Lucan · Conditions

COPD exacerbation

Australian guidance: COPD-X Handbook — Exacerbations + eTG Respiratory

1. Definition and epidemiology

A COPD exacerbation is an acute worsening of respiratory symptoms, specifically dyspnoea, cough, and sputum production, that exceeds the normal day-to-day variation a patient experiences and warrants a change in management. In Australia, COPD is under-recognised and under-treated, representing a major public health burden with tobacco smoking responsible for approximately 15 to 20% of clinically significant disease among lifetime smokers. Previous exacerbations are the strongest predictor of future exacerbations and accelerate the decline in lung function over time.

2. Pathophysiology

Robbins Ch 15 describes the foundational pathophysiology. In stable COPD, persistent airflow limitation results from two concurrent processes: small airways disease characterised by goblet cell hyperplasia, mucus plugging, and peribronchiolar fibrosis; and emphysematous destruction of alveolar walls driven by an imbalance between neutrophil-derived proteases (elastase, MMP-9) and antiprotease defences (alpha-1-antitrypsin). This causes air trapping, dynamic hyperinflation, and a reduced surface area for gas exchange.

During an exacerbation, an infectious or environmental trigger (most commonly viral respiratory pathogens such as rhinovirus, or bacteria such as Haemophilus influenzae and Streptococcus pneumoniae) amplifies the existing airway inflammatory response. Increased neutrophilic infiltration, mucosal oedema, and bronchospasm narrow already-compromised airways, worsening ventilation-perfusion mismatch and precipitating hypoxaemia. In severe exacerbations, alveolar hypoventilation causes CO2 retention, respiratory acidosis (pH less than 7.35, PaCO2 greater than 45 mmHg), and type 2 respiratory failure. The resultant hypoxic pulmonary vasoconstriction can acutely worsen right heart strain, particularly in patients with pre-existing cor pulmonale.

3. Clinical presentation and diagnostic criteria

Diagnosis is clinical, based on acute changes in the patient's baseline dyspnoea, cough, or sputum that exceed normal day-to-day variation and are acute in onset. History should document the time course, sputum colour or volume change, fever, and any previous exacerbation frequency within the past 12 months.

On examination, signs of severity include tachypnoea, accessory muscle use, tracheal tug, prolonged expiration, wheeze, and cyanosis. Confusion, drowsiness, or restlessness suggest impending respiratory failure and mandate urgent escalation. Key features pointing to an infective trigger are fever, increased sputum volume, and a change in sputum colour to dark yellow, green, or brown. Critical differential diagnoses that must be excluded are pneumonia, pulmonary embolus, pneumothorax, acute heart failure, ischaemic heart disease, arrhythmia, and anaemia.

4. Investigations and AU-specific cutoffs

Assessment includes pulse oximetry, full blood count, C-reactive protein, sputum culture (not routine, only for lack of response or repeated bacterial infections within months), respiratory viral PCR, and chest X-ray as clinically indicated. A chest X-ray is not routinely required for community-managed exacerbations in most patients.

Arterial blood gas analysis is required if SpO2 falls below 90% or if respiratory failure is suspected; the AU-specific threshold for long-term oxygen eligibility is PaO2 persistently less than or equal to 55 mmHg (SpO2 less than or equal to 88%), or PaO2 less than or equal to 59 mmHg with evidence of polycythaemia, pulmonary hypertension, or right heart failure. Hypercapnic respiratory failure is defined by PaCO2 greater than 45 mmHg with pH less than 7.35. Spirometry should not be performed during an acute exacerbation.

Criteria for hospital transfer include marked worsening of symptoms, SpO2 less than 92% if not on home oxygen, new or worsening peripheral oedema, altered mental state, high fever, chest pain, worsening of comorbidities such as heart failure or diabetes, and inability to safely manage at home.

5. Management

Management follows a three-tier approach, aligned with the COPD-X Handbook algorithm and eTG Respiratory guidance.

Community management (patient improving): Increase short-acting beta2 agonist (SABA) use, for example salbutamol 400 to 800 micrograms (4 to 8 puffs) via pressurised metered-dose inhaler (pMDI) with spacer every 3 to 4 hours, titrated to response. Review inhaler technique and reinforce the COPD Action Plan.

Community management (patient worsening despite SABA): Add oral prednisolone 30 to 50 mg daily for 5 days, then stop; systemic corticosteroids reduce severity and shorten recovery. If clinical features of infection are present (fever, increased sputum volume, or colour change), add oral antibiotics for 5 days, first-line amoxicillin or doxycycline. Intravenous antibiotics are generally not required in the community setting. If not responding at 5 days, review with GP or respiratory specialist and re-examine the COPD Action Plan.

Hospital management: Controlled oxygen is delivered via nasal cannula at 0.5 to 2.0 L/min, targeting SpO2 88 to 92%; over-oxygenation must be avoided as it can precipitate acute respiratory failure and death. Non-invasive ventilation (NIV) should be considered in acute hypercapnic respiratory failure (PaCO2 greater than 45 mmHg, pH less than 7.35), as it reduces mortality, length of stay, and the need for endotracheal intubation. Nebulised bronchodilators, systemic corticosteroids, and antibiotics as above are continued in the inpatient setting.

6. Pharmacology and AU PBS notes

Bronchodilators (first-line): Salbutamol (Ventolin, Asmol) 100 micrograms per puff, 4 to 8 puffs via pMDI with spacer every 3 to 4 hours as required; available on PBS for COPD. For maintenance, LAMA monotherapy is favoured over LABA monotherapy for exacerbation prevention, with tiotropium (Spiriva, Braltus) 18 micrograms via DPI once daily as the most used option; PBS streamlined item for COPD. Indacaterol (Onbrez) 150 micrograms via DPI daily is the only LABA on PBS as monotherapy for COPD.

Corticosteroids (second-line acute): Oral prednisolone 30 to 50 mg daily for 5 days; not PBS-subsidised for COPD exacerbations by a streamlined code, but accessible via standard authority. Inhaled corticosteroid (ICS) alone should not be used in place of systemic steroids in an acute setting.

Antibiotics: Amoxicillin 500 mg three times daily for 5 days (first-line if no penicillin allergy), or doxycycline 100 mg twice daily for 5 days. Antibiotic prescribing should be guided by evidence of infection. Sputum culture is reserved for non-responders or those with repeated infections within months.

Triple inhaler therapy (maintenance, post-exacerbation optimisation): Recommended when a patient has had a severe exacerbation requiring hospitalisation or at least two moderate exacerbations in 12 months despite LABA plus LAMA dual therapy, in combination with ongoing symptoms. Options include single-inhaler fluticasone furoate plus umeclidinium plus vilanterol (Trelegy, PBS listed) or budesonide plus glycopyrronium plus formoterol (Breztri, PBS listed). ICS use carries an increased risk of pneumonia in COPD; the benefit-risk balance must be individualised.

Long-term macrolide therapy: Consider in moderate to severe COPD with frequent exacerbations after optimising all other pharmacological and non-pharmacological therapy; not available on PBS for long-term use and requires respiratory specialist referral.

7. Complications and monitoring

Acute complications include type 1 hypoxaemic respiratory failure, type 2 hypercapnic respiratory failure with respiratory acidosis, acute cor pulmonale with right ventricular decompensation, secondary pneumonia, and in-hospital arrhythmia from hypoxia or electrolyte disturbance. Hospitalisation for an exacerbation independently increases subsequent mortality risk and should trigger advance care planning discussions.

Post-exacerbation monitoring: pulmonary rehabilitation should commence as soon as acute instability resolves, and within 2 to 4 weeks of hospital discharge, as it reduces subsequent hospital admissions and short-term mortality. Review inhaler technique and update the written COPD Action Plan at every post-exacerbation consultation. Patients who have had two or more exacerbations requiring rescue medication within 12 months should be reviewed earlier than scheduled. Spirometry should be repeated once the patient is stable, preferably at least 4 weeks after the exacerbation. SpO2 at rest and arterial blood gas should be reassessed before considering eligibility for long-term domiciliary oxygen. Vaccination status should be confirmed at the post-exacerbation review, with annual influenza, pneumococcal, and COVID-19 immunisations offered to all patients with COPD.

Written for Australian practice and grounded in the guidance named above. Study material only — not medical advice. Always check against current guidelines.