Decision support only — not a substitute for the COPD-X Plan, eTG, or your respiratory team. The ABG drives the management: it tells you who needs NIV. Controlled oxygen and a decision on ceiling of care both belong in the first hour. Confirm antibiotic choice against local resistance/eTG and verify all doses.
1 The ABG drives escalation
AECOPD, no respiratory failureSpO₂ adequate on air/low-flow
Increased dyspnoea / cough / sputum. Normal pH & PaCO₂.
The bundle: controlled O₂ 88–92%, salbutamol + ipratropium, oral prednisolone, antibiotics if purulent.
Type 1 failurehypoxaemic, PaCO₂ normal
PaO₂ low, PaCO₂ normal/low, pH normal.
Bundle + titrate O₂ to 88–92%. CXR to exclude pneumonia / pneumothorax / effusion.
Type 2, not acidotichypercapnic, pH ≥7.35
PaCO₂ raised but compensated (chronic, or early).
Controlled O₂, nebs on air, repeat ABG 30–60 min. Watch for CO₂ narcosis (drowsiness). NIV if it tips acidotic.
Type 2 + acidosispH <7.35, PaCO₂ ≥45 / 6 kPa
Persistent respiratory acidosis despite ~1h optimal medical therapy.
NIV (BiPAP) — early, in a monitored area. Strongest single intervention: cuts intubation and death.
NIV failing / life-threateningpH falling, ↓GCS, exhaustion
Worsening pH/CO₂ on NIV, declining consciousness, or imminent arrest.
Intubation + ICU vs ceiling of care — decide early, not at 3am in extremis. Involve patient/family + seniors.
AECOPD itself rarely causes severe hypoxaemia — if SpO₂ is very low, look for pneumonia, pneumothorax, PE, or heart failure. Make the ceiling-of-care decision on admission while the patient can still participate, not when they're peri-arrest.
2 The first-hour bundle
Controlled oxygen gets people killed
- TargetSpO₂ 88–92% in known/suspected COPD. Nasal prongs 0.5–2 L/min or Venturi 24–28%.
- WhyHigh-flow O₂ increased mortality in COPD (Austin 2010) — titrate, don't flood.
- NebsDrive on air if hypercapnic; run O₂ separately by prongs to hold 88–92%.
Bronchodilators & steroids
- SABA+SAMASalbutamol 5 mg + ipratropium 500 µg neb (or pMDI+spacer — equivalent). Repeat salbutamol PRN.
- SteroidPrednisolone 40–50 mg PO daily. 5 days is enough (REDUCE); COPD-X allows up to 2 weeks, no taper needed.
- Eos?Emerging: blood eosinophils may select who benefits from steroids (Ramakrishnan 2024) — not yet standard.
Antibiotics — only if indicated
- WhenPurulent sputum plus increased volume and/or dyspnoea (Anthonisen), or needing ventilation.
- WhatAmoxicillin or doxycycline 5 days per local/eTG. Oral preferred over IV.
- Not allNot every exacerbation needs antibiotics — viral and non-infective triggers are common.
3 Workup & what not to miss
Investigations
- ABGEarly — defines respiratory failure type and the NIV decision. Repeat after intervention.
- CXRPneumonia, pneumothorax, effusion, mass, pulmonary oedema.
- ECG + bloodsArrhythmia/ischaemia; FBC, U&E, CRP. Sputum culture if productive, blood cultures if febrile.
The mimics & the missed PE
- PEConsider PE in an exacerbation with no clear infective/obvious trigger — prevalence is meaningful (SLICE).
- MimicsHeart failure, pneumonia, ACS, pneumothorax can all masquerade as "an exacerbation."
- Not helpfulAminophylline/theophylline not routine — no benefit, real toxicity. Mucolytics/chest physio: limited.
4 NIV & escalation
Non-invasive ventilation
- IndicationRespiratory acidosis pH <7.35 + PaCO₂ ≥45 (6 kPa) despite ~1h optimal therapy. Start early.
- StartBiPAP, e.g. IPAP ~12–15 / EPAP ~4–5, titrate to tidal volume, comfort, pH. Monitored area.
- RecheckABG at ~1h — improving pH/CO₂ predicts success. Treat the underlying cause in parallel.
When NIV isn't the answer
- FailsNo improvement / falling pH / intolerance → escalate to intubation if appropriate.
- CeilingFor many, NIV is the ceiling — document it. Decide before the crisis.
- CautionReduced GCS, vomiting, facial trauma, untreated pneumothorax limit NIV — weigh case by case.
5 Before discharge — stop the revolving door
The two big levers
- SmokingCessation — the only intervention that changes the disease trajectory. Offer support + pharmacotherapy every time.
- Pulm rehabRefer — post-exacerbation rehab cuts readmission and mortality. Ideally within weeks.
- InhalersCheck technique; optimise maintenance (LABA/LAMA ± ICS by eosinophils/exacerbation history).
The bundle out the door
- Action planCOPD Action Plan ± rescue pack; teach red flags.
- VaccinateInfluenza, pneumococcal, COVID.
- O₂ + follow-upAssess for home O₂ (don't start on acute hypoxaemia alone); GP review within 7 days; nebs off ~24h pre-discharge.
Sources.
COPD-X Plan — Australian & New Zealand Guidelines for the Management of COPD (Lung Foundation Australia / TSANZ), V2.78 Dec 2025, "Manage exacerbations." GOLD 2025 report. NSW ACI Emergency Care Institute COPD pathway. eTG (antibiotic selection).
Key trials: Austin 2010 BMJ (titrated vs high-flow O₂ — mortality); REDUCE 2013 (5-day vs 14-day steroids — non-inferior); Ramakrishnan 2024 (eosinophil-directed steroids); Plant 2000 / Cochrane (NIV in AECOPD); SLICE (PE in exacerbations).
Caveats: antibiotic choice is resistance-dependent — confirm against local/eTG. Steroid duration wording differs (GOLD/REDUCE 5 days; COPD-X up to 2 weeks) — both acceptable, short course preferred. NIV settings are starting points, not prescriptions. Verify all doses; make the ceiling-of-care decision explicit and early.