What are the grades of asthma exacerbation and their corresponding treatments?

Grades of Asthma Exacerbation

Asthma exacerbations are classified into two grades: severe and moderate, with no formal "mild" exacerbation category recognized by current guidelines. 1

Classification System

Severe Exacerbations

Severe exacerbations require urgent action to prevent hospitalization or death from asthma. 1 These are defined by:

• Use of systemic corticosteroids (tablets, suspension, or injections) 1
• Emergency room visits or hospitalizations 1
• Peak expiratory flow (PEF) decline of 20-30% from baseline 1
• Life-threatening features including PEF <33% predicted, silent chest, cyanosis, altered mental status, feeble respiratory effort, bradycardia, hypotension, exhaustion, confusion, or coma 2, 3
• Arterial blood gas markers showing normal/high PaCO₂ (≥42 mmHg) in a breathless patient, severe hypoxia (PaO₂ <8 kPa), or low pH 2

Moderate Exacerbations

Moderate exacerbations are troublesome to patients and prompt treatment changes, but are not severe. 1 These are clinically identified by:

• Being outside the patient's usual range of day-to-day asthma variation 1
• Deterioration in symptoms, lung function, and increased rescue bronchodilator use lasting 2 days or more 2
• PEF 40-69% of predicted or personal best 4
• Dyspnea interfering with usual activity 4

Why No "Mild" Exacerbation Grade Exists

The American Thoracic Society/European Respiratory Society Task Force deliberately excluded a "mild" exacerbation category because these episodes are only just outside the normal range of variation and cannot be distinguished from transient loss of asthma control with present methods of analysis. 1

Clinical Assessment Framework

Severity Indicators by Age (≥12 years)

The severity classification uses both impairment and risk domains 1:

Impairment Domain:

• Symptoms: ≤2 days/week (intermittent) to throughout the day (severe persistent) 1
• Nighttime awakenings: ≤2 times/month (intermittent) to often 7 times/week (severe persistent) 1
• Short-acting β2-agonist use: ≤2 days/week (intermittent) to several times per day (severe persistent) 1
• FEV₁: >80% predicted (mild) to <60% predicted (severe) 1

Risk Domain:

• Exacerbations requiring oral systemic corticosteroids: 0-1/year (intermittent/mild) to ≥2/year (moderate/severe persistent) 1
• Patients with ≥2 exacerbations requiring oral corticosteroids in the past year are considered to have persistent asthma, even if impairment categories suggest intermittent asthma 1

Treatment Approach by Exacerbation Grade

Severe Exacerbations - Immediate Management

Administer oxygen to maintain SaO₂ >90% (>95% in pregnant patients or those with heart disease) 4, 2, 3

Primary bronchodilator therapy:

• Albuterol 2.5-5 mg via nebulizer every 20 minutes for 3 doses, then 2.5-10 mg every 1-4 hours as needed 4, 2
• OR 4-8 puffs via MDI with spacer every 20 minutes for up to 3 doses 4, 2
• For severe exacerbations (PEF <40%), continuous albuterol administration may be more effective 4, 2

Systemic corticosteroids - administer early:

• Adults: Prednisone 40-60 mg orally in single or divided doses 4, 2
• Children: 1-2 mg/kg/day (maximum 60 mg/day) 4, 2
• Oral administration is as effective as IV and less invasive 2

Add ipratropium bromide for all severe exacerbations:

• 0.5 mg via nebulizer or 8 puffs via MDI every 20 minutes for 3 doses, then as needed 4, 2
• This combination reduces hospitalizations, particularly in severe airflow obstruction 2

Consider IV magnesium sulfate for refractory cases:

• 2g IV over 20 minutes for adults 4, 2
• 25-75 mg/kg (maximum 2g) for children 2
• Most effective when administered early in severe refractory asthma 4

Moderate Exacerbations - Management

Initiate SABA via nebulizer or MDI with spacer 2

Administer oral corticosteroids:

• Same dosing as severe exacerbations 2
• Duration of 5-10 days for outpatient "burst" therapy 2
• No tapering necessary for courses <10 days 2

Add ipratropium bromide 2

Provide oxygen supplementation to maintain saturation >92-95% 2

Critical Reassessment Points

Reassess patients 15-30 minutes after starting treatment:

• Measure PEF or FEV₁ before and after treatments 4, 2
• Assess symptoms and vital signs 4, 2
• Response to treatment is a better predictor of hospitalization need than initial severity 4, 2

Good response (discharge criteria):

• PEF ≥70% of predicted or personal best 2
• Minimal or absent symptoms 2
• Stable for 30-60 minutes after last bronchodilator dose 2

Incomplete response (hospital ward admission):

• PEF 40-69% predicted with persistent symptoms 2

Poor response (ICU consideration):

• PEF <40% predicted 2
• Life-threatening features present 2

Common Pitfalls to Avoid

Never administer sedatives of any kind to patients with acute asthma exacerbation - this is absolutely contraindicated 4, 2, 3

Do not delay corticosteroid administration while "trying bronchodilators first" - steroids must be given immediately as clinical benefits require 6-12 hours minimum 2, 3

Do not underestimate severity - always measure PEF or FEV₁ objectively, as subjective assessments by patients, families, and clinicians are frequently inaccurate 2, 3

Avoid bolus aminophylline in patients already taking oral theophyllines 2

Monitor for impending respiratory failure: inability to speak, altered mental status, intercostal retraction, worsening fatigue, PaCO₂ ≥42 mmHg 4, 2