The two forms of bronchiolitis obliterans in heart-lung transplant recipients

Small Airway Disease: A Step Closer to Etiology-Based Classification of Bronchiolitis

Three major histologic patterns of bronchiolitis: obliterative bronchiolitis, follicular bronchiolitis, and diffuse panbronchiolitis, are reviewed in detail. These distinct patterns of primary bronchiolar injury provide a useful starting point for formulating a differential diagnosis and considering possible causes. In support of the aim toward a cause-based classification system of small airway disease, a simple diagnostic algorithm is provided for further subclassification of the above 3 bronchiolitis patterns according to the major associated etiologic subgroups.

Chronic lung allograft dysfunction: evolving practice

PURPOSE OF REVIEW

Chronic lung allograft dysfunction (CLAD) was recently introduced as an overarching term covering different phenotypes of chronic allograft dysfunction, including obstructive CLAD (bronchiolitis obliterans syndrome), restrictive CLAD (restrictive allograft syndrome) and graft dysfunction due to causes not related to chronic rejection. In the present review, we will highlight the latest insights and current controversies regarding the new CLAD terminology, underlying pathophysiologic mechanisms, diagnostic approach and possible treatment options.

RECENT FINDINGS

Different pathophysiological mechanisms are clearly involved in clinically distinct phenotypes of chronic rejection, as is reflected by differences in histology, allograft function and imaging. Therefore, not all CLAD patients may equally benefit from specific therapies.

SUMMARY

The recent introduction of CLAD importantly changed the clinical practice in lung transplant recipients. Given the relative low accuracy of the current diagnostic tools, future research should focus on specific biomarkers, more sensitive pulmonary function parameters and imaging techniques for timely CLAD diagnosis and phenotyping. Personalized or targeted therapeutic options for adequate prevention and treatment of CLAD are required.

Azithromycin and the treatment of lymphocytic airway inflammation after lung transplantation

Lymphocytic airway inflammation is a major risk factor for chronic lung allograft dysfunction, for which there is no established treatment. We investigated whether azithromycin could control lymphocytic airway inflammation and improve allograft function. Fifteen lung transplant recipients demonstrating acute allograft dysfunction due to isolated lymphocytic airway inflammation were prospectively treated with azithromycin for at least 6 months (NCT01109160). Spirometry (FVC, FEV1 , FEF25-75 , Tiffeneau index) and FeNO were assessed before and up to 12 months after initiation of azithromycin. Radiologic features, local inflammation assessed on airway biopsy (rejection score, IL-17(+)  cells/mm(2) lamina propria) and broncho-alveolar lavage fluid (total and differential cell counts, chemokine and cytokine levels); as well as systemic C-reactive protein levels were compared between baseline and after 3 months of treatment. Airflow improved and FeNO decreased to baseline levels after 1 month of azithromycin and were sustained thereafter. After 3 months of treatment, radiologic abnormalities, submucosal cellular inflammation, lavage protein levels of IL-1β, IL-8/CXCL-8, IP-10/CXCL-10, RANTES/CCL5, MIP1-α/CCL3, MIP-1β/CCL4, Eotaxin, PDGF-BB, total cell count, neutrophils and eosinophils, as well as plasma C-reactive protein levels all significantly decreased compared to baseline (p < 0.05). Administration of azithromycin was associated with suppression of posttransplant lymphocytic airway inflammation and clinical improvement in lung allograft function.

Adenosine 5'-monophosphate challenge elicits a more peripheral airway response than methacholine challenge

Adenosine 5'-monophosphate (AMP) and methacholine are commonly used to assess airway hyperreactivity. However, it is not fully known whether the site of airway constriction primarily involved during challenges with either agent is similar. Using a ventilation distribution test, we investigated whether the constriction induced by each agent involves the lung periphery in a similar fashion. Ventilation distribution was evaluated by the phase III slope (S) of the single-breath washout, using gases with different diffusivities like helium (He) and hexafluorosulfur (SF(6)). A greater postchallenge increase in S(He) reflects alterations at the level of terminal and respiratory bronchioles, while a greater increase in S(SF6) reflects alterations in alveolar ducts, increases to an equal extent reflecting alterations in more proximal airways where gas transport is still convective for both gases. S(SF6) and S(He) were measured in 15 asthma patients before and after airway challenges (20% forced expired volume in 1-s fall) with AMP and methacholine. S(He) increased to a greater extent than S(SF6) after AMP challenge (5.7 vs. 3.7%/l; P = 0.002), with both slopes increasing to an equal extent after methacholine challenge (3.1%/l; P = 0.959). The larger increase in S(He) following AMP challenge suggests distal ventilation impairment up to the level of terminal and respiratory bronchioles. With methacholine, the similar increases in S(He) and S(SF6) suggest a less distal impairment. AMP, therefore, seems to affect more extensively the very peripheral airways, whereas methacholine seems to have an effect on less distal airways.

A review of the potential applications and controversies of non-invasive testing for biomarkers of aspiration in the lung transplant population

Despite improvements in one-yr survival following lung transplantation, five-yr survival lags significantly behind the transplantation of other solid organs. The contrast in survival persists despite advancements in anti-rejection regimens, suggesting a non-alloimmune mechanism to chronic lung transplant failure. Notably, markers of aspiration have been demonstrated in bronchoalveolar lavage (BAL) fluid concurrent with bronchiolitis obliterans syndrome (BOS). This recent evidence has underscored gastroesophageal reflux (GER) and its associated aspiration risk as a non-alloimmune mechanism of chronic lung transplant failure. Given the suggested safety and efficacy of laparoscopic anti-reflux procedures in the lung transplant population, identifying those at risk for aspiration is of prime importance, especially concerning the potential for long-term improvements in morbidity and mortality. Conventional diagnostic methods for GER and aspiration, such as pH monitoring and detecting pepsin and bile salts in BAL fluid, have gaps in their effectiveness. Therefore, we review the applications and controversies of a non-invasive method of defining reflux injury in the lung transplant population: the detection of biomarkers of aspiration in the exhaled breath condensate. Only by means of assay standardization and directed collaboration may such a non-invasive method be a realization in lung transplantation.

Lung transplantation, gastroesophageal reflux, and fundoplication

Lung transplantation is an accepted treatment strategy for end-stage lung disease; however, bronchiolitis obliterans syndrome is a major cause of morbidity and mortality. This review explores the role of gastroesophageal reflux disease in bronchiolitis obliterans syndrome and the evidence suggesting the benefits of anti-reflux surgery in improving lung function and survival. There is a high prevalence of gastroesophageal reflux in patients post lung transplantation. This may be due to a high preoperative incidence, vagal damage and immunosuppression. Reflux in these patients is associated with a worse outcome, which may be due to micro-aspiration. Anti-reflux surgery is safe in selected lung transplant recipients; however there has been one report of a postoperative mortality. Evidence is conflicting but may suggest a benefit for patients undergoing anti-reflux surgery in terms of lung function and survival; there are no controlled studies. The precise indications, timing, and choice of fundoplication are yet to be defined, and further studies are required.

Prevalence of gastroesophageal reflux in end-stage lung disease candidates for lung transplant

BACKGROUND

Aspiration secondary to gastroesophageal reflux has been postulated to be a contributing factor in bronchiolitis obliterans after lung transplantation. It is not clear whether gastroesophageal reflux is a preexisting condition or secondary to intraoperative vagal injury or drug-induced prolonged gastric emptying.

METHODS

The prevalence of gastroesophageal reflux was examined in 78 consecutive end-stage lung disease patients assessed for lung transplantation: emphysema, 21; cystic fibrosis, 5; idiopathic pulmonary fibrosis, 26; scleroderma, 10; and miscellaneous diseases, 16. All underwent esophageal manometry. Two-channel esophageal 24-hour pH testing was completed in 76 patients. Gastric emptying studies were conducted in 36 patients.

RESULTS

Typical gastroesophageal reflux symptoms were documented in 63% of patients. The lower esophageal sphincter was hypotensive in 72% of patients, and 33% had esophageal body dysmotility. Prolonged gastric emptying was documented in 44%, and 38% had abnormal pH testing. The overall DeMeester score was above normal in 32% of patients, and 20% had abnormal proximal pH probe readings.

CONCLUSIONS

Gastroesophageal reflux is highly prevalent in end-stage lung disease patients who are candidates for lung transplantation. Further investigation is needed to study the prevalence of gastroesophageal reflux after lung transplantation and its contribution to chronic allograft dysfunction.

The effect of reflux and bile acid aspiration on the lung allograft and its surfactant and innate immunity molecules SP-A and SP-D

Gastro-esophageal reflux and related pulmonary bile acid aspiration were prospectively investigated as possible contributors to postlung transplant bronchiolitis obliterans syndrome (BOS). We also studied the impact of aspiration on pulmonary surfactant collectin proteins SP-A and SP-D and on surfactant phospholipids--all important components of innate immunity in the lung. Proximal and distal esophageal 24-h pH testing and broncho-alveolar lavage fluid (BALF) bile acid assays were performed prospectively at 3-month posttransplant in 50 patients. BALF was also assayed for SP-A, SP-D and phospholipids expressed as ratio to total lipids: phosphatidylcholine; dipalmitoylphosphatidylcholine; phosphatidylglycerol (PG); phosphatidylinositol; sphingomyelin (SM) and lysophosphatidylcholine. Actuarial freedom from BOS was assessed. Freedom from BOS was reduced in patients with abnormal (proximal and/or distal) esophageal pH findings or BALF bile acids (Log-rank Mantel-Cox p < 0.05). Abnormal pH findings were observed in 72% (8 of 11) of patients with bile acids detected within the BALF. BALF with high levels of bile acids also had significantly lower SP-A, SP-D, dipalmitoylphosphatidylcholine; PG and higher SM levels (Mann-Whitney, p < 0.05). Duodeno-gastro-esophageal reflux and consequent aspiration is a risk factor for the development of BOS postlung transplant. Bile acid aspiration is associated with impaired lung allograft innate immunity manifest by reduced surfactant collectins and altered phospholipids.

Pathologic correlates of bronchiolitis obliterans syndrome in pulmonary retransplant recipients

RATIONALE

The main hindrance to long-term success of lung transplantation is bronchiolitis obliterans syndrome (BOS), generally thought to be a manifestation of chronic allograft rejection. BOS is associated histologically with epithelial injury, bronchocentric mononuclear inflammation, and fibrosis of small airways known as bronchiolitis obliterans (BO). Few studies have directly compared clinical, radiographic, and histologic findings of BOS and BO, particularly in the era of improved immunosuppression and infection prophylaxis. Patients undergoing pulmonary retransplantation for BOS provide a unique opportunity to investigate these relationships.

METHODS

All patients who underwent pulmonary retransplantation for BOS from 1992 to 2004 at Duke University Medical Center were reviewed. Pathology findings in explanted lung allografts were compared with clinical, radiographic, and transbronchial biopsy data.

RESULTS

Over the 12-year study period, 12 patients underwent pulmonary retransplantation for BOS. The median time to BOS was 517 days (intraquartile range, 396 to 819.8 days). BOS scores prior to retransplantation were 2 in 2 patients and 3 in 10 patients. We developed a semiquantitative scoring system for epithelial, inflammatory, and fibrotic changes in affected airways to permit better comparison between BO and BOS. Somewhat surprisingly, only 50% (6 of 12 patients) had severe fibrotic changes, although all had some degree of epithelial injury, fibrosis, or inflammation centered around the bronchi and bronchioles. Furthermore, pathology findings other than BO were present in most explanted allografts and included cholesterol clefts (n = 4), focal invasive aspergillosis (n = 1), interstitial fibrosis (n = 2), and chronic vascular rejection (n = 1).

CONCLUSIONS

In this series of patients with advanced BOS undergoing retransplantation, at least some degree of BO was present in all explanted allografts. However, the degree of epithelial changes, fibrosis, and inflammation present among affected bronchi varied considerably. Furthermore, a wide range of pathologic processes of potential clinical significance were evident in half of the patients. We conclude that significant histologic heterogeneity exists among patients undergoing retransplantation for BOS, potentially contributing to the variability of patient responses to treatment.

Comparative clinicopathology of obliterative bronchiolitis and diffuse panbronchiolitis

BACKGROUND

The progressive airway obliteration caused by obliterative bronchiolitis (OB) has been widely noted in the world. In contrast, the obstructive respiratory disorder caused by diffuse panbronchiolitis (DPB) has been reported mainly from Japan. Therefore, there might be a considerable overlap between OB and DPB in Japan.

OBJECTIVES AND METHODS

To clarify the clinicopathological similarities as well as the differences between OB and DPB, 15 patients with OB and 6 patients with DPB were evaluated clinicopathologically.

RESULTS

The underlying disorders in OB were graft-versus-host disease (GVHD) in 7, rheumatoid arthritis in 3, Kartagener's syndrome in 2, and polymyositis/dermatomyositis, non-tuberculous mycobacterial disease and mycoplasmal pneumonia in one each. The lung pathology demonstrated that the primary obstructive lesions were in the membranous bronchioli in OB. In contrast, they were confined to the respiratory bronchioli in DPB. In addition, OB was classified into two major morphologic types, namely, constrictive and cellular. Clinical manifestations included cough and/or dyspnea in 13 with OB and in 6 with DPB, chronic parasinusitis in 3 with cellular OB and in 6 with DPB. The pulmonary function tests revealed obstructive impairments in all patients with OB and DPB. The chest CT images showed small centrilobular nodules in 64% of those with OB and in all with DPB. The prognosis of constrictive OB was worse than that of cellular OB and DPB.

CONCLUSIONS

This study demonstrated that histopathologically marked differences existed between OB and DPB, although striking similarities in clinical manifestations were also noted in both diseases.

Monitoring the lung periphery of transplanted lungs

Lung transplantation is now accepted as a viable therapeutic option for patients with end-stage lung diseases, but long-term survival is threatened by bronchiolitis obliterans (BO), which is regarded as a manifestation of chronic allograft rejection. We have used studies of ventilation distribution for the early detection of this complication. In a prospective study of 57 bilateral-lung transplant recipients, we showed that the slope of phase III of the helium single-breath washout, which targets inhomogeneities of ventilation distribution in the terminal and respiratory bronchioles, was particularly sensitive to the development of BO. In a preliminary study using nitrogen multiple-breath washouts, we showed that S(acin) and S(cond), which reflect structural changes in the acinar and conductive lung zones, were both markedly increased in patients with BO. Taken together, these studies demonstrate that monitoring the function of the allograft by measuring the distribution of ventilation in the lung periphery may be a clinically valuable tool.

Bile acid aspiration and the development of bronchiolitis obliterans after lung transplantation

BACKGROUND

Aspiration of gastroesophageal refluxate may contribute to lung transplant bronchiolitis obliterans syndrome (BOS). We investigated bile acids in bronchoalveolar lavage fluid (BALF) and studied its role in BOS.

MATERIALS AND METHODS

Surveillance pulmonary function tests and BALF were evaluated in 120 lung recipients. BOS-(0p-3) was diagnosed after 6 months' survival. BOS was defined as "early" if diagnosed within 12 months after a transplant. BALF was assayed for differential cell count, bile acids, and interleukins 8 and 15. Bile acids were considered elevated if greater than normal serum levels ( or =8 micromol/L).

RESULTS

Elevated BALF bile acids were measured in 20 (17%) of 120 patients. BOS was diagnosed in 36 (34%) of 107 patients and judged "early" in 21 (57%) of 36. Median BALF bile acid values were 1.6 micromol/L (range, 0-32 micromol/L) in BOS patients and 0.3 micromol/L (range, 0-16 micromol/L) in non-BOS patients ( P = .002); 2.6 micromol/L (range, 0-32 micromol/L) in early BOS patients and 0.8 micromol/L (range, 0-4.6 micromol/L) in late BOS patients, ( P = .02). Bile acids correlated with BALF IL-8 and alveolar neutrophilia (r = 0.3, P = .0004, and r = 0.3, P = .004, respectively), but not with IL-15. Freedom from BOS was significantly shortened in patients with elevated BALF bile acids (Cox-Mantel test, P = .0001).

CONCLUSIONS

Aspiration of duodenogastroesophageal refluxate is prevalent after lung transplantation and is associated with the development of BOS. Elevated BALF bile acids may promote early BOS development via an inflammatory process, possibly mediated by IL-8 and alveolar neutrophilia.

Lung Transplantation Biopsy Specimens With Bronchiolitis Obliterans or Bronchiolitis Obliterans Organizing Pneumonia Due to Aspiration

Context.—Bronchiolitis obliterans (BO) is generally thought to be a marker of chronic airway rejection in patients who have undergone lung transplantation. Bronchoscopic biopsy specimens, by virtue of their small size, may sample only BO and not a lesion of bronchiolitis obliterans organizing pneumonia (BOOP). A role for ongoing chronic infection or aspiration has also been suggested, and the distinction of these etiologies may be difficult clinically and pathologically.

Objective.—To investigate the etiology of BO and BOOP in lung transplantation patients who had chronic aspiration.

Design.—This is a clinicopathologic study of 7 patients who had undergone lung transplantation in which biopsy findings suggested the possibility of chronic airway rejection but in which aspiration was subsequently proven as a cause of the bronchiolar disease.

Results.—All patients were men, who ranged in age from 19 to 57 years. A clinical diagnosis of aspiration was considered based on history, acid reflux testing, and radiographic findings in all 7 patients. Three patients had BO and 4 patients had BOOP. Histiocytic giant cells or foreign material was absent. The interval from transplantation to BO ascribed to aspiration ranged from 2.5 months to 7 years. The patients were treated aggressively with medication for gastroesophageal reflux disease. Their respiratory function and chest radiography results improved.

Conclusion.—Although BO may be a manifestation of rejection, it may also be a manifestation of aspiration. Because the latter is potentially correctable, aspiration should be considered etiologically in lung transplantation patients with either BO or BOOP. Reliable distinction between aspiration-related or rejection-related BO and BOOP cannot be made on morphologic grounds alone. Clinical and radiologic correlations are indicated to establish the distinction.

[Bronchiolitis with airflow obstruction in adults]

PURPOSE

The purpose of this paper is twofold: to describe the clinical and anatomical characteristics of bronchiolitis associated with airflow obstruction in adults; to present through a clinical approach, a classification of the main aetiologies or pathological frames associated with that entity.

KEY POINTS

The constrictive bronchiolitis type is the most frequently encountered. On clinical grounds, cough, crackles, and a progressive dyspnea develop usually within a few weeks. Radiological signs of bronchiolar abnormalities are best visualized on high resolution expiratory CT scan. The decrease in maximal airflows and oxygen tension is of limited amplitude and poorly reversible with bronchodilators. Diagnosis is easily performed when a causative event, or the clinical context, can be delineated: inhalation of toxic fumes, diffuse bronchiectasis, rheumatoid arthritis, lung or bone marrow transplantation. Delayed formation of bronchiectasis in the central airways is common. The treatment is not standardized; corticosteroids are usually prescribed as a first line therapy; the benefit of the addition of, or substitution with immunosuppressive drugs has not been adequately evaluated, but is, on the mean, of limited amplitude.

PERSPECTIVES

Recent advances in the identification of inhaled agents toxic for the distal airways help in establishing appropriate measures of prevention. When the aetiology of the bronchiolitis cannot be suspected, extensive search of a causative agent should be performed, including microbial and mineral analysis of bronchoalveolar products. Negative results should lead to perform a surgical lung biopsy. The study of chronic rejection processes in animal models of lung transplantation, the identification of inhibitory factors of bronchiolar fibrogenesis, and the efficacy of some anti-cytokines on inflammatory processes could result in new therapeutic approaches.

Association between acute and chronic graft-versus-host disease and bronchiolitis obliterans organizing pneumonia in recipients of hematopoietic stem cell transplants

Bronchiolitis obliterans organizing pneumonia (BOOP) has been reported following hematopoietic stem cell (HSC) transplantation, but the clinical features and risk factors for this disorder have not been well characterized. This case-control study of 49 patients with histologic BOOP and 161 control subjects matched by age and year of transplantation describes the clinical features and analyzes the risk factors for BOOP following HSC transplantation. Data on clinical features and outcome were collected by chart review. Odds ratios, estimating the relative risk of BOOP in allogeneic HSC recipients, were calculated by conditional logistic regression with adjustment for potential confounding factors. Clinical features of BOOP in this population were similar to idiopathic BOOP and BOOP occurring in other disease settings. There was an association between acute and chronic graft-versus-host disease (GVHD) and the subsequent development of BOOP (odds ratios, 3.8 [95% CI, 1.2 to 12.3] and 3.1 [95% CI, 1.1 to 9.2], respectively). Patients with BOOP were more likely to have acute GVHD involving the skin (odds ratio, 4.6; P =.005) and chronic GVHD involving the gut (odds ratio, 6.6; P =.018) and oral cavity (odds ratio, 5.9; P =.026). This study shows that histologic BOOP following HSC transplantation has clinical features that resemble idiopathic BOOP and is strongly associated with prior acute and chronic GVHD. These results have important implications for the care of patients who develop respiratory symptoms after HSC transplantation and may help elucidate the pathogenesis of idiopathic BOOP.

Lung Transplantation Exacerbates Gastroesophageal Reflux Disease *

INTRODUCTION

A high prevalence of gastroesophageal reflux (GER) has been reported in lung transplant recipients and is possibly linked to the development of bronchiolitis obliterans syndrome. The etiology of posttransplant GER remains unknown but may occur due to the transplant operation or posttransplant medications, or represent preexisting GER disease. We evaluated these possibilities by studying the nature and severity of GER in a cohort of patients before and after lung transplantation.

METHODS

Total, upright, and supine acid contact times were recorded in lung transplant recipients who underwent 24-h pH studies before and after transplantation. Patients also underwent esophageal manometry and gastric-emptying studies. Medications for acid suppression and gastric motility were discontinued before testing. Paired comparison between pretransplant and posttransplant results was performed using a paired t test.

RESULTS

Twenty-three patients were included in the analysis. The mean age was 51.5 years, and native diseases included emphysema (n = 11), cystic fibrosis (n = 4), pulmonary fibrosis (n = 3), and others (n = 5). Posttransplant studies occurred a median of 100 days after transplantation. After lung transplantation, the total acid contact time increased a mean of 3.7% (p = 0.03) and the supine acid contact time increased a mean of 6.4% (p = 0.019). Thirty-five percent (8 of 23 patients) had abnormal acid contact times before transplant, and 65% (15 of 23 patients) had abnormal acid contact after transplant. Changes in acid contact times were not explained by changes in esophageal or gastric motility. Only 20% (3 of 15 patients) with abnormal posttransplant pH studies were symptomatic.

CONCLUSIONS

There is a significant increase in GER after lung transplantation, as measured objectively by 24-h pH studies, despite a lack of symptoms in most patients. Further research is needed to determine the physiologic mechanisms of posttransplant GER and its impact on long-term allograft function.

Gastroesophageal reflux disease in lung transplant recipients

BACKGROUND

Chronic allograft dysfunction after lung transplantation contributes to poor long-term survival. A link between gastric aspiration and post-transplant lung dysfunction has been suggested, but little is known about the significance of gastroesophageal reflux disease (GERD) after lung transplantation.

METHODS

A retrospective study was performed to determine the prevalence of GERD in lung transplant recipients. Patients who underwent lung transplantation at Duke University, survived at least 6 months and had post-transplant 24-h pH studies were included in the analysis. Antireflux medications were discontinued prior to the pH study. Demographic data, pH study date and results, FEV1 at the time of the pH study, confirmed acute rejection episodes, and current medications were collected. The FEV1 ratio was calculated at the time of pH study (current FEV1/best post-transplant FEV1).

RESULTS

Forty-three patients met entry criteria. Studies were performed at a median of 558 d post-transplant. Thirty of forty-three (69.8%) patients tested had abnormal total acid contact times (normal: <5%). The mean acid contact times for all patients were 10% total, 11.8% upright and 7.9% supine. A negative correlation was found between total or upright acid reflux and FEV1 ratio at the time of studies (-0.341 and -0.419; p = 0.025 and p = 0.005, respectively). The effect of acid reflux on FEV1 ratio remained significant after multivariable analysis.

CONCLUSIONS

There is a high prevalence of GERD among selected lung transplant recipients who had pH studies performed and its presence is associated with worse pulmonary function. Future studies are needed to assess whether GERD contributes to the pathogenesis of bronchiolitis obliterans syndrome (BOS).

Detection of obliterative bronchiolitis after lung transplantation by indexes of ventilation distribution

Obliterative bronchiolitis (OB) is the first cause of death of long-term survivors of lung transplantation. The diagnosis is based on pathology and/or on an irreversible decrease in forced expiratory volume in 1 s (FEV(1)) below 80% of the best postoperative value. We tested whether indexes of ventilation distribution may provide evidence of OB before conventional pulmonary function tests (PFTs). Fifty-seven patients with heart-lung (n = 47) or double-lung (n = 10) transplantation were monitored with conventional PFTs and measurements of the slope of the alveolar plateau for He (S(He)), SF(6) (S(SF6)), and N(2) (S(N2)) obtained during single-breath washouts. The date at which a functional variable showed an irreversible change outside the 97.5% confidence interval was compared with the date at which a greater than 20% fall in FEV(1) was observed. A total of 1,929 tests (median, 30 tests per patient) were performed during the 1,215 d (range, 164-2,829 d) of follow-up. Eighteen patients showed an irreversible and greater than 20% fall in FEV(1) during the course of the study. This alteration was preceded by a rise in S(He) in 17 patients and by a rise in S(N2) in 16 patients, which indicated a more heterogeneous ventilation. The median time interval between the change in S(He) and S(N2) and the 20% decrease in FEV(1) was 356 and 168 d, respectively, with seven patients showing an interval of 18 mo or more. Conventional PFTs, including midexpiratory flow rates, deteriorated after indexes of ventilation distribution. Thirty-nine patients did not show any significant and irreversible alteration in conventional PFTs over the study period; only seven of these patients developed significant alterations in ventilation distribution. We conclude that measurements of ventilation distribution detect posttransplant OB much earlier than conventional PFTs.

Short air bubble in the gastric fundus during fasting: radiographic sign of gastroparesis after lung transplantation

This study was undertaken to assess whether gastroparesis, as a chronic complication of lung transplantation, correlates with height of the gastric air bubble on chest radiographs of erect fasting subjects. Height of the gastric air bubble and presence or absence of a gastric air-fluid level were assessed on chest radiographic examinations (posteroanterior, lateral, upright position, during fasting, immediately after bronchoscopy, median 148 days after transplantation) obtained on 3 separate days for each of 19 recipients of lung transplantation. Seven of the subjects (five women, two men) had chronic upper gastrointestinal symptoms after transplantation and a confirmed diagnosis of gastroparesis. The gastroparesis was idiopathic in six of the subjects and associated with cytomegalovirus gastritis in one subject. The other 12 subjects, each without upper gastrointestinal symptoms, served as controls. Median height of the gastric air bubble was significantly less in the gastroparetic (2.8 cm; range, 1.0-4.6 cm) than in the control (4.7 cm; range, 1.0-12.4 cm) group (p<0.05). Height of the gastric air bubble was at most 4.6 cm among the seven gastroparetic subjects, whereas it exceeded 5.0 cm on at least one occasion in 8 (67%) of the 12 control subjects (p<0.005). The likelihood of a gastric air-fluid level was 86% for symptomatic subjects and 25% for the control group (p<0.01). When lung transplantation is complicated by chronic gastroparesis, postbronchoscopic chest radiographic examinations of fasting subjects are associated with a gastric air bubble limited to high in the fundus, usually including a fluid level.

Lymphocytic airway infiltration as a precursor to fibrous obliteration in a rat model of bronchiolitis obliterans

BACKGROUND

Bronchiolitis obliterans is the most significant complication adversely affecting prolonged survival of lung allograft recipients. The evolution from the initial insult to the final pathologic entity is largely unknown. The aim of this study was to characterize the evolution of transplant-induced fibrous airway obliteration in a rat tracheal transplant model of bronchiolitis obliterans.

METHODS

Tracheal segments were transplanted from Brown Norway rats to Brown Norway rats (isografts) or to Lewis rats (allografts). Grafts were implanted into a subcutaneous pouch and an abdominal omental wrap. They were harvested at 14 different time points (from 1 day to 1 year after transplantation) and assessed histologically.

RESULTS

The fibrous airway obliteration developed only in allografts showing a triphasic time course: an initial ischemic phase (observed in both isografts and allografts) was followed by a marked lymphocytic infiltrative phase with complete epithelial loss (observed only in allografts, P<0.01), and finally by an obliterative phase with fibrous obliteration of the allograft airway lumen (P<0.01).

CONCLUSIONS

This animal model shows a distinct and reproducible triphasic time course in the development of obliterative airway lesions in allografts. It confirms that the mechanism leading to airway obliteration is immune mediated as only allografts showed this lesion and that lymphocytic infiltration is a precursor of the lesion in this model. The insights into the different phases demonstrated may lead to novel approaches regarding the type and timing of therapeutic interventions.

Obliterative bronchiolitis

Obliterative bronchiolitis following lung transplantation is common and potentially devastating. Its exact cause is undefined, but multiple immune and nonimmune processes contribute to its pathogenesis. Severe acute rejection and recurrent acute rejection have been shown to confer the greatest risk for obliterative bronchiolitis, signifying the central importance of alloimmunity in the disease process. Treatment of established disease with intensification of immune suppression has been of limited benefit, so current clinical strategies include early detection and minimization of risk. As our understanding of the disease evolves, it is hoped that effective interventions targeted at specific pathogenetic steps will emerge. In the meantime, obliterative bronchiolitis remains the most important and sinister long-term complication of lung transplantation.

Pathology of lung allografts in children and young adults

Heart-lung and lung transplantation have become acceptable therapeutic modalities for end-stage lung and heart conditions in children and young adults, but the posttransplantation pulmonary pathology in this age-group is poorly characterized. We present our experience with the pathology of lung transplantation in a cohort of 11 patients with a median age of 12.5 years, and median posttransplantation follow-up of 8.3 months. The findings are based on histological examination of 98 specimens, including five autopsy specimens from patients 20 years of age or younger. Our experience, combined with the data in other pediatric series, suggest that there is not a significant difference in the prevalence or severity of acute rejection or bronchiolitis obliterans (BO) between adult and pediatric lung transplant recipients. Lymphocytic bronchitis/bronchiolitis showed a more prominent association with BO in our series than previously reported in adult studies. Chronic vascular rejection in the pediatric lung transplant recipients can occur earlier than reported in adults and is associated with a grave prognosis. Overwhelming infection was a major cause of death in our experience. In particular, our data combined with the previous reports indicate that adenoviral pneumonia is a relatively common pathogen in the pediatric population and is a major cause of mortality in this age-group.

Histopathological study of Sauropus androgynus-associated constrictive bronchiolitis obliterans: a new cause of constrictive bronchiolitis obliterans

The development of constrictive bronchiolitis obliterans in patients who have ingested Sauropus androgynus juice has not been previously reported. We describe four patients with S. androgynus-associated constrictive bronchiolitis obliterans who underwent open lung biopsies for histopathological analysis. This article aims to recognize the possible pathogenesis of the disease. The spectrum of histologic changes ranged from slight bronchiolar inflammation and fibrosis to marked submucosal fibrosis causing complete cicatricial obliteration of the lumen. A dense eosinophil infiltrate was noted in the bronchiolar submucosa or fibrotic tissue of the completely obliterated bronchioles in two patients. Immunohistochemical studies revealed that lymphocytic infiltrate consisted mainly of T lymphocytes in all patients. Immunofluorescent stains for immunoglobulin (Ig)G, IgA, IgM, C1q, C3, and C4 were negative. Electron microscopy disclosed no immune complex deposition in the specimens examined. Although the role of antibody- and complement-mediated reaction is not supported by the negative results of immunofluorescent and electron microscopic studies, the common finding of the predominant T-lymphocytic infiltrate suggests that a T-cell mediated immune response is involved in the pathogenesis of the disease. Furthermore, the finding of a heavy lymphocytic infiltrate in many bronchioles without significant collagen deposition suggests that the lymphocytic infiltrate may precede the tissue fibrosis. In addition, the presence of a dense eosinophil infiltrate may combine with lymphocytes and other immunologic and mesenchymal cells to promote antigen-specific stimulation of lymphocytes and induction of fibrosis.

Bronchiolitis obliterans organizing pneumonia (BOOP) in lung transplant recipients

We reviewed all tissue specimens from 163 transplant patients (108 double lung transplant [DLT], 55 single lung transplant [SLT]) between November 1983 and January 1994 for abnormalities indicating bronchiolitis obliterans organizing pneumonia (BOOP) and found 17 cases (14 DLT and 3 SLT). Of the three SLTs, BOOP was diagnosed by open lung biopsy (OLB) in two and one was found at autopsy. Of the 14 DLTs, BOOP was diagnosed by transbronchial biopsy (TBB) specimens (9), OLB specimens (2), autopsy (1), TBB and OLB specimens (1), and OLB specimens and autopsy (1). BOOP was found between 1 and 43 months posttransplantation; time of survival from diagnosis was between 2 and 36 months with 9 patients presently alive. Concurrent pathologic diagnosis at the time of BOOP findings were as follows: acute rejection (7) (grade 1 [4] and grade 2 [3]), BO and grade 1 rejection (2), BO and grade 2 rejection (2), BO and Aspergillus infection (1), acute alveolar injury (1), acute alveolar injury and pulmonary embolus (1), acute rejection (grade 1) and Burkholderia cepacia pneumonia (1). No other pathologic diagnosis was found in 1 patient. In total, 11 of 17 patients (65%) had associated acute rejection. Of the 17 patients, 7 subsequently developed BO and 3 had BO before the finding of BOOP. Death occurred in 8 patients (5 DLT and the 3 SLT) between 2 and 6 months after the diagnosis. We conclude that BOOP is an important complication after lung transplantation; it was present in 13% of DLTs and 5% of SLTs. BOOP was most often associated with acute rejection.

Importance of diffuse aspiration bronchiolitis caused by chronic occult aspiration in the elderly

Diffuse aspiration bronchiolitis (DAB) is a new term that we proposed to define a clinical entity that is characterized by a chronic inflammation of bronchioles caused by recurrent aspiration of foreign particles. In the present study, a total of 4,880 consecutive autopsies were reviewed and we found 31 patients with DAB (0.64%). To investigate the clinicopathologic features of DAB, the 23 patients with DAB (age, 81.2 +/- 6.2 years [mean +/- SD]), from whom clinical information was available, had their features compared to those of 40 randomly selected patients with aspiration pneumonia (age, 81.9 +/- 8.3 years [mean +/- SD]). Oropharyngeal dysphagia was observed in half of the patients with DAB, and two thirds of patients with DAB were bedridden. The onset of DAB was more insidious than aspiration pneumonia, and in half of the patients with DAB episodes of aspiration were unrecognized. Neurologic disorders (52.2%) and dementia (47.8%) were common associated diseases. Most patients with DAB showed signs of bronchorrhea, bronchospasm, and dyspnea. The macroscopic appearance of the cut surface of DAB lung showed diffusely scattered miliary yellowish nodules that resembled those of diffuse panbronchiolitis (DPB). Histologic findings of DAB were characterized by localization of chronic mural inflammation with foreign body reaction in bronchioles. Recurrence of small amounts of aspiration might play a role in the pathogenesis of DAB. In view of possible therapeutic intervention, we emphasized the importance of recognizing this entity and differentiating DAB from pulmonary diseases associated with bronchospasm in the elderly, in particular, late-onset asthma and DPB.

Bronchiolitis obliterans organizing pneumonia-like reactions: a nonspecific response or an atypical form of rejection or infection in lung allograft recipients?

Bronchiolitis obliterans organizing pneumonia (BOOP) is a ubiquitous entity, known to occur either idiopathically or in association with various pulmonary disorders. Histologically, it is characterized by myxomatous connective tissue plugs present in the lumen of bronchioles with extension into the alveoli. Its significance in lung allograft recipients is not well documented. The authors reviewed all post-lung transplant biopsies (565 transbronchial; 19 open), explanted lungs for retransplantation (six), and autopsies (38) from 115 patients. A total of 32 patients (18 females and 14 males) showed histological evidence of BOOP-like reactions (ie, Masson bodies in 44 transbronchial and seven open lung biopsies). The mean age was 47 years (range = 14 to 69 years). Sixteen patients were recipients of single lungs, 14 received bilateral single lungs, and two had heart and double-lung transplants. BOOP-like reactions (BOOP-LRs) occurred as early as day 5 and as late as day 1,208 (40 months) posttransplantation. Twenty patients had one biopsy showing BOOP-LR, of which three patients had resolving mild acute rejection, four had ongoing minimal acute rejection, seven had ongoing mild acute rejection, one each had ongoing moderate and bronchiolar rejection, and four showed associated cytomegalovirus (CMV) pneumonitis. Seven patients had two biopsies each of BOOP-LR of which six were associated with ongoing minimal or mild acute rejection, and one had resolving mild acute rejection. Three patients had three biopsies each of BOOP-LR all associated with ongoing minimal or mild acute rejection. Two patients had four biopsies each, showing BOOP-LR, with ongoing mild or moderate acute rejection or CMV pneumonitis. Forty of the total 115 lung transplant patients (34.8%) have developed bronchiolitis obliterans syndrome (BOS) or chronic airway rejection. Twelve of these patients are from the study group, of which five have a biopsy proven histological diagnosis of obliterative bronchiolitis (OB), and the remaining seven patients have been diagnosed clinically by deteriorating lung function tests. The authors conclude that BOOP-LR in the lung transplant setting result from acute epithelial injury secondary to either allograft rejection or an ongoing infection and are not a component of, nor do they necessarily predispose to, chronic rejection.

Gastroparesis after lung transplantation. Potential role in postoperative respiratory complications

BACKGROUND

We observed an unexpectedly high incidence of postoperative gastroparesis among lung and heart-lung transplant recipients.

PURPOSE

To identify the incidence of GI complications and to describe the clinical profiles of patients who developed symptomatic gastroparesis after lung transplantation.

PATIENTS AND METHODS

Retrospective study of GI symptoms and complications identified during 3 years of follow-up of 38 adult lung and heart-lung transplant recipients.

RESULTS

Sixteen of 38 patients (42%) reported one or more GI complaint and received a specific GI diagnosis. Nine of 38 patients (24%) complained of early satiety, epigastric fullness, anorexia, nausea, or vomiting. Gastroparesis was suspected when endoscopic evaluation revealed undigested food in the stomach after overnight fast and symptoms could not be attributed to peptide disease or cytomegalovirus gastritis. Delayed gastric emptying was confirmed by gastric scintigraphy. Mean gastric empty (t1/2) was 263 +/- 115 min (normal < 95 min). Gastroparesis occurred in 4 of 13 right lung, 2 of 12 left lung, 1 of 9 bilateral single lung, and 2 of 4 heart-lung recipients (p = NS). Patients responded partially to metoclopramide or cisapride, with the exception of two patients who required placement of jejunal feeding tubes secondary to severe symptoms. In long-term follow-up, symptoms resolved in all patients and treatment with medications or mechanical intervention was successfully discontinued. Four of nine patients (44%) suffering from gastroparesis developed obliterative bronchiolitis (OB). Food particles were discovered in the BAL fluid of two such symptomatic patients. In contrast, only 6 of 29 (21%) nonsymptomatic patients developed OB (p = 0.16).

CONCLUSION

Symptomatic gastroparesis is a frequent complication of lung or heart-lung transplantation that may promote microaspiration into the lung allograft.

Isolated lung transplantation in children: pathological diagnosis and incidence of pulmonary complications

The pathological findings in the allografts of 14 children who underwent lung transplantation (LT) at St. Louis Children's Hospital, St. Louis, MO, in the period between July 1990 and May 1992 were reviewed. The study is based on histological analysis of 63 transbronchial biopsy (TBB) specimens, eight open lung biopsy specimens, and three pneumonectomy specimens. The mean age at transplantation was 10.5 years (range, 1 to 17 years) and the average follow-up period was 5.7 months. Sufficient tissue for an adequate pathological examination was obtained in 58 (92%) TBB specimens. Each specimen consisted of a mean of 6.12 tissue fragments, but only 4.79 fragments contained actual lung parenchyma for suitable examination. Ten patients (71%) had 23 biopsy-proven episodes of acute rejection with a frequency of 1.64 episodes per patient. The first episode was documented at a mean of 19 days after transplantation. Six patients (42.8%) developed bronchiolitis obliterans (BO). The definitive diagnosis of this condition was made either by open lung biopsy (n = 3) or on allograft pneumonectomy (n = 1), and it was infrequently recognized by TBB. Four of the six patients died less than 9 months after the diagnosis of BO was made, indicating the grave consequences of this complication. Two other deaths were attributed to the development of posttransplantation lymphoproliferative disorders.

Elevated levels of serum mucin-associated antigen in adult patients with cystic fibrosis

Previous studies using the CA 19-9 antibody have demonstrated that serum mucin levels in patients with cystic fibrosis (CF) are elevated and that the degree of elevation relates to the age of the patient and possibly to his or her clinical status. However, CA 19-9 only recognizes the mucin-associated blood group sialyl Le(a+) antigen, so mucin levels cannot be measured in patients without Lewis antigens. The present study used the 17B1 monoclonal antibody to measure serum mucin levels in normal subjects, and in patients with CF, patients with chronic obstructive pulmonary disease (COPD), and patients with lung transplants. Serum mucin levels were 25 ng/ml (+/- 1 SEM, n = 8) in normal subjects, 13,853 ng/ml (+/- 1,281, n = 25) in patients with CF, and 25.5 ng/ml (+/- 1.9, n = 17) in patients with COPD. Patients with CF who were sialyl Le(a-b-) also had elevated serum mucin levels (715 +/- 152, n = 2). Serum mucin levels of six lung transplant recipients with CF were elevated compared with those in normal subjects (4,621 +/- 765 ng/ml), but they were not different from serum mucin levels in six lung transplant recipients without CF (5,307 +/- 1.677 ng/ml). Preliminary characterization of the serum mucin antigen showed that: (1) in CF sera, the antigen is polydisperse and smaller than the antigen in normal sera; (2) the mucin antigen is distinct from ABO blood group antigens. Serum mucin levels may be a useful marker to follow a specific patient's response to therapy.

Bronchiolitis obliterans-organizing pneumonia (BOOP) in children with malignant disease

Four patients who had completed chemotherapy for malignant disease are presented. Unexpected findings of pulmonary infiltrates on chest radiographs of two patients and solitary and/or confluent nodules on CT in all four led to open lung biopsy. Histologic diagnosis in each case was bronchiolitis obliterans-organizing pneumonia (BOOP). This usually innocuous disorder can be differentiated histologically from the more severe pure bronchiolitis obliterans and should be considered in the differential diagnosis of pulmonary lesions associated with malignant disease.