What is the recommended management of an acute asthma exacerbation?

Management of Acute Asthma Exacerbation

Immediately administer high-flow oxygen (40-60%) to maintain SaO₂ >90%, nebulized albuterol 5 mg (or 4-8 puffs via MDI with spacer), and systemic corticosteroids (prednisolone 30-60 mg orally or IV hydrocortisone 200 mg) within the first 15-30 minutes—these three interventions form the cornerstone of acute asthma management and must not be delayed. 1, 2

Initial Assessment and Severity Recognition

Assess severity objectively within 15-30 minutes using peak expiratory flow (PEF) or FEV₁, as underestimation due to inadequate objective measurements is the most common preventable cause of asthma deaths. 3, 1

Severe Exacerbation Features:

• Inability to complete sentences in one breath 3
• Respiratory rate >25 breaths/min 3
• Heart rate >110 beats/min 3
• PEF <50% of predicted or personal best 3

Life-Threatening Features Requiring Immediate ICU Consideration:

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

Immediate Treatment Protocol (First Hour)

Oxygen Therapy:

• Administer 40-60% oxygen via face mask or nasal cannula 3
• Target SaO₂ >90% (>95% in pregnant patients or those with cardiac disease) 1, 2

Bronchodilator Therapy:

• Nebulized albuterol 5 mg or terbutaline 10 mg every 20 minutes for 3 doses 3, 1
• Alternative: 4-8 puffs via MDI with spacer every 20 minutes for 3 doses 1, 2
• For children <15 kg: use half doses (2.5 mg salbutamol) 3

Systemic Corticosteroids (Must Be Given Immediately):

• Adults: Prednisolone 30-60 mg orally OR IV hydrocortisone 200 mg 3
• Children: Prednisolone 1-2 mg/kg (maximum 40 mg) 3
• Oral administration is as effective as IV and is preferred unless the patient cannot tolerate oral intake 2
• Clinical benefits require 6-12 hours minimum to manifest 1

Add Ipratropium Bromide for All Moderate-to-Severe Exacerbations:

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

Reassessment at 15-30 Minutes After Initial Treatment

Measure PEF or FEV₁ and evaluate symptoms and vital signs to guide further management. 1, 2

Good Response (PEF >75% predicted):

• Step up usual maintenance treatment 3
• Continue monitoring with PEF chart 3
• Arrange follow-up within 48 hours 3

Incomplete Response (PEF 50-75% predicted):

• Give prednisolone 30-60 mg if not already administered 3
• Continue nebulized beta-agonist every 4-6 hours 3
• Consider hospital admission if more than one severe feature persists 3

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

• Continue oxygen and increase nebulized beta-agonist frequency to every 15-30 minutes 3
• Repeat ipratropium 0.5 mg every 20 minutes for additional doses 3
• Arrange immediate hospital admission 3

Adjunctive Therapies for Severe/Refractory Cases

Intravenous Magnesium Sulfate:

• Indicated for severe exacerbations with PEF <40% after initial treatment or life-threatening features 1, 2
• Dose: 2 g IV over 20 minutes for adults; 25-75 mg/kg (maximum 2 g) for children 1, 2
• Significantly increases lung function and decreases hospitalization necessity 1

Intravenous Aminophylline or Beta-Agonists:

• Consider IV aminophylline 250 mg over 20 minutes OR IV salbutamol/terbutaline 250 µg over 10 minutes for life-threatening features 3
• Do NOT give bolus aminophylline to patients already taking oral theophyllines 3, 4
• Note: Most studies show aminophylline adds little benefit and increases adverse effects; reserve for truly refractory cases 4

Critical Pitfalls to Avoid

• Never administer sedatives of any kind to patients with acute asthma—this is absolutely contraindicated 3, 1
• Do not delay corticosteroid administration while "trying bronchodilators first"—steroids must be given immediately 1, 2
• Do not underestimate severity—always measure PEF or FEV₁ objectively, as subjective assessments are frequently inaccurate 3, 1
• Avoid methylxanthines (theophylline) due to increased side effects without superior efficacy over standard therapy 1, 4
• Do not give bolus aminophylline to patients on oral theophyllines 3, 4

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 <33% predicted after treatment
• PEF <50% predicted after 1-2 hours of intensive treatment

Lower threshold for admission if: 3

• Presentation in afternoon or evening rather than morning
• Recent nocturnal symptoms or worsening symptoms
• Previous severe attacks, especially requiring intubation or ICU admission
• Recent hospitalization or ED visit within past month
• Poor social circumstances or inability to assess symptom severity

ICU Transfer Criteria

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

• Deteriorating PEF or worsening exhaustion
• Feeble respirations or persistent/worsening hypoxia
• PaCO₂ ≥42 mmHg or rising
• Confusion, drowsiness, or altered mental status
• Coma or respiratory arrest

Discharge Criteria (After Stabilization)

Patients may be discharged when: 1, 2

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

At discharge, ensure: 3, 1

• Continue oral corticosteroids for 5-10 days (no taper needed for courses <10 days) 1, 2
• Initiate or continue inhaled corticosteroids 1, 2
• Inhaler technique verified and recorded 3
• Provide written asthma action plan 1, 2
• Arrange GP follow-up within 1 week 3
• Arrange specialist follow-up within 4 weeks 3

Special Considerations for Children

• Use half doses of bronchodilators (2.5 mg salbutamol or 5 mg terbutaline) for children <15 kg 3
• Prednisolone dosing: 1-2 mg/kg (maximum 40-60 mg) 3
• Blood gas estimations are rarely helpful in deciding initial management for children 1