X2. COPD acute exacerbation plan

X2.1 Confirm exacerbation and categorise severity

Assessment of severity of the exacerbation includes a medi­cal history, examination, spirometry and, in severe cases (FEV₁ < 40% predicted), blood gas measurements, chest x- rays and electrocardiography.

Patients should be provided with and bring a summary of their medical problems and treatment (eg, a personal health record). If available, results of previous stable lung function tests and arterial blood gas measurements are invaluable for comparison.

Spirometry: Unless confused or comatose, even the sickest of patients can perform an FEV₁ manoeuvre. An FEV₁ less than 1.0 L (or < 40% predicted) is usually indicative of a severe exacerbation in patients with moderate COPD. For patients with stable levels below these values (ie, severe COPD), the most important signs of a severe exacerbation will be worsening hypoxaemia, acute respiratory acidosis (carbon dioxide retention), or both.

Arterial blood gases: Arterial blood gas levels should be measured if the FEV₁ is less than 1.0 L or less than 40% predicted, or if percutaneous oxygen saturation is less than 90% in the presence of adequate peripheral perfusion or cor pulmonale. Values obtained while breathing room air are the most useful for assessing ventilation–perfusion inequality. A Pao₂ less than 60 mmHg (8 kPa) indicates respiratory fail­ure, while a Paco₂ greater than 45 mmHg indicates ventila­tory failure. Respiratory acidosis indicates acute respiratory failure warranting consideration for assisted ventilation.

Chest x-ray and electrocardiogram: These help to identify alternative diagnoses and complications, such as pulmonary oedema, pneumothorax, pneumonia, empyema, arrhythmias, myocardial ischaemia and others.

A recent study has identified a simple clinical prediction score, the BAP-65 score, based on age, blood urea nitrogen (equivalent to blood urea>9mM/L), acute mental status change and pulse (>109bpm), which predicts in-hospital mortality. (Tabak et al., 2009) In-hospital mortality increased from 2.3% for patients with one risk factor to 14.1% for those with three risk factors.