الفهرس 
Interstitial lung diseases in children
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Abstract
Definition
Interstitial lung disease (ILD) in infants and children represents a heterogeneous group of respiratory disorders that are mostly chronic and associated with high morbidity and mortality (around 15%) (Dinwiddie et al., 2002).
These disorders are characterized by inflammatory and fibrotic changes that affect alveolar walls.
Classification
Among the proposed classifications for pediatric ILD, one strategy frequently used is to separate the primary pulmonary disorders and the systemic disorders with pulmonary involvement. Recently, an additional group has been introduced which is based on the concept that some pediatric ILD are observed more frequently in infants, while others are more specific to older children.
Epidemiology
An estimated prevalence of 3.6 per million has been reported by Dinwiddie and coworkers through a national survey of chronic ILD in immunocompetent children in the United Kingdom and Ireland over a three year period (1995-1998) (Dinwiddie et al ., 2002).
Pathophysiology
• Critical role of the alveolar epithelium
The understanding of the mechanisms underlying the development and progression of ILD remains elusive.
(Clement & Eber ., 2008)
For a long time, chronic ILD and pulmonary fibrosis were believed to result mainly from chronic inflammation following an initial injury to the alveolar epithelial lining (Bringardner et al ., 2008)( Wells AU& Hogaboam CM ., 2008)
• Surfactant deficiency and stem cell dysfunction
It is now well established that surfactant dysfunction plays an important role in the development and progression of ILD.
Risk factors (Selman et al ., 2010)
Factors that may make one more susceptible to interstitial lung disease include:
• Age. Interstitial lung disease is much more likely to affect adults, although infants and children sometimes develop the disorder.
• Exposure to occupational and environmental toxins. If one works in mining, farming or construction or for any reason is exposed to pollutants known to damage his lungs, the risk of having interstitial lung disease greatly increases.
• Smoking. Some forms of interstitial lung disease are more likely to occur in people with a history of smoking, and active smoking may make the condition worse.
• Radiation and chemotherapy. Having radiation treatments to chest or using some chemotherapy drugs makes it more likely to develop lung disease.
• Oxygen. Continually inhaling very high levels of therapeutic oxygen for more than 48 hours can harm the lungs
Diagnosis of ILD
• Clinical presentation
The clinical manifestations vary from asymptomatic presentation with radiological features suggestive of ILD to more characteristic presence of respiratory symptoms and signs such as cough, tachypnea and exercise intolerance(Fauroux et al ., 2004) Common symptoms at presentation include cough, dyspnea, tachypnea and chest wall retraction, exercise limitation and frequent respiratory infections. Cough is observed in almost 75% of the patients, is usually non-productive and does not disturb sleep. Tachypnea is observed in 80% of patients and is usually the earliest and most common respiratory symptom.
The frequent clinical findings are inspiratory crackles (44%), tachypnea and retraction. In a child with a normal birth history, these are strongly suggestive of ILD. Other findings associated with an advanced stage of lung disease include finger clubbing (13%) and cyanosis during exercise or at rest (28%) (Clement ., 2004)
• Chest imaging
Plain radiographs are usually performed in a child suspected of ILD at first presentation
• High Resolution Computed Tomography (HRCT).
• Pulmonary function testing
• Bronchoalveolar lavage
• Tissue biopsies
Etiological diagnosis of ILD
A large number of pathological situations can impair gas exchange and contribute to progressive lung damage and ILD.
1) Exposure-related ILD; 2) systemic disease-associated ILD; 3) ILD specific to infancy.
Exposure related interstitial lung disease
Hypersensitivity pneumonitis
Medication, drug, radiation and tobacco exposure
Systemic disease-associated ILD
1- Connective tissues disease
The main disorders to be considered in childhood are rheumatoid arthritis, systemic sclerosis, and systemic lupus erythematosus.
2-Pulmonary vasculitis
• Wegener’s granulomatosis
• Churg-Strauss syndrome
3-sarcoidosis
4-Granulomatous diseases
5-Metabolic disorders
6-Lysosomal diseases
ILD specific to infancy
In the context of ILD, pulmonary interstitial glycogenosis, neuroendocrine cell hyperplasia, and chronic pneumonitis in infancy have been reported to be exclusively observed in very young children (Deutsch et al ., 2007)
Treatment
• General measures
Management of children with ILD includes administration of oxygen Immunization with influenza vaccine on an annual basis is recommended along with other routine immunizations against major respiratory pathogens. In addition,strict avoidance of tobacco smoke and other air pollutants.
• Pharmacologic therapy
In the majority of cases, treatment with immunosuppressive, anti-inflammatory, or anti-fibrotic drugs is required for weeks, months or even years (Fan et al ., 2004)
Among the anti-inflammatory agents used in pediatric ILD, steroids are the preferred choice.
An alternative to steroids is hydroxychloroquine .Individual case reports have described a response to hydroxychloroquine even in the presence of steroid resistance. In situations of inefficiency of steroids and hydroxychloroquine, other immunosuppressive or cytotoxic agents such as azathioprine, cyclophosphamide, cyclosporine, or methotrexate may be used.
• Other specific treatment strategies
These include whole lung lavage for pulmonary alveolar proteinosis, which has been reported to be effective by removing the material from the alveolar space . GM-CSF has also been shown of interest in this disease .Other strategies such as interferon-α for pulmonary haemangiomatosis are effective .
In recent years, lung transplantation has emerged as a viable option in children of all ages, even in young infants .
Complications (Shih ., et al 2011)
Interstitial lung disease can lead to a series of lifethreatening complications, including:
• High blood pressure in lungs (pulmonary hypertension)
Unlike systemic high blood pressure, this condition affects only the arteries in the lungs. It begins when scar tissue restricts the smallest blood vessels, limiting blood flow in the lungs. This in turn raises pressure within the pulmonary arteries. Pulmonary hypertension is a serious illness that becomes progressively worse.
• Right-sided heart failure (corpulmonale). This serious condition occurs when the heart’s lower right chamber (right ventricle) — which is less muscular than the left — has to pump harder than usual to move blood through obstructed pulmonary arteries. Eventually the right ventricle fails from the extra strain.
• Respiratory failure. In the end stage of chronic interstitial lung disease, respiratory failure occurs when severely low blood oxygen levels along with rising pressures in the pulmonary arteries and the right ventricle cause heart failure