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Medicine Notes Respiratory Notes

Interstitial Lung Disease Notes

Updated Interstitial Lung Disease Notes

Respiratory Notes

Respiratory

Approximately 35 pages

Complete set of notes covering the respiratory system. Includes pathophysiology, aetiology, presenting symptoms, management and relevant pharmacology. Concise bullet points, colour coded by topic. Includes tables and summary charts. All you need to pass respiratory module at medical school....

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The following is a more accessible plain text extract of the PDF sample above, taken from our Respiratory Notes. Due to the challenges of extracting text from PDFs, it will have odd formatting:

Interstitial Lung Disease

= Group of conditions causing diffuse parenchymal lung disease characterized by chronic inflammation +/- progressive interstitial fibrosis

Common clinical features

  • Extertional dyspnea

  • Non-productive cough

  • Abnormal breath sounds

  • Abnormal CXR/HRCT

  • Restrictive pattern on spirometry

    • Reduced FEV and reduced FVC (therefore ratio >80% = normal ratio)

Classification

  • Those with known aetiology e.g

    • Occupational/environmental e.g asbestosis, silicosis

    • Drugs e.g amiodarone, nitrofurantoin, sulfasalazine

    • Hypersensitivity e.g extrinsic allergic alveolitis

    • Infections e.g TB, fungi, viral

  • Those with associated systemic disorders

    • Sarcoidosis

    • RA

    • SLE, systemic sclerosis, sjogren’s syndrome

    • UC, autoimmune, thyroid disease

  • Idiopathic

    • Idiopathic pulmonary fibrosis/cryptogenic fibrosing alveolitis

    • Cryptogenic organizing pneumonia

    • Lymphocytic interstitial pneumonia

Extrinsic Allergic Alveolitis

A condition caused by hypersensitivity to inhaled organic dusts (e.g fungal spores, avian proteins) leading to an inflammatory reaction in distal airspaces

Aetiology

  • Inhalation of various antigens may result in a pulmonary inflammatory response

  • E.g

    • Farmers Lung = mouldy hay (thermophilic actinomycetes)

    • Pigeon Fanciers Lung (pigeon, budgie, poultry (bloom))

    • Woodworker’s Lung (Wood, dust)

Pathophysiology

Inhalation of allergens

Hypersensitivity reaction

Acute phase Chronic exposure

Alveoli infiltrated with acute inflamm. Cells Granuloma formation

Obliterative bronchiolitis

Fibrosis

Acute allergic alveolitis

  • 4-8 hrs after exposure to high doses of antigen

  • Systemic features = fever, malaise, headache

  • Cough, breathlessness

  • Inspiratory crackles, wheeze + cyanosis

Chronic allergic alveolitis

  • Prolonged low level antigen exposure causes features

  • Progressive exertional breathlessness

  • May be hx of acute episodes

  • Weight loss

  • Fine end insp. Crackles, cyanosis

  • +/- Type 1 respiratory failure cor-pulmonale

Investigation Acute Chronic

Bloods

  • WCC, ESR

Imaging

  • CT scan

  • CXR

ABG

Lung Function Tests

Raised

Multiple nodules

Low lung volume, reticulo-nodular shadows

Type 1 resp. failure

Restrictive defect

May be normal

Fibrosis

Fibrosis

Type 1 resp. failure

Restrictive defect

Management

  • Acute attack

    • Remove allergen

    • Give O2 (35-60%)

    • Oral prednisolone (40mg/24 hr PO) followed by reduced doses

    • Lung biopsy if diagnosis uncertain

  • Chronic attack

    • Avoid allergen exposure / wear facemask

    • Long term steroids often achieve CXR + physiological improvement

    • Compensation may be payable

Fibrosing Alveolitis

A condition involving inflammation and fibrosis of distal airspaces

Aetiology

  • Unknown cause

  • Probable inhaled or environmental agent

Pathophysiology

  • Alveolar walls become progressively thickened as a result of inflammatory cell infiltrate with proliferation of fibroblasts

  • Lung volume is decreased+ diffusion impaired (resp. failure develops)

  • Increased risk of lung cancer (10% of pts)

Clinical features

Symptoms Signs

Dry cough

Exertional dyspnea

Malaise

Weight loss

Arthralgia

Cyanosis

Finger clubbing

Fine end inspiratory crackles

Investigations

  • Bloods

    • ABG (decreased pO2, raised pCO2)

    • Raised CRP

    • Raised Igs

    • ANA, RF

  • Imaging

    • CXR (decreased lung volume, bilaretal LL reticulo-nodular shadows, honeycomb lung)

    • MRI/CT

  • Lung Function Tests

    • Restrictive pattern

  • Broncheoalveolar lavage

    • May indicate activity of alveolitis

      • Raised lymphocytes = good response

      • Raised neutrophils/eosinophils = poor response

  • Lung biopsy if necessary

Management

  • May have poor response to treatment

  • Can try oral prednisolone with tapering dose

    • Monitor response with CXR, lung func. Tests + symptoms

- Lung transplantation should be...

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