Interstitial Lung Disease

Physical Examination

General examination:

• Tachypnoea (advanced disease)

• Central cyanosis

Chest inspection:

• Flattened chest (affected side)

Palpation:

• Reduced chest expansion

• Increased tactile vocal fremitus and resonance (difficult to appreciate)

Percussion:

• Dullness to percussion (affected zones)

Auscultation:

• Fine end-inspiratory crepitations (affected zones)

• Unaffected by coughing

Other signs:

• Evidence of pulmonary hypertension

• Signs of treatment, such as steroid purpura and oxygen supplementation

If associated with underlying causes:

• Slate grey appearance from amiodarone

• Peripheral symmetrical deforming polyarthropathy (swan neck deformity, Z thumb, ulnar deviation at wrist, may have nodules) from rheumatoid arthritis

• Cutaneous signs of systemic sclerosis, lupus, etc. from connective tissue disease

• Question mark posture, protuberant abdomen from ankylosing spondylitis

• May have radiation tattoo on chest wall, lymphadenopathy from radiation

• Cutaneous signs of sarcoidosis

Investigations

Laboratory investigations:

• Full blood count, erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP): to assess for evidence of inflammation or infection

• Renal and liver function tests: to assess for organ dysfunction which may impact treatment options or require dose adjustments

• Serum autoantibodies: to screen for autoimmune diseases that can be associated with interstitial lung disease (e.g. anti-nuclear antibody, anti-SSA/SSB, anti-Jo-1, anti-Scl-70)

• Serum immunoglobulins: to assess for hypergammaglobulinemia which may suggest sarcoidosis or connective tissue disease

Imaging investigations:

• Chest X-ray: to evaluate for evidence of interstitial lung disease, assess the extent and distribution of disease, and exclude other lung pathologies

• High-resolution computed tomography (HRCT) of the chest: to confirm the presence of interstitial lung disease, assess the pattern and extent of disease, and guide further management

Invasive investigations:

• Bronchoalveolar lavage (BAL): to obtain fluid and cells from the lungs for microbiological and cytological analysis, and exclude infection

• Transbronchial lung biopsy (TBLB): to obtain tissue samples for histological analysis and confirm the diagnosis of interstitial lung disease

• Video-assisted thoracoscopic surgery (VATS) lung biopsy: for cases where TBLB is inconclusive or not possible, to obtain larger tissue samples for diagnosis

Other investigations:

• Pulmonary function tests (PFTs): Restrictive pattern

• Exercise testing: to assess exercise tolerance and determine the need for oxygen therapy

• Cardiac evaluation: to assess for evidence of pulmonary hypertension or cor pulmonale which may require specific treatment

Management

General management:

• Education and advice on smoking cessation

• Pulmonary rehabilitation

• Annual influenza and pneumococcal vaccination

• Airway clearance techniques (e.g., chest physiotherapy, positive expiratory pressure devices)

• Regular follow-up with a respiratory specialist or multidisciplinary team

• Psychological support for patients with significant symptoms or impact on quality of life

Medical management:

• Antibiotics for exacerbations

• Mucolytic agents (e.g., carbocisteine, dornase alfa) to help clear mucus

• Bronchodilators (e.g., salbutamol) to help with airflow obstruction

• Inhaled corticosteroids to reduce inflammation

• Oxygen therapy for hypoxemia

Surgical management:

• Surgery may be considered for localized disease, particularly if the bronchiectasis is causing significant symptoms or hemoptysis

• Lobectomy, segmentectomy, or pneumonectomy may be performed depending on the extent of the disease

Causes of Interstitial Lung Disease

• Idiopathic Interstitial Pneumonias (IIPs)

• Connective Tissue Disease-associated ILD (CTD-ILD): Rheumatoid arthritis (RA), Systemic sclerosis (SSc), Systemic lupus erythematosus (SLE)

• Hypersensitivity Pneumonitis (HP): Extrinsic allergic alveolitis

• Occupational and Environmental ILD: Asbestosis, Silicosis

• Drug-induced ILD: Amiodarone, Bleomycin, Methotrexate, Nitrofurantoin, Sulfasalazine

• Sarcoidosis

• Vasculitis : Granulomatosis with polyangiitis)

• Miscellaneous causes: Radiation pneumonitis