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Interstitial Lung Disease – Evidence Reviewed

Interstitial Lung Disease

Interstitial Lung Disease 2018-01-30T16:38:24+08:00

Relevant physical signs

  • General inspection
    • Oxygen cylinder / supplemental oxygen
    • Signs of respiratory distress
    • Plethora (polycythaemia)
    • Symmetrical chest expansion, possibly reduced
    • Rash (dermatomyositis)
    • Cushingoid appearance, bruising, thin skin (steroid use)
    • Scars (VATS / thoracotomy) for lung biopsy
  • Hands & wrists
    • Clubbing
    • Peripheral cyanosis
    • Aetiology: connective tissue disease
      • RA: symmetrical deforming polyarthropathy
      • Systemic sclerosis: sclerodactyly, Raynaud’s, calcinosis
      • Anti-synthetase syndrome: mechanic’s hands +/- Gottron’s papules
      • Psoriasis: scaly plaques on extensor surfaces of hands
      • Amiodarone: irregular pulse, slate grey skin
    • Pulse, asterixis: CO2 retention
  • Face
    • Anaemia (anaemia of chronic disease)
    • Central cyanosis
    • Aetiology:
      • Heliotrope rash (dermatomyositis)
      • Malar rash (systemic lupus erythematosus)
      • Tight facies, telangiectasia (systemic sclerosis)
  • Neck
    • JVP: raised in right heart failure
    • Trachea – usually symmetrical unless fibrosis is unilateral
    • Lymphadenopathy – sarcoidosis, SLE
  • Chest:
    • Scars: mediastinoscopy, VATS, previous chest drains, previous radiotherapy
    • Chest expansion: usually reduced bilaterally
    • Signs of pulmonary hypertension
      • Palpable P2
      • Right ventricular heave
      • Loud P2
      • Displaced apex beat
      • PSM of tricuspid regurgitation
    • Percussion: may be dull at bases
    • Auscultation: the classic finding in idiopathic pulmonary fibrosis is the presence of bilateral, fine, late-inspiratory crepitations at the bases which do not clear on coughing. These crepitations may extend to the mid-zone.
      • There is usually no wheeze, unless there is concomitant airway obstruction
  • Legs
    • Pitting oedema (right heart failure)
    • Aetiology:
      • Livedo reticularis (systemic lupus erythematosus)
      • Erythema nodosum (sarcoidosis)
  • Complete my examination by:
    • Looking at vitals chart (temperature, SpO2)
    • Obtaining a detailed drug history
    • Obtaining a detailed occupational history
    • Examining the skin and musculoskeletal system for signs of rheumatic disease
    • Obtaining a chest radiograph
    • Obtaining an electrocardiogram to look for signs of right ventricular hypertrophy

Differential diagnosis

  • Bronchiectasis (usually coarse crepitations at the beginning of inspiration, productive cough)
  • Lung malignancy (may expect locoregional lymphadenopathy, cachexia, tar stains)
  • Lung abscess

Causes of interstitial lung disease

  • Idiopathic pulmonary fibrosis
  • Connective tissue disease
    • Systemic lupus erythematosus
    • Rheumatoid arthritis
    • Systemic sclerosis
    • Seronegative spondyloarthropathies: ankylosing spondylitis, psoriasis
    • Mixed connective tissue disease
    • Sjogren’s syndrome
    • Dermatomyositis
    • Polymyositis / anti-synthetase syndrome
  • Vasculitis
    • Wegner’s granulomatosis
    • Churg-Strauss syndrome
  • Drugs
    • Anti-arrhythmics: amiodarone, procainamide
    • Antibiotics: nitrofurantoin, isoniazid
    • Cytotoxics: bleomycin, cyclophosphamide
    • Anti-rheumatics: methotrexate, gold, sulphasalazine
  • Occupational lung disease
    • Coal workers’ pneumoconiosis
    • Silicosis
    • Berylliosis
    • Asbestosis
    • Extrinsic allergic alveolitis (hypersensitivity pneumonitis), e.g farmer’s lung, bird fancier’s lung
  • Radiotherapy (e.g. for Hodgkin lymphoma, breast carcinoma)
  • Infection
    • Tuberculosis
    • Aspergillosis

 Causes of apical fibrosis (BREAST)

  • Bronchopulmonary aspergillosis
  • Radiotherapy
  • Extrinsic allergic alveolitis
  • Ankylosing spondylitis / psoriatic arthritis
  • Silicosis / coal worker’s pneumoconiosis
  • Tuberculosis

Causes of lower lobe fibrosis (DAM IRS)

  • Drugs
  • Asbestosis
  • Mixed connective tissue disease
  • Idiopathic pulmonary fibrosis
  • Rheumatoid arthritis
  • Systemic sclerosis

Investigations

  • Confirm diagnosis: high resolution computed tomography scan of the lungs
    • Ground-glass changes suggestive of parenchymal inflammation
    • Reticular abnormalities with honeycombing in the later stages
  • Assess severity of disease
    • Spirometry – restrictive pattern: reduced total lung capacity and residual volume, FEV1/FVC > 0.7 (unless concomitant obstructive airways disease), reduced DLCO
    • Arterial blood gas: type 1 respiratory failure. May require LTOT if pO2 < 55mmHg.
  • Chest radiograph: useful as a baseline, can compare for super-imposed infection
    • Reticulonodular infiltrates
    • Honeycombing in severe cases
    • Pleural plaques in asbestosis
  • Look for an underlying cause
    • Erythrocyte sedimentation rate (elevated in chronic inflammatory conditions
    • If clinically suspected based on history and examination: anti-nuclear antibody, extractable nuclear antigens, anti-neutrophil cytoplasmic antibody, rheumatoid factor, anti-cyclic citrullinated peptide antibody
    • Creatine kinase (dermatomyositis / polymyositis)
    • Serum precipitins (IgG antibodies against various allergens)
  • Look for complications of the disease
    • Pulmonary hypertension: electrocardiogram (peaked p wave, dominant R wave in V1), transthoracic echocardiogram (pulmonary artery systolic pressure > 25mmHg)
    • Polycythaemia: full blood count
    • Pneumonia: chest radiograph, full blood count
    • Respiratory failure: arterial blood gas
    • Pneumothorax: chest radiograph
    • Lung malignancy: chest radiograph

Management

  • Multi-disciplinary approach
  • Patient education
    • If smoking, will need to stop
    • Five-yearly pneumococcal and yearly influenza vaccine
    • Stop any toxic medications
    • Avoidance of allergens / occupational dusts
  • Pulmonary rehabilitation
  • Pharmacological
    • Antibiotic therapy for any acute infections
    • Immunosuppression depending on underlying cause
    • Long-term oxygen therapy if:
      • Resting PaO2 < 55mmHg or SpO2 < 88% RA, or
      • PaO2 < 60mmHg or SpO­2­ < 90% RA with evidence of secondary polycythaemia or cor pulmonale
    • Consider pirfenidone in patients with idiopathic pulmonary fibrosis (anti-fibrotic)
  • Surgery: lung transplantation in advanced disease and selected patients

Presentation

Sir, this patient is clubbed and has bilateral, fine, late-inspiratory crepitations on auscultation. The character of the crepitations do not change with coughing. This is in keeping with interstitial lung disease, but other possibilities include bronchiectasis and an underlying mitotic lesion. He is not cyanotic and not in respiratory distress. There is no asterixis or bounding pulse to suggest carbon dioxide retention. There is no palpable lymphadenopathy, and the trachea is central.

With regards to aetiology, there are no obvious stigmata of connective tissue disease. With regards to complications of the disease, there is no plethora to suggest polycythaemia. Clinically, there is no sign of pulmonary hypertension or cor pulmonale – there is no right ventricular heave, the P2 is not loud, there is no evidence of tricuspid regurgitation, the jugular venous pulse is not raised and there is no pedal oedema.

In summary, this patient bilateral pulmonary fibrosis. Possible causes include idiopathic pulmonary fibrosis, connective tissue disease such as ankylosing spondylitis, rheumatoid arthritis or systemic sclerosis, drugs such as amiodarone, methotrexate, bleomycin and nitrofurantoin, occupational lung disease such as silicosis, asbestosis or coal workers’ pneumoconiosis and radiotherapy.

OR: with regards to aetiology, the patient has a symmetrical deforming polyarthropathy, mainly affecting the hands. This suggests a diagnosis of rheumatoid arthritis complicated by pulmonary fibrosis.

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This Sliding Bar can be switched on or off in theme options, and can take any widget you throw at it or even fill it with your custom HTML Code. Its perfect for grabbing the attention of your viewers. Choose between 1, 2, 3 or 4 columns, set the background color, widget divider color, activate transparency, a top border or fully disable it on desktop and mobile.