What is the initial treatment for an acute asthma exacerbation?

Acute Asthma Exacerbation Management

Subjective

Chief Complaint:

• Document acute onset or worsening of dyspnea, wheezing, chest tightness, and/or cough 1
• Quantify symptom severity: ability to speak in full sentences vs. words only, interference with activities of daily living 1
• Identify triggers: recent upper respiratory infection, allergen exposure, medication non-adherence, or environmental irritants 1
• Review recent SABA use frequency (≥4 times daily suggests poor control and reduced medication effectiveness) 2
• Document nocturnal symptoms, previous severe attacks requiring hospitalization/intubation, and current maintenance therapy 1

Objective

Vital Signs - Critical Severity Markers:

• Severe exacerbation indicators: Respiratory rate >25 breaths/min, heart rate >110 bpm, inability to complete sentences in one breath 1
• Life-threatening features: Silent chest, cyanosis, altered mental status, bradycardia, hypotension, exhaustion, confusion 1
• Oxygen saturation: Target >90% (>95% in pregnancy or cardiac disease) 1, 2

Physical Examination:

• Respiratory effort: accessory muscle use, intercostal retractions, paradoxical breathing 1
• Auscultation: degree of wheezing, air movement quality (silent chest is ominous) 1
• Mental status: drowsiness or confusion indicates impending respiratory failure 1

Objective Measurements:

• Peak expiratory flow (PEF) or FEV₁ before and after initial treatment 1, 2
  • Mild: PEF ≥70% predicted/personal best 1
  • Moderate: PEF 40-69% predicted 1
  • Severe: PEF <40% predicted 1
  • Life-threatening: PEF <33% predicted 1
• Arterial blood gas if severe: PaCO₂ ≥42 mmHg, severe hypoxia (PaO₂ <8 kPa), or low pH indicate critical severity 1

Assessment

Severity Classification:

• Mild exacerbation: Dyspnea only with activity, PEF ≥70%, normal vital signs 1
• Moderate exacerbation: Dyspnea interfering with usual activity, PEF 40-69%, tachypnea/tachycardia 1
• Severe exacerbation: Dyspnea at rest, PEF <40%, respiratory rate >25, heart rate >110 1
• Life-threatening: PEF <33%, silent chest, cyanosis, altered mental status, PaCO₂ ≥42 mmHg 1

Response to Initial Treatment (reassess at 15-30 minutes):

• Good response: PEF ≥70% predicted, minimal symptoms, stable oxygen saturation 1
• Incomplete response: PEF 40-69%, persistent symptoms requiring continued intensive treatment 1
• Poor response: PEF <40%, minimal relief from SABA, consider ICU admission 1

Plan

Immediate Treatment (First Hour)

Oxygen Therapy:

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

First-Line Bronchodilator - Albuterol:

• Nebulizer: 2.5-5 mg every 20 minutes for 3 doses, then 2.5-10 mg every 1-4 hours as needed 1, 2, 3
• MDI with spacer: 4-8 puffs every 20 minutes for up to 3 doses, then as needed (equally effective when properly administered) 1, 2
• For severe exacerbations (PEF <40%), consider continuous nebulization 2, 4

Systemic Corticosteroids - Administer Immediately:

• Adults: Prednisone 40-60 mg PO in single or divided doses 1, 2
• Children: 1-2 mg/kg/day PO (maximum 60 mg/day) 1, 2
• Oral route is as effective as IV and preferred unless patient cannot tolerate PO 1
• Alternative: IV hydrocortisone 200 mg if unable to take oral 1
• Critical pitfall: Do not delay corticosteroids to "try bronchodilators first" 1

Adjunctive Ipratropium Bromide:

• Add to albuterol for all moderate-to-severe exacerbations 1, 2
• Nebulizer: 0.5 mg every 20 minutes for 3 doses, then as needed 1, 2
• MDI: 8 puffs every 20 minutes for 3 doses, then as needed 1, 2
• Reduces hospitalizations, particularly in severe airflow obstruction 1, 5

Reassessment at 15-30 Minutes and After 3 Doses (60-90 minutes)

Measure and document:

• PEF or FEV₁ before and after treatments 1, 2
• Subjective symptom improvement 1
• Vital signs and oxygen saturation 1, 2
• Response to treatment is a better predictor of hospitalization need than initial severity 1, 2

Escalation for Severe/Refractory Cases

Intravenous Magnesium Sulfate:

• Indicated for severe exacerbations (PEF <40%) not responding to initial therapy or life-threatening features 1, 2
• Adults: 2 g IV over 20 minutes 1, 2, 6
• Children: 25-75 mg/kg (maximum 2 g) IV over 20 minutes 1
• Most effective when administered early in treatment course 2, 6

Continuous Albuterol Nebulization:

• Consider for severe exacerbations (FEV₁ or PEF <40%) 1, 2
• More effective than intermittent dosing in severe cases 2, 4

Disposition Criteria

Discharge Home (Good Response):

• PEF ≥70% predicted or personal best 1
• Minimal symptoms, stable oxygen saturation on room air 1
• Stable for 30-60 minutes after last bronchodilator dose 1
• Discharge medications:
  • Continue oral prednisone 40-60 mg daily for 5-10 days (no taper needed for courses <10 days) 1, 2
  • Initiate or continue inhaled corticosteroids 1
  • Provide written asthma action plan and review inhaler technique 1
  • Follow-up with primary care within 1 week 1

Hospital Admission (Incomplete/Poor Response):

• PEF 40-69% with persistent symptoms after 1-2 hours of treatment 1
• PEF <40% after initial treatment 1
• Life-threatening features present 1
• Lower threshold for admission: afternoon/evening presentation, recent nocturnal symptoms, previous severe attacks, poor social circumstances 1

ICU Admission Criteria:

• PEF <33% predicted 1
• Silent chest, altered mental status, minimal relief from frequent SABA 1
• Signs of impending respiratory failure: inability to speak, drowsiness, confusion, worsening fatigue, PaCO₂ ≥42 mmHg 1, 2
• Do not delay intubation once deemed necessary; perform semi-electively before respiratory arrest 1

Critical Pitfalls to Avoid

• Never administer sedatives of any kind 1, 2
• Avoid methylxanthines (theophylline) due to increased side effects without superior efficacy 1, 5
• Do not prescribe antibiotics unless strong evidence of bacterial infection (pneumonia, sinusitis) 1
• Avoid aggressive hydration in older children and adults 1
• Do not underestimate severity—always use objective measurements (PEF/FEV₁) 1
• Be aware of paradoxical bronchospasm with SABA formulations (rare but documented); consider ipratropium if suspected 7