Interstitial Lung Diseases Pulmonary Medicine Department Ain Shams University

At the end of this lecture the student should be able to: 1. Know the definition of interstitial lung diseases. 2. Discuss the etiology and pathogenesis with emphasis on sarcoidosis, idiopathic pulmonary fibrosis, hypersensitivity pneumonitis and asbestosis. 3. Describe the clinical features. 4. Interpret the investigations (including diffusion capacity, and high-resolution chest computed tomography). 5. List the differential diagnosis. 6. Discuss the treatment (including modalities for long -term oxygen therapy). 2

Definition Diffuse parenchymal lung diseases, often collectively referred to as the interstitial lung diseases (ILDs), are a heterogeneous group of disorders that are classified together because of similar clinical, radiological, physiologic, or pathologic manifestations Diffuse parenchymal lung diseases, often collectively referred to as the interstitial lung diseases (ILDs), are a heterogeneous group of disorders that are classified together because of similar clinical, radiological, physiologic, or pathologic manifestations 3

Classification of ILD 4

The most common identifiable causes of ILD are related to occupational and environmental exposures, especially to inorganic (Asbestosis, silicosis) or organic dusts (bird breeding, wood dust). There are also a variety of ILDs of unknown etiology, including sarcoidosis, idiopathic pulmonary fibrosis (IPF), and pulmonary fibrosis associated with connective tissue diseases (eg, systemic lupus erythematosus, rheumatoid arthritis, scleroderma) 5

Infiltration of alveolar airspaces or thickening of interstitial structures. 6

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Clinical Presentation History: Onset: Chronic: e.g. IIPs, sarcoidosis. Acute or subacute: e.g. EAA, drug induced. Sex: e.g. lymphangioleiomyomatosis ♀. Age: Age: younger (sarcoidosis), IPF (late middle age). Occupational history: Occupational history: listing of lifelong employment. 8

History (cont.) Environmental exposure: pets (especially birds), air conditioners, humidifiers & evaporating cooling systems. Smoking history: alter ILD Smoking history: alter ILD Family History: Family History: e.g. IPF, sarcoidosis. Systematic diseases. Systematic diseases. Current/Previous medications. Current/Previous medications. 9

Symptoms: Typically present with progressive exertional dyspnoea and/or persistent nonproductive cough. Typically present with progressive exertional dyspnoea and/or persistent nonproductive cough. Other unusual chest symptoms: Other unusual chest symptoms: Haemoptysis  e.g. alveolar hemorrhage syndromes, pulmonary vascular diseases & chronic mitral valve disease. Haemoptysis  e.g. alveolar hemorrhage syndromes, pulmonary vascular diseases & chronic mitral valve disease. Pleuritic chest pain  e.g. collagen vascular illness. Pleuritic chest pain  e.g. collagen vascular illness. Wheezing  e.g. Churg -Strauss syndrome & EAA. Wheezing  e.g. Churg -Strauss syndrome & EAA. 10

Signs: Dry bibasilar crepitations / Squeaks. Dry bibasilar crepitations / Squeaks. Clubbing (most common in IPF) Clubbing (most common in IPF) Cyanosis. Cyanosis. Signs of right heart failure. Signs of right heart failure. Extra pulmonary findings: may be helpful in narrowing the differential diagnosis of systemic diseases. Extra pulmonary findings: may be helpful in narrowing the differential diagnosis of systemic diseases. Late in advanced disease 11

Investigations Laboratory studies: Complete blood count with differential, ESR. Complete blood count with differential, ESR. Renal & liver function tests. Renal & liver function tests. Serologic studies: should be obtained if clinically indicated by features suggestive of a connective tissue disease (Antinuclear antibodies, rheumatoid factor), environmental exposure (hypersensitivity precipitin panel), or systemic vasculitis (antineutrophil cytoplasmic antibodies, anti-glomerular basement membrane antibody). Serologic studies: should be obtained if clinically indicated by features suggestive of a connective tissue disease (Antinuclear antibodies, rheumatoid factor), environmental exposure (hypersensitivity precipitin panel), or systemic vasculitis (antineutrophil cytoplasmic antibodies, anti-glomerular basement membrane antibody). 12

Radiology: usually abnormal Chest x-ray: normal ~ 10%. Chest x-ray: normal ~ 10%. High resolution CT scan chest High resolution CT scan chest Radiological pattern of disease Radiological pattern of disease Reticulo / Nodular. Reticulo / Nodular. Alveolar shadows Alveolar shadows Pleural involvement Pleural involvement Honeycomb Honeycomb Interlobar septal thickening Interlobar septal thickening Hilar adenopathy Hilar adenopathy Anatomical distribution (upper or lower zone) Anatomical distribution (upper or lower zone) 13

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Patchy abnormalities predominate in the periphery of the lung & lower lobes Reticular and honeycomb changes often associated with ground glass opacification and traction bronchiectasis 15

Traction bronchiectasis Honeycomb Subpleural distribution 16

PULMONARY FUNCTION TESTING: PULMONARY FUNCTION TESTING: Complete lung function testing (spirometry, lung volumes, diffusing capacity) Complete lung function testing (spirometry, lung volumes, diffusing capacity) Measurement of lung function is helpful in assessing the severity of lung involvement in patients with ILD. In addition, the finding of an obstructive versus a restrictive pattern is useful in narrowing the number of possible diagnoses. Smoking history must be considered when interpreting the functional studies. 17

Most of the interstitial disorders have a restrictive defect with reductions in total lung capacity (TLC), functional residual capacity (FRC), and residual volume (RV). Flow rates are decreased (FEV1 and FVC), but the changes are in proportion to the decreased lung volumes; thus, the FEV1/FVC ratio is usually normal or increased. The reductions in lung volumes become more pronounced as lung stiffness worsens with disease progression. 18

Arterial blood gas: Arterial blood gas: The resting arterial blood gases may be normal or may reveal hypoxemia (secondary to mismatching of ventilation to perfusion) and respiratory alkalosis. Carbon dioxide retention is rare and usually a manifestation of end-stage disease. Importantly, a normal resting PaO 2 (or O 2 saturation by oximetry) does not rule out significant hypoxemia during exercise or sleep, which is common in ILD. However, secondary erythrocytosis is rarely observed in uncomplicated ILD. However, secondary erythrocytosis is rarely observed in uncomplicated ILD. 19

Fiberoptic Bronchoscope: Fiberoptic Bronchoscope: Isotope scan Isotope scan Lung biopsy & histopathological examination. Lung biopsy & histopathological examination. 20

The treatment varies according to disease The treatment varies according to disease Corticosteroids are the therapy used for several diagnoses. Corticosteroids are the therapy used for several diagnoses. Immunosuppressive drugs particularly azathioprine and cyclophosphamide, have been the most commonly employed additive drugs with corticosteroids in some patients. Immunosuppressive drugs particularly azathioprine and cyclophosphamide, have been the most commonly employed additive drugs with corticosteroids in some patients. Supplemental oxygen and pulmonary rehabilitation. Supplemental oxygen and pulmonary rehabilitation. For end-stage disease, lung transplantation remains a restricted, but often effective option. For end-stage disease, lung transplantation remains a restricted, but often effective option. Treatment 21

Thank you 22