In patients with COPD the normally sterile lower airway is frequently colonised by Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis with exacerbations generally caused by these pathogens or viral infection.
Admission with a first infective exacerbation is COPD is serious event with mortality as high as 10% within a year after first admission and median survival 5-8 years. However, early diagnosis and treatment of exacerbations may prevent hospital admission and delay COPD progression.
Detailed guidelines on the management of acute exacerbations of COPD are available from the Thoracic Society of Australia and New Zealand and Lung Foundation Australia here, with a checklist for managing a COPD exacerbation available here.
A COPD exacerbation is characterised by an acute change in:
- Baseline dyspnoea
- Sputum (beyond normal day-to-day variations)
Once suspected an 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.
Spirometry is useful as COPD is defined by demonstration of airflow limitation, which is not fully reversible, spirometry is essential for its diagnosis but may be performed prior to discharge from hospital when patients are too unwell to complete in the ED.
A screening venous blood gas should be performed on all suspected infective exacerbations of COPD to exclude new acute respiratory failure (demonstrated by a pH< 7.35 with a pCO2 > 50 mmHg). After a venous blood gas with a pCO2 at baseline and a normal pH, an arterial blood gas is never required. Clinicians should remain aware that arterial blood gas sampling is a painful procedure with risk of complications to the patient and staff.
Chest x-ray and electrocardiogram help to identify alternative diagnoses and complications such as pulmonary oedema, pneumothorax, pneumonia, empyema, arrhythmias, myocardial ischaemic and others.
An exacerbation of COPD may involve an increase in airflow limitation, excess sputum production, airway inflammation, infection, hypoxia, hypercarbia, and acidosis. Treatment is directed at each of these problems.
Inhaled beta-agonist (e.g., salbutamol, 400–800mcg by pressurised metered dose inhaler and spacer or 5mg by nebuliser) and Antimuscarinic agent (ipratropium, 80mcg by pressurised metered dose inhaler and spacer or 500mcg by nebuliser) are effective initial treatments. The dose interval is titrated to the response and can range from hourly to six-hourly.
Oral corticosteroids hasten resolution and reduce the likelihood of relapse. Up to two weeks’ therapy with prednisolone (40–50 mg daily) is adequate. Longer courses add no further benefit and have a higher risk of adverse effects.
Antibiotics are given for purulent sputum to cover for typical and atypical organisms an reduce treatment failure
Controlled oxygen therapy:
This is indicated in patients with hypoxia, with the aim of improving oxygen saturation to 88 to 92%. Use nasal prongs at 0.5–2.0 L/minute or a Venturi mask at 24% or 28%. Minimise excessive oxygen administration, which can worsen hypercapnia.
- Admission is indicated for patient with increased dyspnoea, cough, or sputum production, plus one or more of:
- Inadequate response to ambulatory management
- Inability to walk between rooms when previously mobile
- Inability to eat or sleep because of dyspnoea
- Cannot manage at home even with home-care resources
- High risk comorbidity condition — pulmonary (e.g., pneumonia) or non-pulmonary
- Altered mental status suggestive of hypercapnia
- Worsening hypoxaemia or cor pulmonale
- New arrythmia
Non-invasive or invasive ventilation is indicated for:
- Non-invasive or invasive ventilation is indicated for:
- Severe dyspnoea that responds inadequately to initial emergency therapy
- Confusion, lethargy, or evidence of hypoventilation
- Persistent or worsening hypoxaemia despite supplemental oxygen, worsening hypercapnia
- Severe or worsening respiratory acidosis (blood pH < 7.3)
- Non-invasive ventilation by means of a mask is the preferred method ad has proven mortality benefit in exacerbation of COPD.
- Acute COPD NIV pathway in ED flow chart