Chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease

 

Characteristics

  1. General term encompassing a spectrum of conditions including chronic bronchitis and emphysema.
  2. Characterised by chronic resistance to expiratory airflow from infection, mucosal oedema, bronchospasm and bronchoconstriction, due to reduced lung elasticity.
  3. Causative factors include smoking, chronic asthma, alpha-1 antitrypsin deficiency and chronic infection.

Clinical features

  1. Exacerbations commonly precipitated by infection.
  2. Cough, wheeze and exertional dyspnoea.
  3. Tachypnoea, wheeze, lip pursing (a form of PEEP), use of accessory muscles.
  4. Cyanosis, plethora and signs of right heart failure suggest severe disease and cor pulmonale.
  5. Signs of hypercarbia include coarse tremor, bounding pulse, peripheral vasodilatation, drowsiness, confusion or an obtunded patient.

Radiological features

  1. CXR – only moderately sensitive (40–60%), but highly specific in appearance. Is an easily accessible method of assessing the extent and degree of structural parenchymal damage.
  2. Assessment for complications such as pneumonia, lobar collapse/ atelectasis, pneumothorax or mimics of COPD.
  3. CXR features include hyper-expanded lungs with associated flattening of both hemi-diaphragms, ‘barrel-shaped chest’, lung bullae, coarse irregular lung markings (thickened dilated bronchi) and enlargement of the central pulmonary arteries in keeping with pulmonary arterial hypertension.
  4. REMEMBER to look for lung malignancy/nodules; a common association.
  5. CT – quantifies the extent, type and location of emphysema and bronchial wall thickening. It may also identify occult malignancy.

Differential diagnosis

  1. Lymphangioleiomyomatosis (LAM) and Langerhan’s cell histiocytosis (LCH) can have a similar CXR and CT appearance. The clinical history and imaging together are diagnostic.
  2. Asthma _ superimposed infection.
  3. Extrinsic allergic alveolitis.
  4. Viral infections.

Management

  1. Supplemental oxygen tailored to keep pO2 >7.5 kPa. Beware high concentrations of supplemental pO2, as patients fail to expel the CO2 and develop high pCO2 levels.
  2. Nebulised bronchodilators (oxygen or air driven where appropriate). Adding nebulised ipratropium bromide may help.
  3. Consider an aminophylline or salbutamol infusion.
  4. Corticosteroids unless contraindicated.
  5. Appropriate antibiotics should be given if infection suspected.
  6. Ventilation or BiPAP can be considered.
  7. Long-term management may include
  • Long-term home oxygen.
  • Lung reduction surgery.

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