What is the appropriate initial treatment and management for a patient with acute asthma?

Acute Asthma Management

Immediately administer high-flow oxygen (40-60% via face mask) to maintain oxygen saturation >90% (>95% in pregnant patients or those with heart disease), nebulized albuterol 5 mg (or terbutaline 10 mg), and systemic corticosteroids (prednisolone 30-60 mg orally or hydrocortisone 200 mg IV) within the first 15-30 minutes of presentation. 1, 2

Initial Assessment and Severity Recognition

Assess severity objectively using peak expiratory flow (PEF) or FEV₁ measurements, as subjective clinical impression alone frequently underestimates severity—a critical and preventable cause of asthma deaths. 1, 2

Severe exacerbation features include: 3, 2

• Inability to complete sentences in one breath
• Respiratory rate >25 breaths/min
• Heart rate >110 beats/min
• PEF <50% of predicted or personal best

Life-threatening features requiring immediate ICU consideration include: 1, 2

• PEF <33% of predicted or personal best
• Silent chest, cyanosis, or feeble respiratory effort
• Bradycardia, hypotension, or altered mental status (confusion, drowsiness)
• Normal or elevated PaCO₂ (≥42 mmHg) in a breathless patient
• Severe hypoxia (PaO₂ <8 kPa or 60 mmHg)

Immediate Treatment Protocol (First Hour)

Oxygen Therapy

Administer 40-60% oxygen via face mask or nasal cannula to maintain SaO₂ >90% (>95% in pregnant patients or those with cardiac disease), and monitor continuously via pulse oximetry. 1, 2

Bronchodilator Therapy

Administer albuterol 2.5-5 mg via oxygen-driven nebulizer OR 4-8 puffs via metered-dose inhaler (MDI) with spacer every 20 minutes for 3 doses. 1, 2, 4 For children weighing <15 kg, use half doses (2.5 mg). 3 Nebulizer and MDI with spacer are equally effective when properly administered. 1

Systemic Corticosteroids - Critical Early Intervention

Give prednisolone 30-60 mg orally OR IV hydrocortisone 200 mg immediately—do not delay while "trying bronchodilators first." 1, 2, 5 Clinical benefits require a minimum of 6-12 hours to manifest. 5 Oral administration is as effective as intravenous and is preferred unless the patient cannot tolerate oral intake. 1

For children: prednisolone 1-2 mg/kg (maximum 40-60 mg). 3

Adjunctive Ipratropium Bromide

Add ipratropium bromide 0.5 mg to nebulized albuterol every 20 minutes for 3 doses, then as needed, for all moderate to severe exacerbations. 1, 2 This combination reduces hospitalizations, particularly in patients with severe airflow obstruction. 3, 1

Reassessment After Initial Treatment (15-30 Minutes)

Measure PEF or FEV₁ and assess clinical response including respiratory rate, heart rate, oxygen saturation, and ability to speak. 1, 2

If improving (PEF >50-75% predicted): 3

• Continue oxygen 40-60%
• Continue prednisolone 30-60 mg daily (or IV hydrocortisone 200 mg every 6 hours)
• Nebulized beta-agonist every 4-6 hours

If not improving after 15-30 minutes: 3, 2

• Continue oxygen and corticosteroids
• Increase nebulized beta-agonist frequency to every 15-30 minutes (up to continuous nebulization for severe cases)
• Continue ipratropium 0.5 mg every 4-6 hours

Escalation for Severe/Refractory Cases

Intravenous Magnesium Sulfate

Consider IV magnesium sulfate 2 g over 20 minutes for patients with severe exacerbations (PEF <40% predicted after initial treatment) or life-threatening features. 1, 2 This significantly increases lung function and decreases hospitalization necessity. 1

For children: 25-75 mg/kg (maximum 2 g) IV over 20 minutes. 1

Aminophylline (Use with Caution)

Consider IV aminophylline 250 mg over 20 minutes for severe refractory asthma, but never give as a bolus to patients already taking oral theophyllines. 3, 2 Monitor blood concentrations if continued for >24 hours. 3 Note that methylxanthines have increased side effects without superior efficacy compared to standard therapy. 1

Critical Pitfalls to Avoid

• Never administer sedatives of any kind to patients with acute asthma—this is absolutely contraindicated. 3, 1, 2
• Do not delay corticosteroid administration while "trying bronchodilators first"—steroids must be given immediately. 1
• Do not underestimate severity—always measure PEF or FEV₁ objectively, as subjective assessments are frequently inaccurate. 1, 2
• Avoid bolus aminophylline in patients already taking oral theophyllines. 3, 2
• Do not administer IV isoproterenol due to danger of myocardial toxicity. 1

Hospital Admission Criteria

Immediate hospital admission is required for: 3, 1

• Any life-threatening features present
• Features of severe attack persisting after initial treatment
• PEF <50% predicted after 1-2 hours of intensive treatment
• PEF <33% predicted at any time

Lower threshold for admission if: 3

• Presentation in afternoon/evening
• Recent nocturnal symptoms or hospital admission
• Previous severe attacks requiring intubation or ICU admission
• Poor social circumstances or inability to assess own condition

ICU Transfer Criteria

Transfer to ICU accompanied by a physician prepared to intubate if: 3, 1

• Deteriorating PEF despite treatment
• Worsening or persistent hypoxia or hypercapnia
• Exhaustion, feeble respirations, confusion, or drowsiness
• Silent chest with minimal air movement
• PaCO₂ ≥42 mmHg or rising

Discharge Criteria and Planning

Patients may be discharged when: 3, 1

• PEF ≥70% of predicted or personal best
• PEF diurnal variability <25%
• Symptoms minimal or absent
• Oxygen saturation stable on room air
• Patient stable for 30-60 minutes after last bronchodilator dose

At discharge, ensure: 3, 1

• Continuation of oral prednisolone 30-60 mg daily for 5-10 days total (no taper needed for courses <10 days)
• Initiation or increase of inhaled corticosteroids at higher dosage than before admission
• Provision of peak flow meter and written self-management plan
• Verification of proper inhaler technique
• GP follow-up arranged within 1 week
• Respiratory clinic follow-up within 4 weeks

Special Considerations for Children

• Use half doses of bronchodilators (2.5 mg albuterol) for children weighing <15 kg 3
• Prednisolone dosing: 1-2 mg/kg (maximum 40-60 mg) 3
• Blood gas estimations are rarely helpful in deciding initial management in children 3
• Assessment in very young children may be difficult—presence of any severe features should heighten concern 3