A 42-year-old man with moderate persistent asthma controlled on low-dose ICS/LABA presents with an acute exacerbation. He reports increased dyspnea, wheezing, and inability to speak in full sentences. Peak expiratory flow (PEF) is 55% of personal best. Oxygen saturation is 92% on room air. What is the most appropriate immediate next step in management?

Explanation

## Acute Asthma Exacerbation: Assessment and Management ### Severity Classification | Feature | Mild–Moderate | Severe | Life-Threatening | | --- | --- | --- | --- | | Dyspnea | Walks easily | Walks with difficulty | At rest, unable to speak | | Speech | Full sentences | Phrases | Words only | | PEF | 50–80% | 30–50% | <30% | | SpO₂ | >95% | 90–95% | <90% | | Accessory muscle use | Absent/mild | Moderate | Severe | | Pulsus paradoxus | Absent | <10 mmHg | >25 mmHg | **Key Point:** This patient has a **severe exacerbation** (PEF 55%, SpO₂ 92%, unable to speak in full sentences). Severe exacerbations require urgent treatment in an acute care setting. ### Immediate Management Algorithm ```mermaid flowchart TD A[Acute asthma exacerbation]:::outcome --> B{Severity assessment}:::decision B -->|Mild-Moderate| C[Outpatient management]:::action B -->|Severe| D[Urgent hospital/ED]:::urgent C --> C1[SABA 4-6 hourly nebulized] C --> C2[Systemic corticosteroids 5-7 days] C --> C3[Review 24-48 hours] D --> D1[Oxygen: SpO₂ ≥94%]:::action D --> D2[SABA + ipratropium nebulized]:::action D --> D3[IV/oral corticosteroids]:::action D --> D4[Consider IV magnesium if no response]:::action D --> D5[CXR, ABG if severe]:::action D1 --> E{Response in 1-2 hours?}:::decision E -->|Good| F[Discharge with oral steroids]:::action E -->|Poor| G[Admit for continuous monitoring]:::urgent ``` ### Treatment Components for Severe Exacerbation **High-Yield:** The three pillars of acute asthma management are: 1. **Oxygen therapy** - Target SpO₂ ≥94% (≥90% in pregnancy) - Continuous pulse oximetry monitoring 2. **Bronchodilators** - SABA (salbutamol) nebulized 4–6 hourly or continuous - Consider adding ipratropium bromide (anticholinergic) for additional benefit in severe exacerbations 3. **Systemic corticosteroids** - Oral prednisolone 40–50 mg daily or IV methylprednisolone 1–2 g for 5–7 days - Begin immediately; do not delay **Clinical Pearl:** Ipratropium is added to SABA in severe exacerbations because it provides synergistic bronchodilation via a different mechanism (muscarinic blockade) and reduces hospital admission rates by ~20%. **Key Point:** This patient's PEF of 55% and SpO₂ 92% indicate a severe exacerbation that requires hospital-level care. Outpatient oral steroids alone are insufficient. **Mnemonic:** Severe Asthma = **SOB** (Steroids, Oxygen, Bronchodilators) + **Hospital** **Tip:** Always assess response at 1–2 hours. If PEF improves to >50% and SpO₂ rises to ≥94%, discharge is possible with oral steroids and close follow-up. If no improvement, admit.