Acute Asthma Exacerbation (Adults) 🫁
Adult acute asthma per BTS/SIGN QRG (SIGN 158): PEF severity, oxygen, bronchodilators, steroids, magnesium, admission, ICU, and follow-up.
📖 Overview
- Adults (and adolescents on adult pathways). Children: see separate QRG pages.
- Classify severity early (PEF % best, or % predicted if best unknown, plus clinical features). Treat immediately; do not wait for investigations.
- Follow local Trust asthma / ED protocols for continuous nebs, IV therapy, and ICU.
🔍 Initial Assessment
- ABCDE. Severe features: severe breathlessness (including inability to complete sentences), tachypnoea, tachycardia, silent chest, cyanosis, or collapse. None is specific; absence does not exclude severe attack.
- PEF or FEV₁: % previous best preferred; % predicted if best unknown. Do not delay O₂ or bronchodilators for PEF if too breathless.
- SpO₂: aim 94–98%; guides O₂ and need for ABG. ABG if SpO₂ <92% or other life-threatening features.
- History: controllers/relievers, recent oral steroids, previous ICU/near-fatal attack, triggers, pregnancy, psychosocial factors. Severe asthma plus adverse psychosocial factors raises risk of death.
📊 Severity Classification (BTS/SIGN)
- Grade by the worst feature present. Any one criterion is enough. Life-threatening features apply in a patient already with severe asthma.
Moderate acute
- PEF (% best or predicted)
- >50–75%
- Clinical features (any one)
- Increasing symptoms; no features of acute severe asthma
Acute severe
- PEF (% best or predicted)
- 33–50%
- Clinical features (any one)
- RR ≥25/min; HR ≥110/min; inability to complete sentences in one breath
Life-threatening
- PEF (% best or predicted)
- <33%
- Clinical features (any one)
- SpO₂ <92%; PaO₂ <8 kPa; “normal” PaCO₂ (4.6–6.0 kPa); altered conscious level; exhaustion; arrhythmia; hypotension; cyanosis; silent chest; poor respiratory effort
Near-fatal
- PEF (% best or predicted)
- N/A
- Clinical features (any one)
- Raised PaCO₂ and/or mechanical ventilation with raised inflation pressures
| Severity | PEF (% best or predicted) | Clinical features (any one) |
|---|---|---|
| Moderate acute | >50–75% | Increasing symptoms; no features of acute severe asthma |
| Acute severe | 33–50% | RR ≥25/min; HR ≥110/min; inability to complete sentences in one breath |
| Life-threatening | <33% | SpO₂ <92%; PaO₂ <8 kPa; “normal” PaCO₂ (4.6–6.0 kPa); altered conscious level; exhaustion; arrhythmia; hypotension; cyanosis; silent chest; poor respiratory effort |
| Near-fatal | N/A | Raised PaCO₂ and/or mechanical ventilation with raised inflation pressures |
💊 Immediate Management (all acute attacks)
- O₂: controlled supplementary O₂ for hypoxaemia in acute severe asthma; target SpO₂ 94–98%. Start O₂ even if oximetry not yet available; monitor SpO₂ ASAP.
- β₂ agonist: high-dose inhaled, as early as possible. Prefer O₂-driven nebuliser in hospital/ambulance/primary care; use neb (O₂-driven) if acute severe or life-threatening. If poor response to initial bolus, consider continuous nebulisation. Reserve IV β₂ agonist when inhaled therapy cannot be used reliably.
- Steroids for all acute attacks: prednisolone 40–50 mg daily until recovery (minimum 5 days).
- Repeat bronchodilator to response.
🚨 Acute Severe / Life-Threatening Add-Ons
- Add nebulised ipratropium 0.5 mg 4–6 hourly for acute severe or life-threatening asthma, or poor initial β₂ agonist response.
- Consider single-dose IV MgSO₄ 1.2–2 g over 20 minutes if PEF <50% best/predicted and poor initial bronchodilator response; senior discussion first. Nebulised MgSO₄ not recommended in adults.
- No routine antibiotics. Do not sedate unless needed for anaesthetic / ICU procedures.
🔬 Investigations & Monitoring
- Repeat PEF after bronchodilator and at intervals; chart response. Continuous SpO₂; aim 94–98%.
- CXR not routine unless suspected pneumomediastinum/pneumothorax, consolidation, life-threatening asthma, poor response, or ventilation needed.
- Exhaustion, rising PaCO₂, falling SpO₂, or deteriorating PEF: escalate to ICU.
🏥 Admission, Discharge & ICU
- Admit: any life-threatening or near-fatal feature; or any severe feature persisting after initial treatment.
- May discharge from ED if PEF >75% best/predicted one hour after initial treatment, unless other reasons favour admission.
- ICU if ventilatory support needed, or acute severe / life-threatening asthma failing therapy: deteriorating PEF; persisting/worsening hypoxia; hypercapnia; falling pH or rising H⁺; exhaustion/feeble respiration; drowsiness/confusion/altered consciousness; respiratory arrest.
🏠 Follow-Up After ED / Hospital
- Inform primary care within 24 hours of ED or hospital discharge.
- Near-fatal: specialist supervision indefinitely. Severe attack requiring admission: respiratory follow-up for at least one year.
- Before discharge: ICS + reliever supply, inhaler technique, written asthma action plan where possible.
Note Template
Ready-to-use clinical note structure
🕒 08 / 10 / 2026 — 16:09 ATRP re: acute asthma exacerbation Patient: [age] [sex] Admission Dx: [reason for admission] PMHx: asthma [mild / moderate / severe]; previous near-fatal / ICU [Y/N]; recent ED/hospital [Y/N] 🧾 Hx: • Onset / trigger: [infection / allergen / NSAID / other / unknown] • Usual inhalers: [ICS / ICS-LABA / SABA]; oral steroids recently [Y/N] • Ability to speak: [sentences / phrases / words] • Smoking / adherence concerns: [ ] 🩺 Exam: • RR: __ SpO₂: __% on __ HR: __ BP: __ GCS / alertness: __ • PEF: __ L/min (__% best / predicted); best known: __ • Life-threatening features: [none / SpO₂<92% / silent chest / list] • Chest: [wheeze / silent chest / accessory muscles / cyanosis] 🔬 Investigations: • ABG: [if done — PaO₂ / PaCO₂ / pH] • K⁺: __ CXR: [not indicated / findings] 📋 Impression: Acute asthma — [mild / moderate / acute severe / life-threatening / near-fatal] (NCEC No. 14) 📌 Plan: • O₂ to SpO₂ 94–98% • Salbutamol [spacer puffs / neb 5 mg O₂-driven]; repeat __ • Ipratropium 0.5 mg neb [Y/N] • Prednisolone 40–50 mg PO; course __ days (minimum 5) • MgSO₄ IV [given / considered / N/A — senior discussion if used] • Admit / discharge: [observe / admit / HDU-ICU]; senior informed [Y/N] • Discharge checklist if applicable: ICS + SABA supply, inhaler technique, action plan, GP informed ≤24 h (BTS/SIGN), GP review [≤2 working days if ≥moderate / ≤2 weeks if mild — HSE NCP], respiratory follow-up within 4 weeks (HSE NCP) 👤 [Your Name], [Role] IMC: _______
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