ILD

• Interstitial lung disease is an umbrella term for a bread spectrum of conditions affecting the lung interstitium. Inflammation leads to fibrosis and eventually the formation of non-functional scar tissue.
• The key presenting features are:

  • progressive shortness of breath on exertion
  • Dry cough
  • Fatigue
  • Connective tissue disease symptoms - arthralgia, difficulty swallowing and dry eyes
• Patients with idiopathic pulmonary fibrosis have typical findings on examination:

  • Bibasal fine end-inspiratory crackles - sounds like velcro due to small airways suddenly opening after being held together
  • Finger clubbing
• General signs on examination:

  • Skin changes - Raynaud's in systemic sclerosis and erythema nodosum in sarcoidosis
  • Arthritic changes
  • Dullness to percussion due to pleural effusion - sarcoidosis and some connective tissue diseases
• ILD risk factors:

  • Increased age
  • Smoking
  • Sex - more common in men
  • Family history
  • Inflammatory conditions such as rheumatoid arthritis
• Diagnosis of interstitial lung disease involves:

  • Clinical features
  • HRCT or CXR - showing a typical ground glass appearance
  • Spirometry
• Spirometry may be normal or show a restrictive pattern:

  • FEV1 and FVC are equally reduced
  • FEV1:FVC ratio greater than 70%
• If there is doubt over the ILD diagnosis, bronchoalveolar lavage or a biopsy can be performed
• Idiopathic pulmonary fibrosis is a progressive form of ILD. There is an insidious onset of SOB. Prognosis after diagnosis is 2-5 years
• Antifibrotics can be given to slow the progression of IPF:

  • Pirfenidone
  • Nintedanib
• Secondary pulmonary fibrosis can be caused by medications such as methotrexate, and inflammatory conditions such as rheumatoid arthritis and sarcoidosis

  Corticosteroids are given as treatment
• Hypersensitivity pneumonitis occurs when there is a type III and IV hypersensitivity reaction to an environmental allergen. Removal of allergen and corticosteroids are treatment.
• Asbestosis is a type of ILD that occurs after asbestos exposure. Asbestos is fibrogenic and oncogenic.
• General management of ILD:

  • Management is mostly supportive
  • Remove or treat underlying cause
  • Long term oxygen therapy
  • Physiotherapy and pulmonary rehab
  • Pneumococcal and flu vaccine
  • Advanced care planning
  • Lung transplant - often too risky
• The most common type of ILD is idiopathic pulmonary fibrosis
• Primary ILD:

  • idiopathic pulmonary fibrosis
  • Acute interstitial pneumonia
  • Desquamative interstitial pneumonia (associated with smoking)
• Secondary causes of ILD:

  • Connective tissue and autoimmune disease - sarcoidosis, RA, SLE
  • Infective - mycoplasma and pneumocystis pneumonia
  • Environmental - asbestosis and silicosis
  • Drugs - methotrexate, amiodarone, bleomycin
• CXR typically shows reticular (fine) opacities

  The location of fibrosis may suggest particular causes
• HRCT findings:

  • Honeycombing (clusters of cystic airspaces)
  • Traction bronchiectasis
  • Reticular opacities (thickening of the lung interstitium)
• Upper zone fibrosis:

  • Coal-worker pneumoconiosis
  • Ankylosing spondylitis
  • Radiation
  • Tuberculosis
  • Sarcoidosis and silicosis
• Lower zone fibrosis:

  • Rheumatoid arthritis
  • Asbestosis
  • SLE
  • Scleroderma
  • Sjogren's syndrome
  • Idiopathic pulmonary fibrosis
  • Drugs
• Medical management varies for each type of ILD:

  • Idiopathic - antifibrotics e.g. pirfenidone and nintedanib
  • Sarcoidosis - corticosteroids
  • Connective tissue disease - corticosteroids and steroid-sparing agents e.g. azathioprine
  • Extrinsic allergic alveolitis - corticosteroids