What is the management approach for acute exacerbation of asthma?

Management of Acute Asthma Exacerbation

Immediately administer oxygen to maintain SaO₂ >90% (>95% in pregnant patients or those with heart disease), start albuterol 2.5-5 mg via nebulizer or 4-8 puffs via MDI with spacer every 20 minutes for 3 doses, and give oral prednisone 40-60 mg within the first hour of presentation. 1, 2, 3

Initial Assessment and Severity Classification

Classify exacerbation severity within the first 15-30 minutes based on symptoms, physical examination, and objective measurements 4, 1:

• Mild exacerbation: Dyspnea only with activity, PEF ≥70% predicted, speaks in sentences, respiratory rate increased minimally 1, 3
• Moderate exacerbation: Dyspnea interferes with usual activity, PEF 40-69% predicted, speaks in phrases, respiratory rate >25 breaths/min, heart rate >110 bpm 1, 3
• Severe exacerbation: Dyspnea at rest, PEF <40% predicted, speaks in words only, respiratory rate >30 breaths/min, use of accessory muscles 1, 3
• Life-threatening features: PEF <33% predicted, silent chest, cyanosis, altered mental status, PaCO₂ ≥42 mmHg, inability to speak, bradycardia, exhaustion 1, 3

Critical pitfall: The severity of asthma attacks is often underestimated by patients, relatives, and physicians due to failure to make objective measurements with PEF or FEV₁ 1. Always obtain objective lung function measurements before and after treatment 1, 3.

Primary Treatment Protocol

Oxygen Therapy

Administer supplemental oxygen immediately via nasal cannula or mask to maintain SaO₂ >90% (>95% in pregnant patients or those with heart disease) 1, 2, 3. Monitor oxygen saturation continuously until clear response to bronchodilator therapy occurs 1, 2.

Bronchodilator Therapy - First-Line Treatment

Albuterol (short-acting β2-agonist) is the cornerstone of acute treatment 1, 2, 3:

• Nebulizer dosing: 2.5-5 mg every 20 minutes for 3 doses, then 2.5-10 mg every 1-4 hours as needed 1, 2, 5
• MDI with spacer dosing: 4-8 puffs every 20 minutes for up to 3 doses, then as needed 1, 2, 3
• For severe exacerbations (PEF <40%): Consider continuous nebulization of albuterol rather than intermittent dosing 2, 3

MDI with spacer is equally effective as nebulizer therapy when properly administered and may be preferred in some settings 1, 6.

Systemic Corticosteroids - Critical Early Intervention

Administer systemic corticosteroids within the first hour of presentation for all moderate to severe exacerbations 1, 2, 3:

• Adults: Prednisone 40-60 mg orally in single or divided doses 1, 2, 3
• Children: 1-2 mg/kg/day orally (maximum 60 mg/day) 1, 2, 3
• Alternative if unable to take oral: IV hydrocortisone 200 mg or IV methylprednisolone 1-2 mg/kg 1, 3

Oral administration is as effective as intravenous and is preferred unless the patient cannot tolerate oral intake 1, 2. Early administration within one hour decreases hospitalization rates, with the most pronounced effect in severe exacerbations 6, 7.

Reassessment After Initial Treatment

Reassess the patient 15-30 minutes after starting treatment and after 3 doses of bronchodilator (60-90 minutes total) 1, 2, 3:

• Measure PEF or FEV₁ before and after each treatment 1, 2
• Assess symptoms, vital signs, and oxygen saturation 1, 2
• Response to treatment is a better predictor of hospitalization need than initial severity 1, 2

Adjunctive Therapies for Moderate to Severe Exacerbations

Ipratropium Bromide

Add ipratropium bromide to albuterol for all moderate to severe exacerbations 1, 2, 3:

• Dosing: 0.5 mg via nebulizer or 8 puffs via MDI every 20 minutes for 3 doses, then as needed 1, 2, 3
• This combination reduces hospitalizations, particularly in patients with severe airflow obstruction 1, 6

Intravenous Magnesium Sulfate

Consider magnesium sulfate for severe exacerbations not responding to initial therapy or life-threatening presentations 1, 2, 3:

• Adult dosing: 2 g IV over 20 minutes 1, 2, 3
• Pediatric dosing: 25-75 mg/kg up to 2 g maximum 1
• Most effective when administered early in the treatment course 2, 8

Treatment Duration and Monitoring

Continue treatment for 5-10 days with oral corticosteroids after discharge, with no tapering necessary for courses less than 10 days 1, 9. Observe patients for 30-60 minutes after the last bronchodilator dose to ensure stability before discharge 1.

Hospital Admission Criteria

Admit to hospital if any of the following are present 1, 3:

• Life-threatening features persist after initial treatment 1, 3
• PEF remains <50% predicted after 1-2 hours of intensive treatment 1
• Severe exacerbation features persist after 3 doses of bronchodilator 1, 3
• Lower threshold for admission with recent nocturnal symptoms, previous severe attacks, afternoon/evening presentation, or concerning social circumstances 1, 3

Discharge Criteria

Patients may be discharged when 1, 3:

• PEF reaches ≥70% of predicted or personal best 1, 3
• Symptoms are minimal or absent 1
• Oxygen saturation is stable on room air 1
• Patient demonstrates proper inhaler technique 1

Critical Pitfalls to Avoid

Never administer sedatives of any kind to patients with acute asthma exacerbation 1, 2. Avoid methylxanthines (theophylline) due to increased side effects without superior efficacy 1, 8. Do not use aggressive hydration in older children and adults 1. Antibiotics are not recommended unless there is strong evidence of bacterial infection such as pneumonia or sinusitis 1, 3.

Do not delay intubation once it is deemed necessary - it should be performed semi-electively before respiratory arrest occurs 1. Monitor for signs of impending respiratory failure: inability to speak, altered mental status, intercostal retraction, worsening fatigue, and PaCO₂ ≥42 mmHg 1, 2.

Discharge Planning

Provide a written asthma action plan and review inhaler technique before discharge 1. Continue or initiate inhaled corticosteroids at discharge 1, 3. Arrange follow-up with primary care within 1 week and specialist clinic within 4 weeks 1. For patients at high risk of non-adherence, consider an IM depot corticosteroid injection at discharge 1.