Key Facts

Acute exacerbations of COPD (AECOPD) are major events in the natural history of the disease, associated with accelerated lung function decline, reduced quality of life, and increased mortality. Prompt treatment and structured follow-up are essential.

Epidemiology

COPD is the 5th leading cause of death in the UK. There are approximately 115,000 emergency hospital admissions for AECOPD annually. In-hospital mortality is approximately 7-10%. The 90-day mortality after an exacerbation is approximately 15%. COPD costs the NHS approximately £1.9 billion annually.

Aetiology

• Infective (most common): Viral (rhinovirus, influenza, RSV) ~50%; bacterial (H. influenzae, S. pneumoniae, M. catarrhalis) ~30%; mixed ~20%
• Non-infective: Air pollution, cold weather, non-adherence, PE, pneumothorax, heart failure
• Frequent exacerbators: ≥2 exacerbations/year — distinct phenotype with worse outcomes

Pathophysiology

Exacerbations involve increased airway inflammation, bronchospasm, and mucus hypersecretion leading to worsened airflow obstruction, dynamic hyperinflation, and ventilation-perfusion mismatch. In severe cases, respiratory muscle fatigue leads to hypercapnic respiratory failure (type 2). Excessive supplemental oxygen suppresses hypoxic respiratory drive, worsening CO2 retention via the Haldane effect and V/Q redistribution.

Clinical Features

• Increased dyspnoea, increased sputum volume and/or purulence, increased cough
• Wheeze, tachypnoea, use of accessory muscles
• Peripheral oedema (cor pulmonale)
• Confusion, drowsiness (hypercapnia — CO2 narcosis)

Severity Assessment

• Mild: Increased breathlessness, can manage at home with increased bronchodilators
• Moderate: Requires steroid ± antibiotic course
• Severe: Hospital admission required — respiratory failure, failure of outpatient treatment

Red Flags

• Altered consciousness (confusion, drowsiness) — hypercapnic respiratory failure
• pH <7.35 with PaCO2 >6 kPa — respiratory acidosis requiring NIV
• SpO2 <88% on controlled O2 — severe exacerbation
• pH <7.25 despite NIV — consider intubation and ICU
• Acute onset pleuritic chest pain — consider PE or pneumothorax

Bedside

• ABG: Essential — pH, PaCO2, PaO2, lactate (guides need for NIV)
• SpO2: Target 88-92% on controlled O2
• Sputum sample: If purulent — MC&S
• ECG: Exclude MI, arrhythmia; may show P pulmonale, right axis deviation

Bloods

• FBC: WCC (infection), Hb (polycythaemia in chronic hypoxia)
• CRP: Infection marker
• U&Es: Renal function, K⁺
• BNP/NT-proBNP: If heart failure co-existing
• Theophylline level: If on maintenance theophylline
• Blood cultures: If fever/septic

Imaging

• CXR: Exclude pneumonia, pneumothorax, effusion, heart failure
• CTPA: If PE suspected (Wells score assessment)

Special Tests

• Sputum culture: Guide antibiotic therapy
• Spirometry: NOT during acute exacerbation — perform when stable to confirm diagnosis and severity

Non-pharmacological

• Controlled oxygen therapy: 24-28% Venturi mask to target SpO2 88-92%; titrate up cautiously; repeat ABG at 30-60 min
• Physiotherapy: Chest physiotherapy for sputum clearance
• Fluid balance: Avoid fluid overload

Pharmacological

• Nebulised bronchodilators: Salbutamol 5mg + ipratropium 500mcg QDS (drive with air if hypercapnic; supplement O2 via nasal prongs)
• Prednisolone 30mg PO for 5 days (REDUCE trial)
• Antibiotics (if increased sputum purulence): Amoxicillin 500mg TDS or doxycycline 200mg day 1 then 100mg OD for 5 days; co-amoxiclav 625mg TDS if severe
• IV aminophylline: 5mg/kg loading then 0.5mg/kg/hr if poor response (NOT if on oral theophylline)

NIV (Non-Invasive Ventilation)

• Indication: Respiratory acidosis pH 7.25-7.35 with PaCO2 >6 kPa despite optimal medical therapy
• Settings: BiPAP — IPAP 12-20 cmH2O, EPAP 4-6 cmH2O; titrate to response
• Repeat ABG: At 1-2 hours — if no improvement, escalate
• NIV reduces mortality by 46% and intubation rates (Cochrane review)

Surgical/Interventional

• Intubation and invasive ventilation: If NIV fails (pH <7.25 despite NIV), patient deteriorating, or not suitable for NIV
• Chest drain: If pneumothorax

Referral Criteria

• pH <7.35 with PaCO2 >6 kPa — NIV required (respiratory ward or HDU)
• pH <7.25 despite NIV or not suitable for NIV — ICU referral
• All admitted patients — pulmonary rehabilitation referral within 4 weeks of discharge
• Recurrent exacerbations — respiratory specialist review

• In-hospital mortality: ~7-10% for admitted exacerbations
• 90-day mortality post-exacerbation: ~15%
• 1-year mortality after severe exacerbation: ~25%
• Readmission: ~30% readmitted within 30 days
• NIV: Reduces in-hospital mortality from ~20% to ~10% in acidotic patients
• Pulmonary rehabilitation post-exacerbation: Reduces readmission by 50% and improves quality of life
• Each exacerbation accelerates FEV1 decline and worsens prognosis

NICE/BTS NIV Criteria for COPD Exacerbation

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