Severity Classification: Life-Threatening Asthma Exacerbation
This patient with a PEFR of 140 (25% of personal best of 550) meets criteria for life-threatening asthma and requires immediate emergency department evaluation and likely hospitalization. 1
Calculation and Classification
The patient's current PEFR represents 25% of her personal best (140/550 = 0.25 or 25%). 1
According to the British Thoracic Society guidelines, asthma exacerbation severity is classified as follows:
- Life-threatening features: PEFR <33% of predicted normal or personal best 1
- Severe features: PEFR <50% of predicted normal or personal best 1
- Moderate features: PEFR 40-69% of predicted or personal best 1
At 25% of personal best, this patient falls well below the 33% threshold, definitively placing her in the life-threatening category. 1
Additional Life-Threatening Features to Assess
Beyond the PEFR measurement, immediately evaluate for other life-threatening signs: 1
- Silent chest, cyanosis, or feeble respiratory effort
- Bradycardia or hypotension
- Exhaustion, confusion, or coma
- Inability to speak (too dyspneic to complete sentences)
- Arterial blood gas showing normal or elevated PaCO2 (5-6 kPa or higher) in a breathless patient
Immediate Management Required
This patient requires emergency treatment initiated immediately: 1
- High-dose inhaled beta-agonists: Salbutamol 5 mg or terbutaline 10 mg nebulized with oxygen 1
- High-dose systemic corticosteroids: Prednisolone 30-60 mg orally or hydrocortisone 200 mg IV 1
- Ipratropium bromide: 0.5 mg nebulized added to beta-agonist for life-threatening features 1
- Consider IV aminophylline (250 mg over 20 minutes) or IV salbutamol/terbutaline (250 µg over 10 minutes) 1
- Supplemental oxygen to maintain adequate saturation 1
Critical Distinction from Other Severity Categories
The 2007 Expert Panel Report 3 provides additional context showing that PEFR <25% of personal best represents a "subset: life-threatening" category requiring ED hospitalization and possible ICU admission. 1 This aligns with the British Thoracic Society's <33% threshold for life-threatening disease. 1
Common pitfall: Do not confuse this with "severe" asthma (which would be PEFR 33-49% of personal best) or "moderate" asthma (PEFR 40-69%). 1 At 25%, this patient is clearly in the most critical category requiring the most aggressive intervention.