The role of gastroesophageal reflux in idiopathic pulmonary fibrosis

Mendelian randomization study on the causal effect of herpes simplex virus infection on idiopathic pulmonary fibrosis

BACKGROUND

Previous observational studies have shown that past infection of herpes simplex virus (HSV) is associated with idiopathic pulmonary fibrosis (IPF). The present study aims to identify the causal link between HSV infection (exposure factor) and IPF (outcome factor).

RESEARCH DESIGN AND METHODS

To date, the largest publicly available genome-wide association study (GWAS) for HSV infection (1,595 cases and 211,856 controls from Finnish ancestry) and for IPF (1,028 cases and 196,986 controls from Finnish ancestry) were used to perform this two-sample Mendelian randomization (MR) study.

RESULTS

We found no significant pleiotropy or heterogeneity of all selected nine HSV infection-associated genetic instrumental variants (IVs) in IPF GWAS dataset. Interestingly, we found that as HSV infection genetically increased, IPF risk increased based on an inverse-variance weighted (IVW) analysis (odds ratio [OR] = 1.280, 95% confidence interval [CI]: 1.048-1.563; p = 0.015) and weighted median (OR = 1.321, 95% CI: 1.032-1.692; p = 0.027).

CONCLUSIONS

Our analysis suggests a causal effect of genetically increased HSV infection on IPF risk. Thus, HSV infection may be a potential risk factor for IPF.

Treatment of idiopathic pulmonary fibrosis and progressive pulmonary fibrosis: A position statement from the Thoracic Society of Australia and New Zealand 2023 revision

Idiopathic pulmonary fibrosis (IPF) is a progressive disease leading to significant morbidity and mortality. In 2017 the Thoracic Society of Australia and New Zealand (TSANZ) and Lung Foundation Australia (LFA) published a position statement on the treatment of IPF. Since that time, subsidized anti-fibrotic therapy in the form of pirfenidone and nintedanib is now available in both Australia and New Zealand. More recently, evidence has been published in support of nintedanib for non-IPF progressive pulmonary fibrosis (PPF). Additionally, there have been numerous publications relating to the non-pharmacologic management of IPF and PPF. This 2023 update to the position statement for treatment of IPF summarizes developments since 2017 and reaffirms the importance of a multi-faceted approach to the management of IPF and progressive pulmonary fibrosis.

The causal relationship between gastro-oesophageal reflux disease and idiopathic pulmonary fibrosis: a bidirectional two-sample Mendelian randomisation study

BACKGROUND

Gastro-oesophageal reflux disease (GORD) is associated with idiopathic pulmonary fibrosis (IPF) in observational studies. It is not known if this association arises because GORD causes IPF or because IPF causes GORD, or because of confounding by factors, such as smoking, associated with both GORD and IPF. We used bidirectional Mendelian randomisation (MR), where genetic variants are used as instrumental variables to address issues of confounding and reverse causation, to examine how, if at all, GORD and IPF are causally related.

METHODS

A bidirectional two-sample MR was performed to estimate the causal effect of GORD on IPF risk and of IPF on GORD risk, using genetic data from the largest GORD (78 707 cases and 288 734 controls) and IPF (4125 cases and 20 464 controls) genome-wide association meta-analyses currently available.

RESULTS

GORD increased the risk of IPF, with an OR of 1.6 (95% CI 1.04-2.49; p=0.032). There was no evidence of a causal effect of IPF on the risk of GORD, with an OR of 0.999 (95% CI 0.997-1.000; p=0.245).

CONCLUSIONS

We found that GORD increases the risk of IPF, but found no evidence that IPF increases the risk of GORD. GORD should be considered in future studies of IPF risk and interest in it as a potential therapeutic target should be renewed. The mechanisms underlying the effect of GORD on IPF should also be investigated.

Rethinking Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a devastating disease for patients and their loved ones. Since initial efforts to characterize this disease in the 1960s, understanding of IPF has evolved considerably. Such evolution has continually challenged prior diagnostic and treatment paradigms, ushering in an era of higher confidence diagnoses with less invasive procedures and more effective treatments. This review details how research and clinical experience over the past half century have led to a rethinking of IPF. Here, the evolution in understanding of IPF pathogenesis, diagnostic evaluation and treatment approach is discussed.

Obstructive sleep apnea in pulmonary fibrosis

PURPOSE OF REVIEW

In previous years, there was limited research related to the role of sleep in interstitial lung diseases (ILDs). Physicians treating ILD patients tended to focus mainly on the daily disabling symptoms overlooking the possible significant role of coexisting sleep disorders, such as obstructive sleep apnea (OSA). However, recently, there has been a growing interest in OSA in ILDs, as well as OSA effect on sleep, life quality and outcome in these patients with emphasis on idiopathic pulmonary fibrosis (IPF).

RECENT FINDINGS

OSA has been recognized as an important, high-prevalence comorbidity for the diagnosis and management of IPF. This publication provides a summary of the most relevant recent evidence with regard to OSA in various ILDs and especially IPF, including prevalence, clinical presentation, complications, screening and diagnosis. It also provides updated evidence on the role of OSA therapy in improving sleep, quality of life and disease outcome.

SUMMARY

It is too early to characterize OSA and ILDs association as an 'overlap' syndrome. In depth research is needed, including studies with large numbers of ILDs and IPF patients. The main priority is to increase the awareness among physicians for early diagnosis of OSA in ILDs patients.

The prevalence of obstructive sleep apnea in interstitial lung disease: a systematic review and meta-analysis

PURPOSE

To evaluate the overall prevalence of obstructive sleep apnea (OSA) in interstitial lung disease (ILD).

METHODS

We performed a systematic search of the academic literature while adhering to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines on four scientific databases including EMBASE, CENTRAL, Scopus, and MEDLINE. We performed a meta-analysis to evaluate the prevalence and severity of OSA. Severity was defined by apnea-hypopnea index (AHI) as mild (AHI ≥ 5 to < 15/h), moderate (AHI ≥ 15 to < 30/h), and severe (AHI ≥ 30/h).

RESULTS

From 1397 studies, we found 10 eligible studies with 569 patients with ILD (mean age: 65.3 ± 6.0 years). Among these patients, 332 (61%) suffered from OSA with 32% categorized as mild, 17% moderate, and 9% severe.  CONCLUSION: This systematic review and meta-analysis provides preliminary evidence regarding the high prevalence of OSA in ILD.

Anti-MDA5 Antibody-positive Clinically Amyopathic Dermatomyositis Complicated by Unilateral Right-sided Interstitial Lung Disease

We herein report a case of anti-MDA5 antibody-positive, clinically amyopathic dermatomyositis complicated by unilateral interstitial lung disease (ILD) in a 78-year-old man with a history of left lung tumor resection. He was admitted due to a persistent fever and abnormal right pulmonary opacity. A transbronchial lung cryobiopsy revealed pulmonary fibrosis, and combined immunosuppressive therapy was initiated. Findings from multiple evaluations, including dynamic breathing magnetic resonance imaging, supported decreased perfusion, ventilation, and mobility of the left lung as etiological factors of unilateral lung ILD. When patients present with laterality of such findings, clinicians should be aware that atypical imaging findings may be observed.

Comorbidities in idiopathic pulmonary fibrosis: an underestimated issue

Idiopathic pulmonary fibrosis (IPF) is a progressive and fibrosing lung disease with a poor prognosis. Between 60% and 70% of IPF patients die of IPF; the remaining causes of death may be due to comorbidities occurring in this ageing population. Interest in the role played by comorbidities in IPF has increased in the past few years. The optimal clinical management of IPF is multifaceted and not only involves antifibrotic treatment, but also vaccinations, oxygen supplementation, evaluation of nutritional status as well as psychological support and patient education. Symptom management, pulmonary rehabilitation, palliative care and treatment of comorbidities represent further areas of clinical intervention. This review analyses the major comorbidities observed in IPF, focusing on those that have the greatest impact on mortality and quality of life (QoL). The identification and treatment of comorbidities may help to improve patients' health-related QoL (i.e. sleep apnoea and depression), while some comorbidities (i.e. lung cancer, cardiovascular diseases and pulmonary hypertension) influence survival. It has been outlined that gathering comorbidities data improves the prediction of survival beyond the clinical and physiological parameters of IPF.

Intermittent Hypoxia Increases the Severity of Bleomycin-Induced Lung Injury in Mice

Background

Severe obstructive sleep apnea (OSA) with chronic intermittent hypoxia (IH) is common in idiopathic pulmonary fibrosis (IPF). Here, we evaluated the impact of IH on bleomycin- (BLM-) induced pulmonary fibrosis in mice.

Methods

C57BL/6J mice received intratracheal BLM or saline and were exposed to IH (40 cycles/hour; FiO₂ nadir: 6%; 8 hours/day) or intermittent air (IA). In the four experimental groups, we evaluated (i) survival; (ii) alveolar inflammation, pulmonary edema, lung oxidative stress, and antioxidant enzymes; (iii) lung cell apoptosis; and (iv) pulmonary fibrosis.

Results

Survival at day 21 was lower in the BLM-IH group (p < 0.05). Pulmonary fibrosis was more severe at day 21 in BLM-IH mice, as assessed by lung collagen content (p = 0.02) and histology. At day 4, BLM-IH mice developed a more severe neutrophilic alveolitis, (p < 0.001). Lung oxidative stress was observed, and superoxide dismutase and glutathione peroxidase expression was decreased in BLM-IH mice (p < 0.05 versus BLM-IA group). At day 8, pulmonary edema was observed and lung cell apoptosis was increased in the BLM-IH group.

Conclusion

These results show that exposure to chronic IH increases mortality, lung inflammation, and lung fibrosis in BLM-treated mice. This study raises the question of the worsening impact of severe OSA in IPF patients.

Towards a global initiative for fibrosis treatment (GIFT)

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease characterised by increased scarring of lung tissue. Despite the recent introduction of novel drugs that slow disease progression, IPF remains a deadly disease, and the benefits of these new drugs differ markedly between patients.

Human diseases arise due to alterations in an almost limitless network of interconnected genes, proteins, metabolites, cells and tissues, in direct relationship with a continuously changing macro- or microenvironment. Systems biology is a novel research strategy that seeks to understand the structure and behaviour of the so-called “emergent properties” of complex systems, such as those involved in disease pathogenesis, which are most often overlooked when just one element of disease pathogenesis is observed in isolation.

This article summarises the debate that took place during a European Respiratory Society research seminar in Barcelona, Spain on December 15–16, 2016, which focused on how systems biology could generate new data by integrating the different IPF pathogenic levels of complexity. The main conclusion of the seminar was to create a global initiative to improve IPF outcomes by integrating cutting-edge international research that leverages systems biology to develop a precision medicine approach to tackle this devastating disease.

A novel call to action for implementing systems biology in IPF researchhttp://ow.ly/Is0A30gpnVb

Obstructive sleep apnoea and related comorbidities in incident idiopathic pulmonary fibrosis

The objectives of this prospective study were: 1) to determine the prevalence and determinants of obstructive sleep apnoea (OSA) in patients with newly diagnosed idiopathic pulmonary fibrosis (IPF); 2) to determine whether OSA was associated with cardiovascular disease (CVD) as well as increased oxidative stress and levels of IPF biomarkers in the blood.

A group of 45 patients with newly diagnosed IPF attended polysomnography. The prevalence of CVD and the severity of coronary artery calcification were investigated by high-resolution computed tomography. The levels of 8-hydroxydeoxyguanosine (8-OH-DG) and various IPF biomarkers in the blood were compared between patients with no or mild OSA (apnoea–hypopnoea index (AHI) <15 events·h−1), with moderate OSA (15 ≤AHI <30 events·h−1) and with severe OSA (AHI ≥30 events·h−1).

The prevalence of moderate-to-severe OSA and severe OSA was 62% and 40%, respectively. AHI did not correlate with demographic or physiological data. All patients with severe OSA had a medical history of CVD,versus41.2% and 40% of those with no or mild OSA, or with moderate OSA, respectively (p<0.0001). Ischaemic heart disease (IHD) and moderate-to-severe coronary artery calcifications were strongly associated with severe OSA. The 8-OH-DG and matrix metalloproteinase-7 serum levels were significantly increased in the severe OSA group.

Moderate-to-severe OSA is highly prevalent in incident IPF and severe OSA is strongly associated with the presence of CVD, particularly IHD.

Diagnostic and prognostic challenges in Idiopathic Pulmonary Fibrosis: A patient's "Q and A" approach

Idiopathic Pulmonary Fibrosis (IPF) is a chronic, progressive, debilitating disease of unknown etiology that leads to death nearly half of the patients within 3-3.5 years. The past 15 years, the scientific community has made tremendous progress towards standardized diagnostic and prognostic algorithms that led to the generation of the 2011 ATS/ERS/JRS/ALAT guidelines. The latest guidelines provided us with fundamental diagnostic algorithms that set the diagnosis in the majority of cases; however, they leave a significant minority of patients without diagnostic and most importantly, therapeutic umbrella. To this end current guidelines should be revisited in light of research advances, including the tools of "fibromics" and at the same time provide practical guidance to the real-world of IPF in order to address patients' needs. The scope of this review article is to summarize challenges in the everyday IPF clinical practice and make an effort to provide realistic answers to patients' questions.

Computed Tomography of the Esophagus in Scleroderma and Lung Disease

Systemic sclerosis, or scleroderma, is a collagen vascular disease characterized by hardening of the skin and involvement of internal organs, most commonly the esophagus. The most frequent cause of death in these patients is lung disease. Esophageal dysfunction has been implicated in the pathogenesis of interstitial lung disease. We previously developed a standard for the esophageal diameter on chest computed tomography (CT) and hypothesized that patients with esophageal dilation would be more likely to have interstitial lung disease than those without. In this study, we test this in 121 systemic sclerosis patients with interstitial lung disease and 48 of those without interstitial lung disease. For controls, we evaluated 121 patients followed at a general pulmonary clinic and the previously studied normal healthy standards. This study demonstrated that esophageal dilation is common in systemic sclerosis patients (66.3% for the maximal esophageal diameter more than or equal to 15 mm), that systemic sclerosis patients with interstitial lung disease have more dilated esophagi than those without interstitial lung disease (median 19.4 mm vs. 14.1 mm), and that esophageal parameters are negatively correlated with pulmonary function. We also found that patients from general pulmonary clinic were more likely to have dilated esophagi than normal controls (median 12.1 mm vs. 9.7 mm). The CT measurement of esophageal diameter may be a useful marker of patients at risk for developing lung disease.

Identification and treatment of comorbidities in idiopathic pulmonary fibrosis and other fibrotic lung diseases

PURPOSE OF REVIEW

The interstitial lung diseases (ILDs) frequently result in considerable disability and reduced survival in affected patients. Unfortunately, they are often poorly responsive to available therapies. Comorbidities, both pulmonary and nonpulmonary, frequently accompany ILDs and contribute to adverse outcomes.

RECENT FINDINGS

Multiple comorbidities, including gastroesophageal reflux disease, venous thromboembolism, coronary artery disease, sleep-disordered breathing, depression, emphysema, pulmonary hypertension, and lung cancer contribute to the morbidity and mortality of fibrotic lung disease.

SUMMARY

The identification and treatment of comorbidities may improve morbidity and potentially impact mortality in patients with ILD. A high index of suspicion and an awareness of the spectrum of comorbidities are important in optimizing outcomes in this group of patients.

Bronchoalveolar pH and inflammatory biomarkers in newly diagnosed IPF and GERD patients: a case-control study

Background

Several studies have suggested that idiopathic pulmonary fibrosis (IPF) may be related to repeated aspiration of gastric contents over long periods of time. We aimed to investigate differences between pH measured directly in the lung, and biomarkers of acute inflammation in patients with newly diagnosed IPF and in patients with newly diagnosed GERD.

Material/Methods

All subjects (N=61) underwent collection of medical history, physical examination, pulmonary function testing, bronchoscopy, endoscopy, arterial blood gas analyses, and biochemical testing.

Results

Previously diagnosed GERD was found in 56.7%, typical symptoms of reflux in 80%, and Helicobacter pylori in gastric biopsy specimens in 76.6% of the cases. pH in peripheral branches of bronchi in the cases was 5.32±0.44 and was 6.27±0.31 (p<0.001) in the control group. The average values of LDH, ALP, and CRP in bronchoalveolar aspirate and in serum, as well as TNF-α in bronchoalveolar aspirate, were significantly higher in IPF patients.

Conclusions

The more acidic environment in the bronchoalveolar aspirate of the IPF subjects could contribute to the development or progression of IPF, possibly via changes in local metabolism or by damaging local cells and tissue. However, further studies with larger numbers of patients are required to clarify the role of gastric fluid aspiration in IPF pathogenesis. Our preliminary work has identified inflammatory biomarkers LDH, ALP, and TNF-α as potentially important in the pathologic processes in IPF. Further research is needed to determine their importance in clinical intervention and patient care.

Preoperative diagnostic workup before antireflux surgery: an evidence and experience-based consensus of the Esophageal Diagnostic Advisory Panel

BACKGROUND

Gastroesophageal reflux disease (GERD) is a very prevalent disorder. Medical therapy improves symptoms in some but not all patients. Antireflux surgery is an excellent option for patients with persistent symptoms such as regurgitation, as well as for those with complete symptomatic resolution on acid-suppressive therapy. However, proper patient selection is critical to achieve excellent outcomes.

STUDY DESIGN

A panel of experts was assembled to review data and personal experience with regard to appropriate preoperative evaluation for antireflux surgery and to construct an evidence and experience-based consensus that has practical application.

RESULTS

The presence of reflux symptoms alone is not sufficient to support a diagnosis of GERD before antireflux surgery. Esophageal objective testing is required to physiologically and anatomically evaluate the presence and severity of GERD in all patients being considered for surgical intervention. It is critical to document the presence of abnormal distal esophageal acid exposure, especially when antireflux surgery is considered, and reflux-related symptoms should be severe enough to outweigh the potential side effects of fundoplication. Each testing modality has a specific role in the diagnosis and workup of GERD, and no single test alone can provide the entire clinical picture. Results of testing are combined to document the presence and extent of the disease and assist in planning the operative approach.

CONCLUSIONS

Currently, upper endoscopy, barium esophagram, pH testing, and manometry are required for preoperative workup for antireflux surgery. Additional studies with long-term follow-up are required to evaluate the diagnostic and therapeutic benefit of new technologies, such as oropharyngeal pH testing, multichannel intraluminal impedance, and hypopharyngeal multichannel intraluminal impedance, in the context of patient selection for antireflux surgery.

Respiratory Diseases

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Pulmonary arteriovenous fistulas have congenital and hereditary etiology, and patients are at risk for life-threatening rupture requiring surgery.

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Wegener's granulomatosis can affect any organ system, although renal and pulmonary involvement is most common; men ages 40 to 50 are at increased risk.

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Lymphomatoid granulomatosis affects cardiopulmonary, neurologic, and myeloproliferative systems; may result from opportunistic infection, and frequently progresses to lymphoma; men age 50 to 60 are at increased risk. Spontaneous remission occurs in some cases; mortality is 60% to 90% at 5 years.

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Churg-Strauss syndrome is usually associated with long-standing asthma, with men and women affected equally, and can affect any organ system; major cause of death is cardiac related.

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Primary pulmonary hypertension is a diagnosis of exclusion; women are affected twice as likely as men; right-to-left shunt may occur in 30%, secondary to patent foramen ovale; hypoxia with resultant heart failure is typical cause of death.

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Cystic fibrosis is an autosomal recessive disease, eventually fatal, with increased risk for airway obstruction, fluctuating pulmonary function, and chronic hypoxia; risk for spontaneous pneumothorax is 20%.

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Bronchiolitis obliterans organizing pneumonia is a pulmonary obstructive disease that may be reversible and usually resolves spontaneously.

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Idiopathic pulmonary hemosiderosis is associated with autoimmune disorders; patients have recurrent hemorrhage, pulmonary fibrosis, restrictive lung disease, and pulmonary hypertension, with some cases of spontaneous remission.

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Chronic eosinophilic pneumonia may be preceded by adult-onset asthma; women are at increased risk; prognosis is good.

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Goodpasture's syndrome is a genetic autoimmune disorder involving the pulmonary and renal systems.

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Pulmonary alveolar proteinosis, a lipoprotein-rich accumulation in alveoli, has three forms: congenital, decreased alveolar macrophage activity, and idiopathic; some cases of spontaneous remission occur.

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Sarcoidosis may affect any organ system; African American, northern European, and females are at greater risk; many patients are asymptomatic.

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Systemic lupus erythematosus may affect any organ system; women of childbearing age are at increased risk.

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Idiopathic pulmonary fibrosis is a rare interstitial lung disease, with smokers at increased risk for pulmonary malignancy; survival is usually 2 to 3 years from diagnosis; no effective treatment exists, with lung transplant the only therapeutic option.

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Acute respiratory distress syndrome (ARDS) is associated with underlying critical illness or injury, developing acutely in 1 to 2 days; mortality is 25% to 35%.

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Pulmonary histiocytosis X is an interstitial lung disease associated with cigarette smoking and an unpredictable course; some spontaneous remission occurs.

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Lymphangioleiomyomatosis involves progressive deterioration of lung function, associated with tuberous sclerosis and exacerbated by pregnancy, with women at increased risk; possible spontaneous pneumothorax and chylothorax; death usually results from respiratory failure.

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Ankylosing spondylitis is a genetic inflammatory process resulting in fusion of axial skeleton and spinal deformities, with men at increased risk; radiologic bamboo spine, sacral to cervical progression, and restrictive lung disease with high reliance on diaphragm; extraskeletal manifestations may occur.

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Kyphosis (exaggerated anterior flexion) and scoliosis (lateral rotational deformity) are spinal/rib cage deformities with idiopathic, congenital, or neuromuscular etiology; corrective surgery done if Cobb thoracic angle >50% lumbar angle >40%.

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Bleomycin is an antineoplastic antibiotic used in combination chemotherapy, with no myelosuppressive effect; toxicity can cause life-threatening pulmonary fibrosis.

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Influenza A is highly infectious, presenting with flulike symptoms and possible progression to ARDS; human-to-human exposure is through droplets or contaminated surfaces, with high risk for infants, children, pregnancy, chronically ill, or renal replacement therapy patients. No prophylactic treatment exists; treat patients with high index of suspicion without definitive testing; rRT-PCR and viral cultures are sensitive for pandemic H1N1 strain.

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Severe acute respiratory syndrome (SARS) is highly infectious, transmitted by coronavirus with human-to-human exposure via droplets or surfaces, and may progress to ARDS.

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Echinococcal disease of lung is from canine tapeworm, transmitted by eggs from feces; rupture of cyst may result in anaphylactic reaction or spread of disease to other organs; children are at increased risk. No transthoracic needle aspiration is done; surgery is only option.

[Bronchopulmonary manifestations of gastroesophageal reflux disease]

Gastroesophageal reflux disease (GERD) is a common disease in the western world. Usually it occurs with typical symptoms like heartburn and regurgitation, but almost every third GERD-patient presents with extraesophageal symptoms and diseases in which a causal relation with GERD is discussed. The extraesophageal symptoms possibly associated with GERD are chronic cough, bronchial asthma, sleep disturbances including obstructive sleep apnea, hoarseness, dental erosions, non-cardiac chest pain and idiopathic pulmonary fibrosis. This article gives an overview of the reflux-associated diseases of the airways as well as the proposed pathomechanisms and therapeutic options.

Reflux-induced collagen type v sensitization: potential mediator of bronchiolitis obliterans syndrome

BACKGROUND

Lung transplantation continues to have poor long-term survival partly because of the high incidence of bronchiolitis obliterans syndrome (BOS). Gastroesophageal reflux disease (GERD) has been implicated in BOS pathogenesis. We investigated the role of collagen type V [col(V)] sensitization in this process.

METHODS

Only primary lung transplant recipients were included. Reflux status was assessed with pH monitoring, impedance plethysmography, and esophagogastroduodenoscopy. Sensitivity to col(V) was determined with trans vivo delayed-type hypersensitivity reaction (DTH). Kaplan-Meier analyses were performed.

RESULTS

Of the 54 recipients, 26 had proven GERD. There were no significant between-group differences in diagnosis; donor and recipient age; sex; ischemic time; single vs bilateral; human leukocyte antigen A, B, and DR matching cytomegalovirus status; acute rejections; or mean follow-up period. The mean DTH response in the GERD group was 25.7 x 10(-4) inches vs 18.3 x 10(-4) inches in the non-GERD group (P = .023). There was a significant reduction in BOS-free survival in the GERD group for both BOS-I (GERD+, 28.3%; GERD-, 86.6%; P = .0001) and BOS-II/III (GERD+, 66.2%; GERD-, 91.7%; P = .0374). A second cohort of 53 patients awaiting lung transplantation also was assayed. The mean DTH response in the GERD group was 24.0 x 10(-4) inches vs 13.1 x 10(-4) inches in the non-GERD group (P = .003). There were no differences in age or sex.

CONCLUSIONS

GERD is strongly associated with the development of BOS after primary lung transplantation. Col(V) sensitization is associated with reflux and BOS and may play an intermediary role in the pathogenesis of BOS. Trials using col(V) reactivity to assess the impact of antireflux procedures in patients with lung transplantation and idiopathic pulmonary fibrosis are warranted.

Does chronic microaspiration cause idiopathic pulmonary fibrosis?

Idiopathic pulmonary fibrosis is a diffuse fibrotic lung disease of unknown etiology with no effective treatment. Emerging data support a role for chronic microaspiration (ie, subclinical aspiration of small droplets) in the pathogenesis and natural history of idiopathic pulmonary fibrosis. However, the precise relationship between chronic microaspiration and idiopathic pulmonary fibrosis remains unknown. Gastroesophageal reflux, a presumed risk factor for microaspiration, has been strongly associated with idiopathic pulmonary fibrosis with an estimated prevalence of up to 90%. This review aims to describe the relationship between chronic microaspiration and idiopathic pulmonary fibrosis by laying out the clinical and biologic rationale for this relationship and exploring the scientific evidence available. The gaps in our current understanding of the diagnosis of chronic microaspiration and idiopathic pulmonary fibrosis and the ongoing uncertainties in management and treatment will be highlighted. Defining the role of chronic microaspiration in idiopathic pulmonary fibrosis is essential as it has potential clinical, pathobiological, and treatment implications for this deadly disease.

Obstructive sleep apnea is common in idiopathic pulmonary fibrosis

BACKGROUND

From 1984 to 2006, studies of sleep in patients with interstitial lung disease revealed disturbed sleep, frequent nocturnal desaturations, nocturnal cough, and obstructive sleep apnea (OSA). Our goal was to analyze OSA in an outpatient population of stable patients with idiopathic pulmonary fibrosis (IPF).

METHODS

Patients with IPF who had been followed up in the Vanderbilt Pulmonary Clinic were asked to participate. All patients were given a diagnosis of IPF by the 2000 American Thoracic Society consensus statement criteria. Subjects completed an Epworth sleepiness scale (ESS) questionnaire and a sleep apnea scale of sleep disorders questionnaire (SA-SDQ) before undergoing nocturnal polysomnography (NPSG). OSA was defined as an apnea-hypopnea index (AHI) of > 5 events per hour.

RESULTS

Fifty subjects enrolled and completed a NPSG. The mean age was 64.9 years, and the mean BMI was 32.3. OSA was diagnosed in 88% of subjects. Ten subjects (20%) had mild OSA (AHI, 5 to 15 events per hour), and 34 subjects (68%) had moderate-to-severe OSA (AHI, > 15 events per hour). Only 6 subjects (12%) had a normal AHI. One patient was asymptomatic as determined by ESS and SA-SDQ, but had an AHI of 24 events per hour. The sensitivity of the ESS was 75% with a specificity of 15%, whereas the SA-SDQ had a sensitivity of 88% with a specificity of 50%. BMI did not correlate strongly with AHI (r = 0.30; p = 0.05).

CONCLUSIONS

OSA is prevalent in patients with IPF and may be underrecognized by primary care providers and specialists. Neither ESS nor SA-SDQ alone or in combination was a strong screening tool. Given the high prevalence found in our sample, formal sleep evaluation and polysomnography should be considered in patients with IPF.

Does current knowledge explain the pathogenesis of idiopathic pulmonary fibrosis? A perspective

The cause of idiopathic pulmonary fibrosis (IPF) remains unknown. Although the observed biologic and biochemical processes associated with the disease are consistent with a fibrotic process, they are not necessarily unique to IPF. Furthermore, the importance of these observations will not be apparent until a directed therapy alters the natural history of the disease. There are essentially no studies that explain the unique histologic features of this disease. As mechanistic data accumulates, it is our opinion that these data should pass the test of explaining the clinical histologic features of the disease before it can be assumed that these features are unique for IPF.

Selective medicated (normal saline and exogenous surfactant) bronchoalveolar lavage in severe aspiration syndrome in children

OBJECTIVE

To study the ability of volume-controlled ventilation and medicated (normal saline plus surfactant) bronchoalveolar lavage in aspiration to reduce the duration of intubation and improve gas exchange.

DESIGN

: Randomized controlled clinical trial.

SETTING

Pediatric intensive care unit.

PATIENTS

Twenty children, 1 month to 16 yrs old, who were intubated and mechanically ventilated, were randomized within 6 hrs of aspiration to receive volume-controlled ventilation plus medicated bronchoalveolar lavage (treatment group) or the same ventilation and bronchosuction (control group).

INTERVENTIONS

Volume-controlled ventilation and positive end-expiratory pressure (10-12 cm H2O) were applied. Medicated bronchoalveolar lavage was performed using five aliquots of 5 mL of saline plus 10 mg/mL Curosurf (porcine surfactant, Chiesi Pharmaceutical SpA, Parma, Italy) in infants, five boluses of 10 mL of saline plus 5 mg/mL Curosurf in children, and four boluses of 25 mL of saline with 2.4 mg/mL Curosurf in adolescents for each affected lobe. One hour after bronchoalveolar lavage, 240 mg of Curosurf was administered locally.

MEASUREMENTS AND MAIN RESULTS

All patients survived. In the treatment group, days of intubation were 4.6 (+/-1.07), oxygenation index and Pao2/Fio2 improved significantly at 24 hrs, and statistical reduction in tidal volume mL/kg was observed from 36 hrs. In the control group, days of intubation were 11.8 (+/-3.22) (p < .0001), no improvement in oxygenation was noted, and pneumonia was observed in seven children (70%).

CONCLUSIONS

Even though this was an unblinded small clinical trial and low tidal volume strategy was not employed at an early stage after lung injury, there is some evidence that bronchoalveolar lavage with normal saline and surfactant may have clinical value in treating severe aspiration syndrome in children. More clinical studies are warranted to overcome study limitations and potential bias.

Diagnosis of interstitial lung diseases

Interstitial lung diseases (ILDs), a broad heterogeneous group of parenchymal lung disorders, can be classified into those with known and unknown causes. The definitions and diagnostic criteria for several major forms of ILDs have been revised in recent years. Although well over 100 distinct entities of ILDs are recognized, a limited number of disorders, including idiopathic pulmonary fibrosis, sarcoidosis, and connective tissue disease-related ILDs, account for most ILDs encountered clinically. In evaluating patients with suspected ILD, the clinician should confirm the presence of the disease and then try to determine its underlying cause or recognized clinicopathologic syndrome. Clues from the medical history along with the clinical context and radiologic findings provide the initial basis for prioritizing diagnostic possibilities for a patient with ILD. High-resolution computed tomography of the chest has become an invaluable tool in the diagnostic process. A confident diagnosis can sometimes be made on the basis of high-resolution computed tomography and clinical context. Serologic testing can be helpful in selected cases. Histopathologic findings procured through bronchoscopic or surgical lung biopsy are often needed in deriving a specific diagnosis. An accurate prognosis and optimal treatment strategy for patients with ILDs depend on an accurate diagnosis, one guided by recent advances in our understanding of the causes and pathogenetic mechanisms of ILDs.

A Clinicianʼs Guide to the Diagnosis and Treatment of Interstitial Lung Diseases

Interstitial lung disease (ILD) is a final common pathway for a large number of lung insults. It is characterized by progressive scarring of the lung leading to restriction and diminished oxygen transfer. Clinically, the presenting symptoms of ILD are nonspecific (cough and progressive dyspnea on exertion) and are often attributed to other diseases, thus delaying diagnosis and timely therapy. ILD occurs most commonly in older individuals and is increasingly encountered by internists. Both the diagnosis and treatment can be daunting: patients frequently have irreversibly impaired lung function at diagnosis, and therapeutic modalities are limited and associated with significant adverse effects. This review will assist internists in the recognition and management of ILD, provide a benchmark for pulmonary referrals, and offer guidance in advising patients with this life-threatening disorder.

Pepsin, a biomarker of gastric aspiration in lung allografts: a putative association with rejection

RATIONALE

Human lung transplantation is a therapeutic option for selected patients with advanced cardiopulmonary disease, but long-term survival is limited by chronic rejection. Persistent acute rejection and gastric aspiration have been implicated as risk factors but there is little or no evidence to date that they are associated.

OBJECTIVES

We have tested the hypothesis that pepsin, a marker of gastric aspiration, is present in lung transplant recipients, and that high levels are associated with biopsy-diagnosed acute rejection and/or bronchiolitis obliterans syndrome.

METHODS

Levels of bronchoalveolar lavage (BAL) pepsin were measured by ELISA in 36 lung transplant recipients, 4 normal volunteers, and 17 subjects with unexplained chronic cough.

MEASUREMENTS AND MAIN RESULTS

Our primary finding was that, compared with control subjects, BAL pepsin levels were elevated in stable lung transplant recipients, subjects with acute rejection, and subjects with bronchiolitis obliterans syndrome. Our secondary finding was that the highest levels were found in recipients with acute vascular rejection grade > or = A2 (median, 11.2; range, 5.4 - 51.7 ng/ml; normal median, 1.1; range, 0-2.3 ng/ml; p = 0.004).

CONCLUSIONS

We have shown that elevated levels of pepsin, a biomarker of gastric aspiration, are consistently identified in the BAL of lung allografts. The highest levels were seen in patients with > or = grade A2 acute rejection. This provides further evidence supporting the possible role of aspiration in the development of overall allograft injury.

Gastroesophageal reflux in patients with idiopathic pulmonary fibrosis referred for lung transplantation

OBJECTIVES

The association between gastroesophageal reflux disease and idiopathic pulmonary fibrosis has not been fully characterized. The aims of this study were to determine in patients with idiopathic pulmonary fibrosis (1) the prevalence of reflux symptoms, (2) the esophageal manometric profile, and (3) the prevalence of proximal and distal esophageal reflux.

METHODS

Between May 1999 and March 2006, 30 patients with idiopathic pulmonary fibrosis were referred to the Swallowing Center at the University of California San Francisco. Each patient underwent a structured symptom assessment, esophageal manometry, and 24-hour dual sensor ambulatory pH monitoring.

RESULTS

Twenty (67%) patients had abnormal esophageal reflux. Typical reflux symptoms, although more common in those with reflux, were not reliable as a screening test (sensitivity 65%, specificity 71%). Sixty-five percent of patients with abnormal reflux had a hypotensive lower esophageal sphincter. Abnormal esophageal peristalsis was more common among those with reflux (50% vs 10%; P = .03). In 9 (30%) patients, acid refluxed into the proximal esophagus for over 1% of the study time.

CONCLUSIONS

A majority of patients with idiopathic pulmonary fibrosis have pathologic reflux. Symptoms do not distinguish between those with and without reflux. In these patients, reflux is associated with a hypotensive lower esophageal sphincter and abnormal esophageal peristalsis, and often extends into the proximal esophagus.

Sole treatment of acid gastroesophageal reflux in idiopathic pulmonary fibrosis: a case series

RATIONALE

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal disease despite the available treatment regimes. Increased acid gastroesophageal reflux (GER) occurs in IPF patients.

OBJECTIVES

To follow the course of IPF in patients while being treated for acid GER alone.

METHODS

A retrospective review of the clinical outcomes of four patients with newly diagnosed IPF and increased acid GER who chose to be treated solely with anti-acid GER therapy were followed up regularly with pulmonary function tests (PFTs) [measuring FVC and the diffusing capacity of the lung for carbon monoxide] over a period of 2 to 6 years. Anti-acid GER therapy was administered using proton-pump inhibitors and fundoplication, if needed. Adequate suppression of acid GER was ascertained by 24-h esophageal pH monitoring.

MAIN RESULTS

PFT results in all four patients stabilized or improved while their conditions were maintained with adequate treatment for acid GER. All patients were alive at the last follow-up, and none manifested an acute exacerbation of IPF or needed treatment for respiratory problems during this period. After maintaining 4 years of improved status (based on PFT and exercise testing findings) while adhering to treatment for acid GER, one patient's deterioration correlated with poor compliance to daily treatment during the fifth year, although the PFT results at the sixth year showed stabilization compared to baseline values. The condition of another patient was stabilized by adhering to anti-acid GER treatment after an initial period of deterioration that was associated with nonadherence

CONCLUSIONS

Future clinical studies are indicated to clarify the role of acid GER in IPF and to determine whether adequate treatment for increased acid GER in part improves the outcome of patients with IPF.

Diffuse bronchiolar disease due to chronic occult aspiration

OBJECTIVE

To describe clinical, radiological, and histopathologic features of diffuse bronchiolar disease due to chronic occult aspiration.

PATIENTS AND METHODS

We identified 4 patients encountered from July 2001 to January 2004 who had persistent respiratory symptoms and lung Infiltrates and who were eventually diagnosed by surgical lung biopsy as having diffuse bronchiolar disease due to chronic occult aspiration. Medical records, radiological studies, and histopathologic specimens were reviewed to assess their clinicoradiologic presentation and diagnostic features.

RESULTS

The mean age of these 4 patients was 50 years (age range, 41-59 years), and 2 were women. All presented with persistent dyspnea, cough, and lung infiltrates. Three had a history of gastroesophageal reflux, but only 1 had active symptoms. Chest radiography showed interstitial infiltrates, whereas the predominant finding on computed tomography was numerous centrilobular nodules in all patients. Bronchoscopic lung biopsies had been performed in all patients, and the results were nondiagnostic. Surgical lung biopsy specimens revealed diagnostic features that consisted of bronchiolocentric organizing pneumonia with giant cells that contained material consistent with food in all 4 patients.

CONCLUSION

Diffuse bronchiolar disease likely represents an underrecognized form of aspiration-related lung disease and may occur in relatively young Individuals without symptoms suggestive of recurrent aspiration. Radiological features associated with this disorder are distinctively different from those seen in aspiration pneumonia.

Laparoscopic fundoplication in patients with end-stage lung disease awaiting transplantation

OBJECTIVE

There is a strong association between reflux and end-stage lung disease, especially idiopathic pulmonary fibrosis. The presence of reflux after lung transplantation might predispose to the development of bronchiolitis obliterans. We evaluated the risk and physiologic effect of laparoscopic fundoplication in patients on the lung transplant waiting list.

METHODS

One hundred forty-nine patients on the lung transplant waiting list between March 2001 and January 2005 were evaluated. Nineteen were found to have a history of reflux, continued symptoms, and severe reflux by means of pH and manometric studies and underwent laparoscopic fundoplication. The postoperative course of these 19 patients, including lung function, was retrospectively reviewed. Postoperatively, the lung function of the 14 patients with idiopathic pulmonary fibrosis who underwent the laparoscopic Nissen procedure was compared with that of 31 patients with idiopathic pulmonary fibrosis on the transplant waiting list who did not undergo fundoplication.

RESULTS

There were no perioperative complications and no decrease in lung function over the 15-month average follow-up. Exercise capacity remained stable, as determined on the basis of 6-minute walk distance. Patients with idiopathic pulmonary fibrosis treated with fundoplication had stable oxygen requirements, whereas control patients with idiopathic pulmonary fibrosis on the waiting list had a statistically significant deterioration in oxygen requirement.

CONCLUSIONS

Laparoscopic fundoplication can be performed safely in patients with end-stage lung disease awaiting lung transplantation. Overall, these patients maintained stable lung function during the follow-up period. When compared with a control group of patients with idiopathic pulmonary fibrosis not undergoing fundoplication, there was stabilization of oxygen requirement. A larger prospective trial evaluating the effect of laparoscopic fundoplication on underlying lung function in this patient population is warranted.

Chronic aspiration of gastric fluid accelerates pulmonary allograft dysfunction in a rat model of lung transplantation

OBJECTIVE

Emerging clinical evidence suggests that gastroesophageal reflux disease is associated with pulmonary allograft dysfunction. In this study, we used a model of rat lung transplantation to test the hypothesis that chronic aspiration of gastric contents accelerates pulmonary allograft dysfunction.

METHODS

We evaluated the effects of chronic aspiration on pulmonary isografts (strain F344) and pulmonary allografts (strain WKY to strain F344). Chronic aspiration consisted of 0.5 mL/kg of filtered gastric contents injected weekly into the left lung for 4 to 8 weeks beginning 1 week after transplantation. Seven days after the last aspiration, animals were killed, and grafts were evaluated grossly and by histologic and immunochemical analyses, including Masson trichrome staining for collagen and immunostaining for CD68+ and CD8+ cells. Serum cytokine concentrations were determined by bead-based immunoassays or enzyme-linked immunosorbent assay.

RESULTS

Allografts without aspiration (n = 12) demonstrated a relatively normal architecture with diffuse International Society for Heart and Lung Transplantation grade 3 acute rejection; occasional grade 4 rejection was noted. In contrast, allografts with chronic aspiration (n = 7) demonstrated severe grade 4 acute rejection with significant monocyte infiltration, fibrosis, and loss of normal alveolar anatomy. Grossly, 8 (67%) of 12 allografts without aspiration seemed to inflate and perfuse normally, whereas all allografts exposed to chronic aspiration were firm and shrunken, without the ability to ventilate (P = .013; Fisher exact test). Aspiration was associated with increases in graft-infiltrating macrophages and CD8+ T cells and higher levels of serum transforming growth factor beta.

CONCLUSIONS

Chronic aspiration of gastric contents promotes accelerated allograft failure and may promote a profibrotic environment.

Antireflux Surgery in the Setting of Lung Transplantation: Strategies for Treating Gastroesophageal Reflux Disease in a High-Risk Population

In lung transplant recipients, GERD is associated with increased incidence of acute rejection, earlier onset of chronic rejection, and higher mortality. Surgical treatment of GERD in lung recipients seems to prevent early allograft dysfunction and improve overall survival. A total (360 degrees) fundoplication is shown to be a safe and effective method for treating GERD in lung transplant recipients and is the authors' procedure of choice, in most cases, for this high-risk patient population. The principal goal should be to minimize reflux of enteric contents that may lead to micro- or macroaspiration events in this complicated group of patients. Perioperative care should involve a multidisciplinary approach, including physicians and other health care providers familiar with the complexities of lung transplant recipients.

Idiopathic pulmonary fibrosis: current trends in management

Idiopathic pulmonary fibrosis (IPF) is a chronic scarring illness limited to the lung and characterized by progressive dyspnea, restrictive pulmonary physiology, and radiographic diffuse lung disease. During the past few years, significant progress has been made, particularly in diagnosis: a stricter case definition has been outlined by consensus among international experts. Insights into the pathophysiology have revealed novel areas for therapeutic intervention. These advances have helped clarify many important diagnostic and therapeutic issues in this disease. An effective treatment regimen is yet to be determined. Significant new insights in the natural course and monitoring disease course have provided use of appropriate endpoints to test the safety and efficacy of new treatment regimens. Several multicenter clinical trials are underway and several more are being planned. It is hoped that ongoing molecular genetic studies and results of clinical trials will improve outcome of patients and families affected with this disease in the near future.