Screening Strategies for Pulmonary Hypertension in Patients With Interstitial Lung Disease: A Multidisciplinary Delphi Study.

BACKGROUND: Pulmonary hypertension (PH) is a common complication of interstitial lung disease (ILD) and is associated with worse outcomes and increased mortality. Evaluation of PH is recommended in lung transplant candidates, but there are currently no standardized screening approaches. Trials have identified therapies that are effective in this setting, providing another rationale to routinely screen patients with ILD for PH. RESEARCH QUESTION: What screening strategies for identifying PH in patients with ILD are supported by expert consensus? STUDY DESIGN AND METHODS: The study convened a panel of 16 pulmonologists with expertise in PH and ILD, and used a modified Delphi consensus process with three surveys to identify PH screening strategies. Survey 1 consisted primarily of open-ended questions. Surveys 2 and 3 were developed from responses to survey 1 and contained statements about PH screening that panelists rated from -5 (strongly disagree) to 5 (strongly agree). RESULTS: Panelists reached consensus on several triggers for suspicion of PH including the following: symptoms, clinical signs, findings on chest CT scan or other imaging, abnormalities in pulse oximetry, elevations in brain natriuretic peptide (BNP) or N-terminal pro-brain natriuretic peptide (NT-proBNP), and unexplained worsening in pulmonary function tests or 6-min walk distance. Echocardiography and BNP/NT-proBNP were identified as screening tools for PH. Right heart catheterization was deemed essential for confirming PH. INTERPRETATION: Many patients with ILD may benefit from early evaluation of PH now that an approved therapy is available. Protocols to evaluate patients with ILD often overlap with evaluations for pulmonary hypertension-interstitial lung disease and can be used to assess the risk of PH. Because standardized approaches are lacking, this consensus statement is intended to aid physicians in the identification of patients with ILD and possible PH, and provide guidance for timely right heart catheterization.

A controlled trial of sildenafil in advanced idiopathic pulmonary fibrosis.

BACKGROUND: Sildenafil, a phosphodiesterase-5 inhibitor, may preferentially improve blood flow to well-ventilated regions of the lung in patients with advanced idiopathic pulmonary fibrosis, which could result in improvements in gas exchange. We tested the hypothesis that treatment with sildenafil would improve walk distance, dyspnea, and quality of life in patients with advanced idiopathic pulmonary fibrosis, defined as a carbon monoxide diffusion capacity of less than 35% of the predicted value. METHODS: We conducted a double-blind, randomized, placebo-controlled trial of sildenafil in two periods. The first period consisted of 12 weeks of a double-blind comparison between sildenafil and a placebo control. The primary outcome was the proportion of patients with an increase in the 6-minute walk distance of 20% or more. Key secondary outcomes included changes in oxygenation, degree of dyspnea, and quality of life. The second period was a 12-week open-label evaluation involving all patients receiving sildenafil. RESULTS: A total of 180 patients were enrolled in the study. The difference in the primary outcome was not significant, with 9 of 89 patients (10%) in the sildenafil group and 6 of 91 (7%) in the placebo group having an improvement of 20% or more in the 6-minute walk distance (P=0.39). There were small but significant differences in arterial oxygenation, carbon monoxide diffusion capacity, degree of dyspnea, and quality of life favoring the sildenafil group. Serious adverse events were similar in the two study groups. CONCLUSIONS: This study did not show a benefit for sildenafil for the primary outcome. The presence of some positive secondary outcomes creates clinical equipoise for further research. (Funded by the National Heart, Lung, and Blood Institute and others; ClinicalTrials.gov number, NCT00517933.)

Treprostinil to reverse pulmonary hypertension associated with idiopathic pulmonary fibrosis as a bridge to single-lung transplantation.

The available therapies and prognosis of idiopathic pulmonary fibrosis remain relatively poor, and concurrent pulmonary hypertension further increases the risk of death and complications after lung transplantation. Limited data exist for the treatment of pulmonary hypertension associated with idiopathic pulmonary fibrosis. We describe a case where intravenous treprostinil was used to bridge an elderly patient with idiopathic pulmonary fibrosis with severe pulmonary hypertension to successful single-lung transplantation.

Diagnosis and hemodynamic assessment of pulmonary arterial hypertension.

Pulmonary hypertension (PH) can occur as either a primary or a secondary process, and in general, its presence increases overall morbidity and mortality. Importantly, the majority of prior studies have been in the setting of idiopathic pulmonary arterial hypertension (IPAH); thus the following discussion focuses on IPAH. Because the majority of available diagnostic strategies lack sensitivity and specificity, the physician must maintain a high index of suspicion in considering PAH. This article provides an overview of the available diagnostic studies for PAH with a particular focus on hemodynamic assessment. Novel approaches to the often delayed diagnosis of PAH are being studied and are also discussed here.

Serum albumin concentration and waiting list mortality in idiopathic interstitial pneumonia.

BACKGROUND: Hypoalbuminemia is a reliable predictor of mortality in patients with various illnesses as well as a predictor of disability and mortality in healthy older adults. The association between hypoalbuminemia and mortality in patients with idiopathic interstitial pneumonia remains unknown. The objective of this study was to examine the relationship between serum albumin concentration and mortality in a large cohort of patients with idiopathic interstitial pneumonia listed for lung transplantation. METHODS: In patients classified as having idiopathic pulmonary fibrosis who were listed for lung transplantation with the United Network for Organ Sharing between January 1, 2004, and December 31, 2006 (n = 1,269), we studied the relationship between serum albumin concentration at the time of listing and mortality while awaiting transplantation. RESULTS: Lower serum albumin was associated with increased mortality rate. Patients with lower categories of serum albumin had increased mortality rates before and after multivariable adjustment (p value for linear trend < 0.0001). Analysis with serum albumin as a continuous predictor indicated that the mortality rate increased by 54% with each 0.5 g/dL decrease in serum albumin concentration (95% confidence interval, 32 to 79%). CONCLUSIONS: Lower serum albumin is strongly and independently associated with higher mortality in patients with idiopathic interstitial pneumonia on transplant waiting lists.

Right ventricular systolic pressure by echocardiography as a predictor of pulmonary hypertension in idiopathic pulmonary fibrosis.

RATIONALE: Pulmonary hypertension (PH) commonly complicates the course of patients with idiopathic pulmonary fibrosis (IPF). It has a significant impact on outcomes and is, therefore, important to detect. OBJECTIVES: We sought to characterize the accuracy and performance characteristics of the right ventricular systolic pressure (RVSP) as estimated by echocardiography (ECHO) alone and in conjunction with physiologic indices in predicting the presence of PH in IPF patients. METHODS: Cross-sectional study of IPF patients from two large tertiary centers in whom both ECHO and right-heart catheterization (RHC) were available. MEASUREMENTS AND MAIN RESULTS: There were 110 patients with available ECHOs and RHCs. Estimates of RVSP were reported in 60 of these patients (54.5%) of whom 22 (36.6%) had PH, while 16 of the 50 patients without RVSP estimate (32%) had PH. Twenty-four of 60 (40%) ECHOs accurately reflected the pulmonary arterial systolic pressure as measured by RHC. An optimal RVSP threshold for the screening of PH could not be detected. When assessed in combination with various thresholds of PFT and 6-minute walk test (6MWT) parameters, the performance characteristics of the RVSP were slightly improved. CONCLUSION: The RVSP is not an accurate test for the assessment of PH in IPF patients. Awareness of the various combinations of threshold values for RVSP with and without PFT and 6MWT might nonetheless assist clinicians in risk stratifying IPF patients for the presence of PH.

Validation of a method to screen for pulmonary hypertension in advanced idiopathic pulmonary fibrosis.

BACKGROUND: We have developed a method to screen for pulmonary hypertension (PH) in idiopathic pulmonary fibrosis (IPF) patients, based on a formula to predict mean pulmonary artery pressure (MPAP) from standard lung function measurements. The objective of this study was to validate this method in a separate group of IPF patients. METHODS: Cross-sectional study of 60 IPF patients from two institutions. The accuracy of the MPAP estimation was assessed by examining the correlation between the predicted and measured MPAPs and the magnitude of the estimation error. The discriminatory ability of the method for PH was assessed using the area under the receiver operating characteristic curve (AUC). RESULTS: There was strong correlation in the expected direction between the predicted and measured MPAPs (r = 0.72; p < 0.0001). The estimated MPAP was within 5 mm Hg of the measured MPAP 72% of the time. The AUC for predicting PH was 0.85, and did not differ by institution. A formula-predicted MPAP > 21 mm Hg was associated with a sensitivity, specificity, positive predictive value, and negative predictive value of 95%, 58%, 51%, and 96%, respectively, for PH defined as MPAP from right-heart catheterization > 25 mm Hg. CONCLUSIONS: A prediction formula for MPAP using standard lung function measurements can be used to screen for PH in IPF patients.

Prediction of pulmonary hypertension in idiopathic pulmonary fibrosis.

BACKGROUND: Reliable, noninvasive approaches to the diagnosis of pulmonary hypertension in idiopathic pulmonary fibrosis are needed. We tested the hypothesis that the forced vital capacity to diffusing capacity ratio and room air resting pulse oximetry may be combined to predict mean pulmonary artery pressure (MPAP) in idiopathic pulmonary fibrosis. METHODS: Sixty-one idiopathic pulmonary fibrosis patients with available right-heart catheterization were studied. We regressed measured MPAP as a continuous variable on pulse oximetry (SpO(2)) and percent predicted forced vital capacity (FVC) to percent-predicted diffusing capacity ratio (% FVC/% DL(co)) in a multivariable linear regression model. RESULTS: Linear regression generated the following equation: MPAP=-11.9+0.272 x SpO(2)+0.0659 x (100-SpO(2))(2)+3.06 x (% FVC/% DL(co)); adjusted R(2)=0.55, p<0.0001. The sensitivity, specificity, positive predictive and negative predictive value of model-predicted pulmonary hypertension were 71% (95% confidence interval (CI): 50-89%), 81% (95% CI: 68-92%), 71% (95% CI: 51-87%) and 81% (95% CI: 68-94%). CONCLUSIONS: A pulmonary hypertension predictor based on room air resting pulse oximetry and FVC to diffusing capacity ratio has a relatively high negative predictive value. However, this model will require external validation before it can be used in clinical practice.

High-resolution chest CT findings do not predict the presence of pulmonary hypertension in advanced idiopathic pulmonary fibrosis.

BACKGROUND: Reliable, noninvasive approaches to the diagnosis of pulmonary hypertension (PH) in patients with idiopathic pulmonary fibrosis (IPF) are needed. We tested the hypothesis that chest CT-determined extent of pulmonary fibrosis and/or main pulmonary artery diameter (MPAD) can be used to identify the presence of PH in patients with advanced IPF. METHODS: Cross-sectional study of 65 patients with advanced IPF and available right-heart catheterization and high-resolution chest CT. An expert radiologist scored ground-glass opacity, lung fibrosis, and honeycombing in the CT images on a scale of 0 to 4. These scores were also summed into a total profusion score. The main pulmonary artery was measured at its widest dimension on the supine full-chest sequence. At this same level, the widest aorta diameter was measured. RESULTS: Chest CT-determined fibrosis score, ground-glass opacity score, honeycombing score, total profusion score, diameter of the main pulmonary artery, and the ratio of the pulmonary artery to aorta diameter did not differ between those with and without PH. There was no significant correlation between mean pulmonary artery pressure and any of the chest CT-determined measures. CONCLUSIONS: High-resolution chest CT-determined extent of pulmonary fibrosis and/or MPAD cannot be used to screen for PH in advanced IPF patients.

Acute exacerbations of idiopathic pulmonary fibrosis.

The natural history of idiopathic pulmonary fibrosis (IPF) has been characterized as a steady, predictable decline in lung function over time. Recent evidence suggests that some patients may experience a more precipitous course, with periods of relative stability followed by acute deteriorations in respiratory status. Many of these acute deteriorations are of unknown etiology and have been termed acute exacerbations of IPF. This perspective is the result of an international effort to summarize the current state of knowledge regarding acute exacerbations of IPF. Acute exacerbations of IPF are defined as acute, clinically significant deteriorations of unidentifiable cause in patients with underlying IPF. Proposed diagnostic criteria include subjective worsening over 30 days or less, new bilateral radiographic opacities, and the absence of infection or another identifiable etiology. The potential pathobiological roles of infection, disordered cell biology, coagulation, and genetics are discussed, and future research directions are proposed.

Sildenafil improves walk distance in idiopathic pulmonary fibrosis.

Pulmonary hypertension is a common finding in patients with idiopathic pulmonary fibrosis (IPF), and is associated with increased morbidity and mortality. Therapy with sildenafil has been shown to decrease pulmonary vascular resistance in patients with pulmonary fibrosis and may improve functional status. Patients with IPF and documented pulmonary hypertension were followed up in an open-label study of sildenafil. The 6-min walk test distance (6MWD) was obtained before and after 3 months of sildenafil therapy. Fourteen patients were followed up in the study; 11 patients completed both 6-min walk tests. The mean improvement in walk distance was 49.0 m (90% confidence interval, 17.5 to 84.0 m). When all 14 patients were dichotomized into groups of "responders" (ie, >/= 20% improvement in 6MWD) or "nonresponders" (ie, < 20% change or unable to complete), 57% were classified as responders. Sildenafil is a promising and well-tolerated therapeutic agent for use in patients with IPF and pulmonary hypertension, and should be studied in a large, well-controlled trial.

Retrospective study of pulmonary function tests in patients presenting with isolated reduction in single-breath diffusion capacity: implications for the diagnosis of combined obstructive and restrictive lung disease.

OBJECTIVE: To examine the frequency and spectrum of diseases associated with isolated reduction in the diffusing capacity of lung for carbon monoxide (D(Lco)). PATIENTS AND METHODS: We retrospectively identified all potentially dyspneic patients who had pulmonary function tests (PFTs) performed at the Mayo Clinic in Jacksonville, Fla, between January 1, 1990, and June 30, 2000, that showed reduced D(Lco) (< 70% of predicted), normal lung volumes (total lung capacity and residual volume > 80% and < 120% of predicted, respectively), and airflow variables (forced expiratory volume in 1 second and forced vital capacity values > 80% of predicted and forced expiratory volume in 1 second/forced vital capacity ratio > 70% of predicted). Only patients who had also undergone chest computed tomography (CT) and echocardiography within 1 month of PFTs were studied. RESULTS: Of the 38,095 patients who underwent PFTs during the study period, 179 (0.47%; 95% confidence interval [CI], 0.40%-0.54%) had isolated D(Lco) abnormalities. The 27 patients (15.1%; 95% CI, 10.2%-21.2%) who had also undergone chest CT and echocardiography within 1 month of PFTs form the study cohort reported herein. Their mean D(Lco) was 50% +/- 15% (95% CI, 45%-56%) with average normal pulse oxygen saturation at rest and mild hypoxemia with activity. Thirteen of the 27 patients (48%; 95% CI, 28.7%-68.1%) had underlying emphysema evident on CT. Eleven of these 13 patients had emphysema associated with a restrictive lung process. The 14 patients without emphysema had interstitial lung disease, pulmonary vascular disease, and other isolated findings. Six patients with combined emphysema and idiopathic pulmonary fibrosis accounted for the largest percentage (22%) of patients with Isolated D(Lco) reduction. The mean +/- SD smoking history of the 27 patients in the study cohort was 36 +/- 33 pack-years (range, 0-116 pack-years). CONCLUSION: Dyspneic patients with respiratory symptoms and normal lung volumes and airflows associated with Isolated reduction in D(Lco) should be evaluated for underlying diseases such as emphysema, with or without a concomitant restrictive process, and pulmonary vascular disease.

Circulating peripheral blood fibrocytes in human fibrotic interstitial lung disease.

Fibrotic interstitial lung diseases are illnesses of unknown cause characterized by progressive decline in lung function. Fibrocytes are bone marrow-derived, circulating progenitor cells capable of differentiating into diverse mesenchymal cell types. Prior work has shown fibrocytes to traffic to the lung via the CXCL12-CXCR4 chemokine axis in an animal model of pulmonary fibrosis. We therefore assessed the relevance of fibrocytes in patients with fibrotic interstitial lung disease. We found enhanced expression of CXCL12 in both the lungs and plasma of patients with lung fibrosis. CXCL12 levels were associated with an order of magnitude higher number of circulating fibrocytes in the peripheral blood of these patients. Most of the circulating fibrocytes in patients with interstitial lung diseases were negative for the myofibroblast marker alpha-smooth muscle actin, suggesting a relatively undifferentiated phenotype. Taken together, these data suggest that fibrocytes are involved in the pathogenesis of human lung fibrosis.

IL-13 is pivotal in the fibro-obliterative process of bronchiolitis obliterans syndrome.

Acute allograft rejection is considered to be a predominately type 1 immune mediated response to the donor alloantigen. However, the type 2 immune mediated response has been implicated in multiple fibroproliferative diseases. Based on the fibro-obliterative lesion found during bronchiolitis obliterans syndrome (BOS), we hypothesized that the type 2 immune mediated response is involved in chronic lung allograft rejection. Specifically, whereas acute rejection is, in part, a type 1 immune response, chronic rejection is, in part, a type 2 immune response. We found the type 2 cytokine, IL-13, to be elevated and biologically active in human bronchoalveolar lavage fluid during BOS. Translational studies using a murine model of BOS demonstrated increased expression of IL-13 and its receptors that paralleled fibro-obliteration. In addition, in vivo neutralization of IL-13 reduced airway allograft matrix deposition and murine BOS, by a mechanism that was independent of IL-4. Furthermore, using IL-13Ralpha2(-/-) mice, we found increased fibro-obliteration. Moreover, anti-IL-13 therapy in combination with cyclosporin A had profound effects on reducing murine BOS. This supports the notion that IL-13 biological axis plays an important role during the pathogenesis of BOS independent of the IL-4 biological axis.

Idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF; also known as cryptogenic fibrosing alveolitis) is a distinctive type of chronic fibrosing interstitial pneumonia of unknown cause associated with the histological pattern usual interstitial pneumonia (UIP). UIP is a distinct histological pattern observed in IPF but may also be found in other etiologies. The diagnosis of UIP can be established by surgical lung biopsy or by high-resolution thin-section CT scans (provided the radiographic features are classical). Historically, patients labeled as 'IPF' encompassed a group of disorders, including UIP, as well as other idiopathic interstitial pneumonias, which differ from UIP in prognosis and responsiveness to therapy. The term IPF should be restricted to patients with idiopathic UIP. The inciting cause(s) and pathogenesis of IPF have not been elucidated but alveolar epithelial cell injury and dysregulation or altered phenotypic expression of fibroblasts are key elements. Inflammatory cells may play minor roles in initiating or propagating the fibrotic process. The prognosis of idiopathic UIP is poor. Mean survival following diagnosis approximates at 3 years. Current medical therapies are of unproven value. Lung transplantation is a viable option for patients failing medical therapy.

Usual interstitial pneumonia.

Usual interstitial pneumonia (UIP) is a distinct histological lesion observed in idiopathic pulmonary fibrosis (IPF) but can be found in other etiologies. The diagnosis of UIP can be established by surgical lung biopsy or by high-resolution thin-section computed tomographic (CT) scans (provided the radiographic features are classical). Historically, patients labeled as "IPF" encompassed a group of disorders, including UIP as well as other idiopathic interstitial pneumonias that differ from UIP in prognosis and responsiveness to therapy. Current recommendations from international consensus statements restrict the term IPF to patients with idiopathic UIP. The inciting cause(s) and pathogenesis of UIP have not been elucidated, but alveolar epithelial cell injury and dysregulation or altered phenotypic expression of fibroblasts are key elements. Inflammatory cells may play minor roles in initiating or propagating the fibrotic process. The prognosis of UIP is poor. Mean survival following diagnosis approximates 3 years. Current therapies are of unproven value. Corticosteroids or immunosuppressive agents have been most often used, but data affirming benefit are lacking. Lung transplantation is a viable option for patients failing medical therapy. This review discusses diagnostic criteria for UIP (both histopathological and radiographic), natural history and clinical course, and therapeutic approaches (both current and future).

Transbronchial biopsy in usual interstitial pneumonia.

BACKGROUND: Usual interstitial pneumonia (UIP) is a slowly progressive, usually fatal form of idiopathic interstitial pneumonia for which there is no effective treatment. Transbronchial biopsy (TBB) has been utilized only to exclude other diseases such as sarcoidosis, lymphangitic carcinoma, and infection, for example, but TBB is generally considered to have little role in confirming UIP. OBJECTIVE: To determine whether diagnostic changes of UIP can be appreciated on TBB specimens. DESIGN: Retrospective analysis of TBB specimens from patients with proven UIP. SETTING: Two study sites in the United States. PARTICIPANTS: Twenty-one patients with UIP confirmed by surgical lung biopsy and/or lung explant, and 1 patient with UIP confirmed by clinical and radiographic findings along with follow-up information. MEASUREMENTS AND RESULTS: Adequate tissue for diagnosis was available in 18 cases; in 7 cases (32% overall), there were varying combinations of interstitial fibrosis in a patchwork pattern along with fibroblast foci and/or honeycomb change. These features were considered diagnostic of UIP. Interstitial fibrosis along with fibroblast foci or honeycomb change were seen in two other cases, but the fibrosis lacked a patchwork pattern, and these features were considered consistent with UIP. Nonspecific interstitial fibrosis alone was found in nine cases. CONCLUSIONS: In summary, characteristic histologic features of UIP can be identified on TBB specimens more often than previously appreciated. TBB may be more useful in confirming UIP than previously recognized.

Pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic fibrosing lung disease limited to the lungs and associated with the histologic appearance of usual interstitial pneumonia (UIP) on surgical lung biopsy. The estimated prevalence in the United States is between 35,000 and 55,000 cases,and evidence suggests that the prevalence is increasing for IPF. Risk factors associated with pulmonary fibrosis include smoking, environmental exposures, gastroesophageal reflux dis-ease, commonly prescribed drugs, diabetes mellitus, infectious agents, and genetic factors. The diagnosis requires a careful history and physical examination, characteristic physiological and radiological studies, and, in some cases, a surgical lung biopsy. The natural history of IPF is not known, but evidence supports the concept of a continuum of idiopathic interstitial pneumonias that may overlap in time. Most patients with IPF succumb to respiratory failure, cardiovascular disease, lung cancer, pulmonary embolism, infection, and other health problems. The median survival time for patients with IPF is less than 3 yr. Factors that predict poor outcome include older age, male gender, severe dyspnea, history of cigarette smoking, severe loss of lung function, appearance and severity of fibrosis on radiological studies, lack of response to therapy,and prominent fibroblastic foci on histopathologic evaluation. Conventional therapy (corticosteroids, azathioprine, cyclophosphamide) provides only marginal benefit. Lung transplantation should be considered for patients with IPF refractory to medical therapy. In light of the poor prognosis and lack of response to available anti-inflammatory therapy, alternative approaches to therapy are being pursued. Emerging strategies to treat patients with IPF include agents that inhibit epithelial injury or enhance repair, anti-cytokine approaches, agents that inhibit fibroblast proliferation or induce fibroblast apoptosis, and other novel approaches.

CXCL11 attenuates bleomycin-induced pulmonary fibrosis via inhibition of vascular remodeling.

Aberrant vascular remodeling is a central hallmark for the development and progression of idiopathic pulmonary fibrosis. The mechanisms underlying the pathophysiologic alterations, however, are poorly understood. A recent phase II trial of interferon gamma-1b has demonstrated a trend toward a decrease in profibrotic and proangiogenic biologic markers, and upregulation of lung CXCL11 mRNA and bronchoalveolar lavage fluid and plasma protein levels of CXCL11. We hypothesized that net aberrant vascular remodeling seen during the pathogenesis of fibroplasia and deposition of extracellular matrix during bleomycin-induced pulmonary fibrosis can be attenuated by treatment with the angiostatic ELR(-) CXC chemokine, CXCL11. In a preclinical model, systemic administration of CXCL11 reduced pulmonary collagen deposition, procollagen gene expression, and histopathologic fibroplasia and extracellular matrix deposition in the lung of bleomycin-treated mice. CXCL11 treatment significantly reduced bleomycin-induced pulmonary fibrosis without altering specific lung leukocyte populations. CXCR3 is not expressed on fibroblasts and CXCL11 had no direct functional effect on pulmonary fibroblasts. The angiogenic activity in the lung was significantly decreased, however, and CXCL11 treatment reduced the total number of endothelial cells in the lung following bleomycin exposure. The results suggest that CXCL11 inhibits pulmonary fibrosis by altering aberrant vascular remodeling.