However, we did not detect an association between DSA and survival. We conclude that DSA occur frequently early after lung transplantation, and most target class II HLA. DSA with an MFI ≥ 3000 have a significant association with ACR. Extended follow-up is necessary to determine the impact of DSA on other important outcomes.

Pathology of Lung Rejection: Cellular and Humoral Mediated

Acute rejection is an important risk factor for bronchiolitis obliterans syndrome, the clinical manifestation of chronic airway rejection in lung allograft recipients. Patients with acute rejection might be asymptomatic or present with symptoms that are not specific and can be also seen in other conditions. Clinical tests such as pulmonary function tests and imaging studies among others usually are abnormal; however, their results are also not specific for acute rejection. Histopathologic features of acute rejection in adequate samples of transbronchial lung biopsy of the lung allograft are currently the gold standard to assess for acute rejection in lung transplant recipients. Acute alloreactive injury can affect both the vasculature and the airways. Currently, the guidelines of the 2007 International Society of Heart and Lung Transplantation consensus conference are recommended for the histopathologic assessment of rejection. There are no specific morphologic features recognized to diagnose antibody-mediated rejection (AMR) in lung allografts. Therefore, the diagnosis of AMR currently requires a “triple test” including clinical features, serologic evidence of donor-specific antibodies, and pathologic findings supportive of AMR. Complement 4d deposition is used to support a diagnosis of AMR in many solid organ transplants; however, its significance for the diagnosis of AMR in lung allografts is not entirely clear. This chapter discusses the currently recommended guidelines for the assessment of cellular rejection of lung allografts and summarizes our knowledge about morphologic features and immunophenotypic tests that might help in the diagnosis of AMR.

Pre-transplant Panel Reactive Antibody and Survival in Adult Cystic Fibrosis Patients After Lung Transplantation

BACKGROUND

Survival implications of pre-transplant antibodies to human leukocyte antigens prior to lung transplantation (LTx) in adult cystic fibrosis (CF) patients are unknown.

METHODS

Data from the United Network for Organ Sharing Registry (1987-2013) were used to compare survival differences in adult CF patients with pre-transplant class I and II panel reactive antibody (PRA) levels ≤10 versus >10 %.

RESULTS

Of 3149 CF LTx recipients, 1526 and 1399 were included in univariate survival analyses of class I and II PRA, respectively, while 1106 and 1001 were included in multivariate Cox analyses for class I and class II, respectively. Kaplan-Meier survival functions failed to demonstrate significant differences in survival with PRA >10 % for class I (Log-rank test: χ (2) (df = 1): 1.11, p = 0.293) or class II (Log-rank test: χ (2) (df = 1): 0.99, p = 0.320). Adjusting for covariates, multivariate Cox models demonstrated that class II PRA >10 % was associated with a significant increase in mortality hazard (HR 1.918; 95 % CI 1.128, 3.261; p = 0.016), whereas class I PRA >10 % was uncorrelated with this outcome.

CONCLUSIONS

Pre-transplant PRA class II >10 % in adult CF patients is associated with elevated mortality hazard after LTx.

Lung Transplantation

The therapeutic options for patients with advanced pulmonary parenchymal or vascular disorders are currently limited. Lung transplantation remains one of the few viable interventions, but on account of the insufficient donor pool only a minority of these patients actually undergo the procedure each year. Following transplantation there are a number of early and late allograft complications such as primary graft dysfunction, allograft rejection, infection, post-transplant lymphoproliferative disorder and late injury that is now classified as chronic lung allograft dysfunction. The pathologist plays an essential role in the diagnosis and classification of these myriad complications. Although the transplant procedures are performed in selected centers patients typically return to their local centers. When complications arise it is often the responsibility of the local pathologist to evaluate specimens. Therefore familiarity with the pathology of lung transplantation is important.

Antibody-mediated Rejection in Lung Transplantation

There has been increasing awareness of antibody-mediated rejection (AMR) as an important cause of graft failure after lung transplantation in recent years. However, the diagnostic criteria for pulmonary AMR are not well defined. All four tenets of AMR in kidney and heart transplantation, graft dysfunction, complement component deposition, circulating donor-specific antibodies (DSA), and histopathologic changes consistent with AMR, are infrequently present in lung transplantation. Nonetheless, the lung transplant community has made important progress recognizing cases of AMR and developing a definition. However, AMR is often refractory to therapy resulting in graft failure and death. In this review, we discuss the progress and challenges in the diagnosis and therapeutic options for pulmonary AMR. In addition, we briefly examine emerging paradigms of C4d-negative AMR and chronic AMR, and conclude that significant progress is needed to mitigate the effects of humoral immune responses after lung transplantation.

Antibody desensitization therapy in highly sensitized lung transplant candidates

As HLAs antibody detection technology has evolved, there is now detailed HLA antibody information available on prospective transplant recipients. Determining single antigen antibody specificity allows for a calculated panel reactive antibodies (cPRA) value, providing an estimate of the effective donor pool. For broadly sensitized lung transplant candidates (cPRA ≥ 80%), our center adopted a pretransplant multi-modal desensitization protocol in an effort to decrease the cPRA and expand the donor pool. This desensitization protocol included plasmapheresis, solumedrol, bortezomib and rituximab given in combination over 19 days followed by intravenous immunoglobulin. Eight of 18 candidates completed therapy with the primary reasons for early discontinuation being transplant (by avoiding unacceptable antigens) or thrombocytopenia. In a mixed-model analysis, there were no significant changes in PRA or cPRA changes over time with the protocol. A sub-analysis of the median fluorescence intensity (MFI) change indicated a small decline that was significant in antibodies with MFI 5000-10,000. Nine of 18 candidates subsequently had a transplant. Posttransplant survival in these nine recipients was comparable to other pretransplant-sensitized recipients who did not receive therapy. In summary, an aggressive multi-modal desensitization protocol does not significantly reduce pretransplant HLA antibodies in a broadly sensitized lung transplant candidate cohort.

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.

Ectonucleotidases in solid organ and allogeneic hematopoietic cell transplantation

Extracellular nucleotides are ubiquitous signalling molecules which modulate distinct physiological and pathological processes. Nucleotide concentrations in the extracellular space are strictly regulated by cell surface enzymes, called ectonucleotidases, which hydrolyze nucleotides to the respective nucleosides. Recent studies suggest that ectonucleotidases play a significant role in inflammation by adjusting the balance between ATP, a widely distributed proinflammatory danger signal, and the anti-inflammatory mediator adenosine. There is increasing evidence for a central role of adenosine in alloantigen-mediated diseases such as solid organ graft rejection and acute graft-versus-host disease (GvHD). Solid organ and hematopoietic cell transplantation are established treatment modalities for a broad spectrum of benign and malignant diseases. Immunological complications based on the recognition of nonself-antigens between donor and recipient like transplant rejection and GvHD are still major challenges which limit the long-term success of transplantation. Studies in the past two decades indicate that purinergic signalling influences the severity of alloimmune responses. This paper focuses on the impact of ectonucleotidases, in particular, NTPDase1/CD39 and ecto-5'-nucleotidase/CD73, on allograft rejection, acute GvHD, and graft-versus-leukemia effect, and on possible clinical implications for the modulation of purinergic signalling after transplantation.

Antibody-Mediated Lung Transplant Rejection

Antibody-mediated rejection after lung transplantation remains enigmatic. However, emerging evidence over the past several years suggests that humoral immunity plays an important role in allograft rejection. Indeed, the development of donor-specific antibodies after transplantation has been identified as an independent risk factor for acute cellular rejection and bronchiolitis obliterans syndrome. Furthermore, cases of acute antibody-mediated rejection resulting in severe allograft dysfunction have been reported, and these demonstrate that antibodies can directly injure the allograft. However, the incidence and toll of antibody-mediated rejection are unknown because there is no widely accepted definition and some cases may be unrecognized. Clearly, humoral immunity has become an important area for research and clinical investigation.

Critical care management of the lung transplant recipient

Lung transplantation provides the prospect of improved survival and quality of life for patients with end stage lung and pulmonary vascular diseases. Given the severity of illness of such patients at the time of surgery, lung transplant recipients require particular attention in the immediate post-operative period to ensure optimal short-term and long-term outcomes. The management of such patients involves active involvement of a multidisciplinary team versed in common post-operative complications. This review provides an overview of such complications as they pertain to the practitioners caring for post-operative lung transplant recipients. Causes and treatment of conditions affecting early morbidity and mortality in lung transplant recipients will be detailed, including primary graft dysfunction, cardiovascular and surgical complications, and immunologic and infectious issues. Additionally, lung donor management issues and bridging the critically ill potential lung transplant recipient to transplantation will be discussed.

Fulminant hyperacute rejection after unilateral lung transplantation

Hyperacute rejection (HAR) is a well-known complication in renal and cardiac transplantation, but rare in lung recipients. We present a case of HAR of the lung graft with a fatal outcome of a male patient with preformed class II anti-HLA antibodies.

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.

Lung

Experiments with animals in the 1940 and 1950s demonstrated that lung transplantation was technically possible [33]. In 1963, Dr. James Hardy performed the first human lung transplantation. The recipient survived 18 days, ultimately succumbing to renal failure and malnutrition [58]. From 1963 through 1978, multiple attempts at lung transplantation failed because of rejection and complications at the bronchial anastomosis. In the 1980s, improvements in immunosuppression, especially the introduction of cyclosporin A, and enhanced surgical techniques led to renewed interest in organ transplantation. In 1981, a 45-year-old-woman received the first successful heart–lung transplantation for idiopathic pulmonary arterial hypertension (IPAH) [106]. She survived 5 years after the procedure. Two years later the first successful single lung transplantation for idiopathic pulmonary fibrosis (IPF) [128] was reported, and in 1986 the first double lung transplantation for emphysema [25] was performed.

Pathology of lung transplantation

The International Society for Heart and Lung Transplantation has a standardized nomenclature for the evaluation of lung allografts. Rejection of the lung allograft is divided into acute and chronic forms. Acute cellular rejection is characterized by perivascular accumulations of mononuclear cells and eosinophils; bronchiolar inflammation is also included in the grading scheme. Acute antibody-mediated rejection in lung allografts is not well defined. Chronic rejection is manifest by fibrous scarring narrowing the lumen of bronchioles, arteries, and veins. The diagnosis of rejection requires the exclusion of infection and other pathology in the allograft.

Hyperacute Rejection After Lung Transplantation Caused by Undetected Low-titer Anti-HLA Antibodies

Hyperacute rejection is an early complication of transplantation, caused by the presence in the recipient of pre-formed donor-directed antibodies (Ab). We report a case of fatal early graft dysfunction after lung transplantation in a female recipient with no anti-HLA Ab detected before transplantation. Further immunologic studies revealed the presence, in the pre-transplant serum, of low-titer anti-HLA Ab directed against the donor's HLA, detectable only by flow-cytometry screening for panel-reactive antibodies. This observation emphasizes the importance of sensitive Ab detection in patients awaiting lung transplantation. Women should be specifically targeted for such sensitive Ab detection.

Emerging drugs in lung transplantation

The balance between immunosuppression to ensure graft tolerance while preventing emergence of infectious complications is key in lung transplantation. Although opportunistic infection may appear to be the most important of these complications, malignancies and severe drug toxicities significantly affect the short- and long-term outcomes of the patients. The present practice is combination therapy using drugs with complementary immunosuppressive action, to achieve synergistic immunosuppression with the lowest possible toxicity. Components of immunosuppression include induction and maintenance regimens. Primary graft failure remains an important cause of mortality and morbidity in the immediate post-transplant period. Acute rejection is a common complication after lung transplant, but responds well to augmented immunosuppression and immunomodulation. Chronic rejection still is the major cause of mortality in patients who survive the initial year post-transplantation. Several new drugs have shown promise in decreasing the rate of loss of graft function. This review discusses the current and emerging therapeutic regimens.

Allograft Rejection After Lung Transplantation

Lung transplantation has become an accepted therapy for selected patients with advanced lung disease. One of the main limitations to successful lung transplantation is rejection of the transplanted organ. This article discusses the clinical presentation, treatment, and prevention of hyperacute, acute, and chronic rejection in the lung transplant recipient.

Utility of Peritransplant and Rescue Intravenous Immunoglobulin and Extracorporeal Immunoadsorption in Lung Transplant Recipients Sensitized to HLA Antigens

The role of anti-human leukocyte antigen (HLA) antibodies in lung transplantation is not fully clear. The presence of pretransplant third-party anti-HLA antibodies or the development of de novo anti-HLA antibodies has been associated with acute posttransplant complications, bronchiolitis obliterans syndrome (BOS), and early mortality in some studies. However, little has been reported regarding the utility of desensitization therapy in sensitized lung transplant recipients. For approximately 3 years, desensitization therapy consisting of intravenous immunoglobulin (IVIG) and, in most instances, extracorporeal immunoadsorption (ECI) has been administered peritransplant to lung transplant recipients at our institution with third-party anti-HLA antibodies or as rescue therapy to those who develop de novo anti-HLA antibodies. Notably, the administration of peritransplant desensitization therapy to these patients has been associated with improvement in several clinical parameters, including acute rejection and BOS. Furthermore, administration of rescue IVIG with or without ECI has been associated with an overall improvement in the rate of pulmonary function decline. Our experience suggests that desensitization therapy may be beneficial for lung transplant recipients with pretransplant or de novo anti-HLA antibodies. We discuss the appropriateness and clinical impact of IVIG and ECI in sensitized lung transplant recipients as well as cellular mechanisms that may contribute.

HLA-Specific antibodies are associated with high-grade and persistent-recurrent lung allograft acute rejection

BACKGROUND

The impact of HLA-specific antibodies is not well established in the acute rejection of lung allografts. Acute rejection represents the most important risk factor for the development of chronic lung allograft dysfunction.

METHODS

We analyzed the pattern of HLA antibodies before and after transplantation in 54 patients, and correlated our data with the presence and frequency of high-grade and persistent-recurrent acute rejection, during the first 18 post-operative months. The diagnosis of acute rejection was based on histologic International Society for Heart and Lung Transplantation (ISHLT)-published criteria.

RESULTS

Ten of 54 patients had a positive enzyme-linked immunoassay (ELISA) post-transplantation. In 90% of ELISA-positive patients, the presence of HLA antibodies was associated with persistent-recurrent acute rejections, compared with 34% in the ELISA-negative group (p < 0.005). There were 28 high-grade acute rejection episodes in the ELISA-positive group, compared with 36 in the ELISA-negative group (p < 0.0001). The ELISA-positive patients required a greater intensity of immunosuppressive therapy. The patients with ELISA-detected anti-HLA antibodies were at least 3-fold more likely to develop high-grade acute rejection and persistent-recurrent acute rejection, and 7-fold more likely to develop multiple episodes of persistent-recurrent acute rejection, compared with ELISA-negative patients.

CONCLUSIONS

ELISA-based screening for the development of HLA antibodies is a reliable method that can identify lung transplant recipients at increased risk for high-grade and persistent-recurrent acute rejection. Although bronchiolitis obliterans appears as a point of no return in the evolution of lung-transplanted patients, early detection of risk factors for acute rejection could indirectly decrease the incidence of bronchiolitis obliterans. These lung-transplanted patients may benefit from an altered strategy of immunosuppression.

Acute humoral rejection of human lung allografts and elevation of C4d in bronchoalveolar lavage fluid

Antibody-mediated rejection is well established for renal allografts but remains controversial for lung allografts. Cardinal features of antibody-mediated rejection in renal allografts include antibodies to donor human leukocyte antigen (HLA) and evidence for antibody action, such as complement activation demonstrated by C4d deposition. We report a lung allograft recipient with circulating antibodies to donor HLA who failed treatment for acute cellular rejection but responded to therapy for humoral rejection. To address the second criteria for antibody-mediated rejection, we determined whether complement activation could be detected by measuring C4d in bronchoalveolar lavage fluid (BALF) by ELISA. Airway allergen challenge of asthmatics activates the complement pathway; therefore, we used BALF from asthmatics pre- and post-allergen challenge to measure C4d. These controls demonstrated that ELISA could detect increases in C4d after allergen challenge. BALF from the index patient had elevated C4d concomitant with graft dysfunction and anti-donor HLA in the absence of infection. Analysis of BALF from 25 additional lung allograft recipients showed that C4d concentrations >100 ng/mL were correlated with anti-HLA antibodies (p = 0.006), but were also observed with infection and in asyptomatic patients. The findings support the occurrence of anti-HLA-mediated lung allograft rejection and suggest that C4d measurement in BALF may be useful in diagnosis.

National conference to assess antibody-mediated rejection in solid organ transplantation

The process of humoral rejection is multifaceted and has different manifestations in the various types of organ transplants. Because this process is emerging as a leading cause of graft loss, a conference was held in April 2003 to comprehensively address issues regarding humoral rejection. Though humoral rejection may result from different factors, discussion focused on a paradigm caused by antibodies, typically against donor HLA antigens, leading to the term 'antibody-mediated rejection' (AMR). Conference deliberations were separated into four workgroups: The Profiling Workgroup evaluated strengths and limitations of different methods for detecting HLA reactive antibody, and created risk assessment guidelines for AMR; The Diagnosis Workgroup reviewed clinical, pathologic, and serologic criteria for assessing AMR in renal, heart and lung transplant recipients; The Treatment Workgroup discussed advantages, limitations and possible mechanisms of action for desensitization protocols that may reverse AMR; and The Basic Science Workgroup presented animal and human immunologic models for humoral rejection and proposed potential targets for future intervention. This work represents a comprehensive review with contributions from experts in the fields of Transplantation Surgery, Medicine, Pathology, Histocompatibility, Immunology, and clinical trial design. Immunologic barriers once considered insurmountable are now consistently overcome to enable more patients to undergo organ transplantation.

Anti-HLA antibody analysis and crossmatching in heart and lung transplantation

Although the clinical significance of anti-HLA antibodies in heart and lung transplantation is less well studied than in renal transplantation, several studies have shown that heart and lung recipients transplanted in the presence of donor-specific antibodies are at increased risk for early acute rejection and have a lower graft survival. In an effort to avoid any increase in organ ischemia time, heart and lung candidates with anti-HLA antibodies have to be identified prior to transplantation and crossmatches performed with donor materials obtained prior to organ recovery. Both class I and II antibodies have been found to be associated with chronic rejection, defined in heart transplantation as transplant-related coronary artery disease (TRCAV) and in lung transplantation as obliterative bronchiolitis (OB) or bronchiolitis obliterative syndrome (BOS). Post-transplant de novo development of donor antigen-specific class II antibodies has been found to be especially deleterious, significantly increasing the risk of chronic rejection and poor graft outcome. Based on the review of studies regarding the development of anti-HLA antibodies and thoracic organ allograft rejection several conclusions can be drawn. The presence of class I and II-directed anti-HLA antibodies, detected by any method, are associated with acute and chronic rejection in heart and lung transplantation. Different therapeutic strategies have been used pre-transplantation to decrease the level of anti-HLA antibodies and post-transplantation to maintain low antibody levels or treat rejection, thereby improving graft outcome. Thus, monitoring the presence and the level of anti-HLA antibodies is prognostic of graft outcome and allows for measurement of therapeutic efficacy.

Critical care aspects of lung transplantation

Lung transplantation currently is the preferred treatment option for a variety of end-stage pulmonary diseases. Remarkable progress has occurred through refinements in technique and improved understanding of transplant immunology and microbiology. As a result, recipients are surviving longer after their transplant. Despite improvements in short- and intermediate-term survival, long-term success with lung transplantation remains limited by chronic allograft rejection, also known as bronchiolitis obliterans syndrome. Despite its long-term limitations, lung transplantation remains the only hope for many with end-stage pulmonary disease, and during the past 20 years, it has become increasingly accepted and used. As a result, clinicians working in an intensive care unit (ICU) are more likely to be exposed to these patients both in the immediate postoperative period as well as throughout their remaining lives. It is thus important that the ICU team have a working knowledge of the common complications, when these complications are most likely to occur, and how best to treat them when they do arise. The main focus of this review is to address the variety of potential graft and life-threatening problems that may occur in lung transplant recipients. Because the ICU is also the most common setting where a potential donor is identified, donor issues will briefly be addressed.

Perioperative care of the lung transplant patient

Improvements in the perioperative management of lung transplant recipients have produced a 90% survival in the first 30 days following surgery. Detailed attention to donor organ procurement and preservation of the allograft are important in ensuring an early successful outcome. Early antibacterial administration based on donor or pretransplant cultures and antiviral therapy in CMV-negative recipients assist in avoiding early infectious complications. Development of hypoxemia or hemodynamic instability in the perioperative period requires a rapid, systematic evaluation with attention to mechanical, immunologic, or infectious causes. Nonpulmonary complications are not infrequent in lung transplant recipients.

Analysis of early deaths after isolated lung transplantation

STUDY OBJECTIVES

To determine the causes of death in patients dying within 30 days after lung transplantation at the University of Florida, to assess the importance of several diagnostic modalities for determining the causes of their decline, and to construct an algorithm for the evaluation of patients with severe respiratory compromise occurring early after lung transplantation.

DESIGN

Retrospective review of medical records and pathology slides from all patients dying within 30 days after lung transplantation, and biopsy specimen diagnoses from all lung allograft recipients at the University of Florida.

PATIENTS

Nine deaths occurred during the first 30 days after transplantation among 117 patients undergoing 123 isolated lung transplantation operations.

RESULTS

Infections accounted for the greatest number of deaths (bacterial pneumonia, four patients; catheter-related bacteremia, one patient). Persistent pneumonia confirmed by biopsy specimen was usually accompanied by histologic manifestations of acute cellular rejection and was associated with poor patient outcome (ie, death or subsequent development of bronchiolitis obliterans syndrome). In two patients, antibody-mediated rejection either was the immediate cause of death (hyperacute rejection, one patient) or preceded a fatal case of pneumonia (accelerated antibody-mediated rejection, one patient). Other causes of death included hypoxic-ischemic encephalopathy secondary to an intraoperative cardiac arrest (one patient), pulmonary venous thrombosis with bacterial colonization of the thrombotic material (one patient), and ischemic reperfusion injury (one patient). In most patients, more than one type of diagnostic technique was needed to ascertain the cause of the catastrophic decline.

CONCLUSIONS

The causes of early posttransplant death in our patient group included infections, antibody-mediated rejection, hypoxic-ischemic encephalopathy secondary to cardiac arrest, pulmonary venous thrombosis, and ischemic reperfusion injury. Because these processes often demonstrate overlapping clinical and morphologic features requiring multiple diagnostic techniques for resolution, a systematic multimodality approach to diagnosis is advantageous for determining the causes of decline in individual patients and for estimating the incidences of the different causes of early graft and patient loss in the lung transplant population.

Lung transplantation at the turn of the century

Lung transplantation has become a viable treatment option for patients with end-stage lung disease. Donor selection and organ allocation must follow specific guidelines. Single, bilateral, and living-donor lobar transplantation have all been performed successfully for a variety of diseases. Complications include reimplantation response and airway complications. Rejection may occur in the hyperacute, acute, or chronic settings and requires judicious management with immunosuppression. Infection and malignancy remain potential complications of the commitment to lifelong systemic immunosuppression. Survival statistics have remained encouraging and continue to improve with experience. Improved exercise tolerance and quality of life have been demonstrated in the years following transplantation. Remaining obstacles include limited donor organ availability, long-term graft function, and patient survival. However, ongoing advances in immune tolerance and standardized training of physicians in the care of transplant patients should carry lung transplant forward in the twenty-first century.

Hyperacute rejection in single lung transplantation--case report of successful management by means of plasmapheresis and antithymocyte globulin treatment

We describe the third case and first successful treatment of hyperacute rejection in a pulmonary allograft recipient and detail the immediate clinical findings. The patient underwent single right lung transplantation for severe emphysema and chronic obstructive pulmonary disease. Three hours after completion of the vascular anatomoses oxygen desaturation and increased airway pressure was noted in combination with graft edema, frothy, pink fluid draining from the bronchial orifice, hemodynamic instability, thrombocytopenia, and coagulopathy. The retrospective cross-match result was reported to be positive. The clinical diagnosis of hyperacute rejection was made. A donor-specific IgG HLA antibody to A2 was identified. The standard immune suppression regimen was immediately modified and a hyperacute rejection protocol applied including plasmapheresis and antithymocyte globulin treatment as well as cyclophosphamide to decrease antibody existence and production. A remarkable clinical recovery was observed after the fifth postoperative day and completion of plasmapheresis when a repeated retrospective cross-match showed significantly decreasing anti-donor reactivity.