What is the appropriate management of an acute asthma exacerbation?

Management of Acute Asthma Exacerbation

Immediately administer oxygen to maintain SaO₂ >90%, nebulized albuterol 5 mg every 20 minutes for three doses, and systemic corticosteroids (prednisolone 30–60 mg orally or hydrocortisone 200 mg IV) within the first 15–30 minutes—failure to provide objective severity assessment and prompt corticosteroids are the most common preventable causes of asthma deaths. 1

Initial Severity Assessment (First 15–30 Minutes)

Objective measurement of peak expiratory flow (PEF) or FEV₁ is mandatory and must not be delayed, as subjective assessment alone leads to fatal underestimation of severity. 1, 2

Moderate exacerbation:

• Able to speak complete sentences in one breath
• Heart rate <110 beats/min, respiratory rate <25 breaths/min
• PEF 50–75% of predicted or personal best 2, 3

Severe exacerbation:

• Cannot complete sentences in one breath
• Heart rate >110 beats/min, respiratory rate >25 breaths/min
• PEF <50% of predicted or personal best 1, 2, 3

Life-threatening features (immediate ICU consideration):

• Silent chest, cyanosis, feeble respiratory effort
• Bradycardia, hypotension, exhaustion, confusion, or coma
• PEF <33% of predicted
• Normal or elevated PaCO₂ ≥42 mmHg in a breathless patient
• Severe hypoxia (PaO₂ <8 kPa) despite oxygen 1, 3

Immediate Treatment Protocol (First Hour)

Oxygen Therapy

Deliver 40–60% oxygen via face mask or nasal cannula targeting SaO₂ >90% (>95% in pregnancy or cardiac disease). 1, 2, 3 Oxygen does not worsen CO₂ retention in asthma, unlike in COPD. 4

Bronchodilator Therapy

• Nebulized albuterol 5 mg (or terbutaline 10 mg) every 20 minutes for three doses in the first hour 1, 2, 3
• For children <15 kg, use half the adult dose (2.5 mg albuterol) 1
• Alternative: 4–8 puffs via metered-dose inhaler with spacer every 20 minutes if nebulizer unavailable 2, 3

Systemic Corticosteroids (Must Be Given Immediately)

Do not delay corticosteroids while "trying bronchodilators first"—this is a critical error. 1

• Adults: Prednisolone 30–60 mg orally OR IV hydrocortisone 200 mg 1, 2, 3
• Children: Prednisolone 1–2 mg/kg (maximum 40 mg) 1
• Oral and IV routes are equally effective; prefer oral when tolerated 1, 3

Ipratropium Bromide

Add ipratropium 0.5 mg to nebulizer (or 8 puffs via MDI) every 20 minutes for three doses in all moderate-to-severe exacerbations—this reduces hospitalization risk. 5, 1, 3

Reassessment at 15–30 Minutes After Initial Treatment

Re-measure PEF/FEV₁ and vital signs to guide next steps. 1, 2

Good Response (PEF >75% predicted)

• Step up usual maintenance inhaled corticosteroid therapy
• Continue monitoring with PEF chart
• Arrange follow-up within 48 hours 1, 2

Incomplete Response (PEF 50–75% predicted)

• Continue nebulized β-agonist every 4–6 hours
• Ensure oral corticosteroids have been administered
• Consider hospital admission if severe features persist 1, 2, 3

Poor Response (PEF <50% predicted or persistent severe features)

• Increase nebulized β-agonist frequency to every 15–30 minutes
• Repeat ipratropium 0.5 mg every 20 minutes
• Arrange immediate hospital admission 1, 2

Adjunctive Therapies for Refractory/Life-Threatening Cases

Intravenous Magnesium Sulfate

Administer 2 g IV over 20 minutes for severe exacerbations (PEF <40%) not responding to initial treatment or with life-threatening features. 1, 3 Nine international guidelines support this intervention. 5

Aminophylline or IV Beta-Agonists

• IV aminophylline 250 mg over 20 minutes OR IV salbutamol/terbutaline 250 µg over 10 minutes for life-threatening features 1, 3
• Never give aminophylline bolus to patients already on oral theophyllines 1
• Routine methylxanthine use is discouraged due to increased side effects without superior efficacy 1

Critical Pitfalls to Avoid

Sedatives are absolutely contraindicated in acute asthma and must never be administered under any circumstances. 1

Additional pitfalls:

• Never rely solely on subjective assessment—objective PEF/FEV₁ is essential 1
• Do not delay corticosteroids while attempting bronchodilator therapy alone 1
• Do not use antibiotics routinely—three guidelines discourage their use unless complications are present 5
• Doubling inhaled corticosteroid doses during exacerbations is ineffective 5

Hospital Admission Criteria

Immediate admission required for:

• Any life-threatening feature present
• Severe asthma persisting after initial therapy
• PEF <33% predicted after treatment
• PEF <50% predicted after 1–2 hours of intensive therapy 1, 2, 3

Lower threshold for admission when:

• Presentation occurs in afternoon/evening
• Recent nocturnal or worsening symptoms
• Prior severe attacks requiring intubation/ICU
• ≥2 hospitalizations or ≥3 emergency visits in past year
• Poor social circumstances limiting reliable monitoring 5, 1, 3

ICU Transfer Criteria

Transfer to ICU when:

• Deteriorating PEF despite treatment or exhaustion
• Feeble respirations or worsening hypoxia
• PaCO₂ ≥42 mmHg or rising
• Altered mental status, coma, or respiratory arrest
• Silent chest with cyanosis 1, 3

Discharge Criteria

Patients may be discharged when:

• PEF >75% of predicted or personal best
• Diurnal PEF variability <25%
• Symptoms minimal or absent
• SaO₂ stable on room air
• Stable for 30–60 minutes after last bronchodilator dose 1, 2, 3

Discharge Planning

• Continue oral corticosteroids for 5–10 days (no taper needed for courses <10 days) 1
• Ensure ongoing inhaled corticosteroid therapy or initiate if not already prescribed 1, 3
• Verify and document correct inhaler technique 1, 3
• Provide written asthma action plan and peak-flow meter 1, 3
• Arrange follow-up with primary care within 1 week and specialist within 4 weeks 1, 3

Risk Factors for Asthma-Related Death

Identify high-risk patients:

• Previous severe exacerbation (intubation or ICU admission)
• ≥2 hospitalizations or >3 ED visits in past year
• Use of >2 canisters of short-acting β-agonist per month
• Difficulty perceiving airway obstruction severity
• Low socioeconomic status or inner-city residence
• Major psychosocial problems or psychiatric disease
• Comorbidities (cardiovascular disease, chronic lung disease) 5