Interstitial Lung Disease (ILD) - Diagnosis and Management ...
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Description

Interstitial Lung Disease (ILD) - Diagnosis and Management Summary

Overview: Diverse group of disorders that cause scarring/fibrosis in the lungs, often leading to structural changes in the parenchyma (alveoli, interstitium, alveolar-capillary interface) → loss of lung volume/compliance

Clinical Presentation: Progressive dyspnea, non-productive cough, hypoxemia (esp. w/ exercise), acute and chronic presentations

Physical Exam: “Velcro-like” crackles, wheezing, tachypnea, clubbing, signs of connective tissue disease (e.g. heliotrope eruption, photosensitive rash, Gottron’s papules, mechanic’s hands, joint disease, muscle weakness, skin fibrosis, sicca)

Etiologies: Known and unknown causes broken down by subcategories (as well as some rare etiologies)

Idiopathic: 

 • Idiopathic Pulmonary Fibrosis (IPF),

 • Cryptogenic Organizing Pneumonia (COP)

 • Acute Interstitial Pneumonia (AIP) AKA idiopathic ARDS

 • Systemic Diseases: Sarcoid, Amyloid, ANCA vasculitis

 • Connective Tissue Disease: Scleroderma, Polymyositis, Dermatomyositis, RA, SLE

 • Inhalation Exposures: Hypersensitivity Pneumonitis, Pneumoconiosis

 • Drugs: Amiodarone, Nitrofurantoin, Methotrexate, Nivolumab, Pembrolizumab, Ipilimumab, Radiation

Diagnostic Work-up of ILD:

 o Labs: CBC+diff, CMP, ESR/CRP, CPK/aldolase, C3/C4, auto-antibodies (ANA, anti-RNP, anti-Ro/La, Scl-70; RF/anti-CCP, ANCA, hypersensitivity panel, myositis panel 3, anti-Jo1 (included in myositis panel but comes back faster)

 o Radiology: CXR, HRCT ILD-protocol (see below)

 o PFTs: Restrictive defect (↓TLC, ↓FRC, ↓RV and ↓DLCO = early sign; FEV1/FVC normal to increased)

 o BAL: Not diagnostic for most ILDs (except eosinophilic PNA) but helpful to rule out infection which can have role in acute ILD exacerbations

 o Lung biopsy: Pursue when radiology not definitive; gold standard for diagnosis

Radiographic features -> High Res CT chest is key for diagnosis

 o Usual Interstitial Pneumonia (UIP) is the radiographic corollary of IPF

     - UIP (left): basilar predominant, honeycombing, traction bronchiectasis

o Non-IPF pathologies will have a Non-Specific Interstitial Pneumonia (NSIP) pattern

     - NSIP (right): subpleural sparing, increased reticular markings, ground glass, mosaic attenutation due to air trapping (requires inspiratory/expiratory high-res CT), hypersensitivity pneumonitis will be upper lobe predominant

Treatment:

 o IPF - Chronic therapy: consideration for pirfenidone (antifibrotic), nintedanib (tyrosine kinase inhibitor) (reduces FVC decline but no ↑ survival), aggressive GERD treatment and aspiration precautions may be beneficial, ↑ mortality with azathioprine/prednisone/NAC and NAC monotherapy with minimal side effects but no clear benefit, steroids are not indicated, lung transplant evaluation

 o IPF - Acute exacerbations: steroids and broad spectrum abx recommended

 o NSIP: remove inciting exposures, treat underlying condition, can be steroid-responsive; consider biologic agents such as rituximab or cyclophosphamide in myositis-associated ILD (rheum consult)

 o COP: monitor but if symptomatic/disease progression with respiratory impairment -> prednisone

 o AIP: supportive; usually not steroid-responsive but consider high dose methylpred as in-hospital mortality >50%



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