Asthma exacerbation: workup and management
Acute asthma: assess severity with work of breathing, ability to speak, oxygen saturation and peak flow. Treat with oxygen to 93–95%, repeated inhaled short-acting bronchodilators with ipratropium, early systemic corticosteroids and IV magnesium for severe attacks. Rising or normal CO₂ in a distressed patient is a danger sign.
Working diagnosis
Adult · US guidelines
Draft · awaiting physician review
01Orient
What's new in the evidence
- GINA 2026: target SpO₂ 92–95%; no routine chest X-ray or antibiotics
- Admit if SpO₂ <92%, reliever needed more often than every 1–2 hours, or dyspnea persists 4–6 hours after steroids
- Discharge on ICS-containing therapy (ICS-formoterol as reliever where appropriate); SABA-only treatment is not recommended
- In anaphylaxis presenting as wheeze, give epinephrine first (IM or intranasal)
Differential diagnoses
- Asthma exacerbation
- Pneumothorax (can't miss)
- Anaphylaxis (can't miss)
- Pneumonia, COPD exacerbation
- Heart failure (cardiac asthma)
- Vocal cord dysfunction, foreign body
- Pulmonary embolism
02Assess
Risk scores and decision tools
- Peak flow (% predicted or personal best)
- Ability to speak, accessory muscle use, SpO₂
- PaCO₂ normal or rising = impending respiratory failure
Key history questions
- Triggers: viral infection, allergens, smoke, NSAIDs or beta-blockers
- Reliever use in recent days; controller adherence
- Prior ICU admission or intubation (high risk)
- Oral steroid courses in the past year
- Symptom duration and trajectory
Examination findings
- Ability to speak in sentences, accessory muscle use, respiratory rate
- SpO₂, heart rate, pulsus paradoxus
- Silent chest, exhaustion, confusion (life-threatening)
- Peak expiratory flow (% predicted or personal best)
03Investigate
Initial investigations
- Peak flow before and after treatment
- SpO₂; blood gas if severe or not improving
- Chest X-ray if pneumothorax, pneumonia or atypical features suspected
Advanced investigations
- CBC (eosinophils), viral testing in season
- Spirometry when stable
04Treat
Immediate management
- Oxygen to SpO₂ 93–95%
- Albuterol by MDI-spacer or nebulizer, repeated or continuous in the first hour
- Ipratropium with albuterol in moderate to severe exacerbations
- Prednisone 40–50 mg (or IV methylprednisolone if unable to swallow) within the first hour
First-line treatment
- Magnesium sulfate 2 g IV over 20 minutes for severe exacerbations or poor response
- Continue oral corticosteroid for 5–7 days; no taper needed
- Start or step up inhaled corticosteroid-containing therapy before discharge
Second-line treatment
- Impending respiratory failure: ICU, consider noninvasive ventilation in selected patients, early intubation by an expert
- Avoid sedation outside the ICU
Specialist referrals
- ICU for life-threatening features or rising CO₂
- Pulmonology or asthma clinic for frequent exacerbations
05Disposition
Admission criteria
- Peak flow <50% after initial treatment, persistent hypoxia or distress
- Prior near-fatal asthma, poor social support
- Life-threatening features at any time
Safe discharge criteria
- Peak flow ≥60–70% predicted and symptoms controlled
- Inhaler technique checked; controller started; written action plan
- Follow-up within 1 week
Follow-up timing
- Primary care or asthma clinic within 1 week
Patient instructions
- Finish the steroid course; use your controller every day
- Return if reliever is needed more than every 4 hours
Monitoring
- SpO₂, peak flow, respiratory rate; repeat blood gas if severe
Clinical pearls and pitfalls
- A normal or rising PaCO₂ in a tachypneic asthmatic means fatigue and impending failure
- Antibiotics are not routinely indicated
- Never discharge on reliever alone; ICS-containing therapy reduces future attacks
RefGuidelines and landmark evidence
For education only. Typical adult starting points; confirm doses against renal function, allergies, interactions and your institution's protocols. Not a substitute for clinical judgment or senior review.