Life-threatening asthma: silent chest, exhaustion, cyanosis, altered GCS, or a normal-to-high PaCO2. Give salbutamol plus ipratropium early, call for senior help, and do not withhold oxygen in severe hypoxia.
Oxygen targets
- Asthma: SpO2 94 to 98%
- COPD at risk of hypercapnia: 88 to 92%, check ABG
- A normal or high PaCO2 during an asthma attack is ominous
COPD exacerbation
- Increase bronchodilator via spacer or nebuliser
- Prednisolone 30 mg for 5 days
- Antibiotics if purulent sputum plus increased dyspnoea
- NIV if respiratory acidosis persists (pH 7.25 to 7.35 with hypercapnia) despite treatment
Moderate asthma
- PEF 50 to 75% best
- Speaking in sentences
- SpO2 92% or more
Acute severe asthma
- PEF 33 to 50%
- Cannot complete sentences
- RR 25 or more, HR 110 or more
Life-threatening
- PEF under 33% or SpO2 under 92%
- Silent chest, cyanosis, exhaustion
- Normal or high PaCO2, arrhythmia
Acute management
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1. Oxygen
Asthma: SpO2 94 to 98%. COPD at risk of hypercapnia: 88 to 92% with an ABG if uncertain.
Asthma: SpO2 94 to 98%. COPD at risk of hypercapnia: 88 to 92% with an ABG if uncertain.
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2. Nebulised therapy
Salbutamol 5 mg plus ipratropium 500 micrograms, back-to-back if severe. Continuous salbutamol only in critical care.
Salbutamol 5 mg plus ipratropium 500 micrograms, back-to-back if severe. Continuous salbutamol only in critical care.
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3. Steroids and magnesium
Prednisolone 40 to 50 mg (asthma) or 30 mg (COPD), or IV hydrocortisone if not oral. IV magnesium 1.2 to 2 g for acute severe or life-threatening asthma not responding.
Prednisolone 40 to 50 mg (asthma) or 30 mg (COPD), or IV hydrocortisone if not oral. IV magnesium 1.2 to 2 g for acute severe or life-threatening asthma not responding.
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4. Escalate
Senior and critical care if tiring, rising CO2, or refractory bronchospasm. NIV for COPD with respiratory acidosis; consider intubation for life-threatening asthma.
Senior and critical care if tiring, rising CO2, or refractory bronchospasm. NIV for COPD with respiratory acidosis; consider intubation for life-threatening asthma.
Discharge (asthma)
- PEF over 75% best and stable on an oral steroid course
- Written action plan and checked inhaler or spacer technique
- GP follow-up within 2 working days
Pitfalls
- Under-treating with a single salbutamol dose
- Uncontrolled high-flow oxygen causing hypercapnia in COPD
- Missing pneumothorax in the breathless patient
- Reassurance from a 'normalising' PaCO2 in asthma
MedPrep - www.medprep.uk - Educational revision aid only. Not clinical guidance. Doses are adult examples; check the BNF, current guidelines and local policy, and seek senior advice. Nov 2026