What is the management of an acute exacerbation of bronchial asthma?

Management of Acute Exacerbation of Bronchial Asthma

For acute asthma exacerbations, immediately administer high-flow oxygen to maintain SaO₂ >90%, nebulized albuterol 2.5-5 mg every 20 minutes for 3 doses, and oral prednisolone 40-60 mg (or IV hydrocortisone 200 mg) within the first hour, with ipratropium bromide 0.5 mg added for all moderate-to-severe cases. 1, 2, 3

Causes and Triggers

Acute asthma exacerbations represent reactions to airway irritants or failures of chronic maintenance therapy. 4 Common triggers include:

• Respiratory infections (viral or bacterial) 1
• Allergen exposure in sensitized patients 1
• Environmental irritants (smoke, pollution, noxious gases) 5
• Medication non-adherence or inadequate maintenance therapy 1
• Aspirin or NSAIDs in aspirin-sensitive patients 5

Initial Assessment and Severity Classification

Assess severity immediately using objective measurements—failure to do so is a common cause of preventable asthma deaths. 3

Severe Exacerbation Features:

• Inability to complete sentences in one breath 1, 3
• Respiratory rate >25 breaths/min 1, 3
• Heart rate >110 beats/min 1, 3
• PEF <50% of predicted or personal best 1, 3

Life-Threatening Features (Require Immediate ICU Consideration):

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

Immediate Management Algorithm

First 15-30 Minutes:

1. Oxygen Therapy:

• Administer high-flow oxygen at 40-60% via face mask or nasal cannula 3
• Target SaO₂ >90% (>95% in pregnant patients or those with heart disease) 1, 2, 3
• Monitor oxygen saturation continuously until clear response to bronchodilator therapy 1, 2

2. Bronchodilator Therapy:

• Albuterol 2.5-5 mg via nebulizer OR 4-8 puffs via MDI with spacer every 20 minutes for 3 doses 1, 2, 3
• MDI with spacer is equally effective as nebulizer therapy in adults and children 6
• For severe exacerbations with FEV₁ or PEF <40% predicted, consider continuous nebulization 3, 7

3. Ipratropium Bromide (Add 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, 3
• Combination therapy reduces hospitalizations by 28% compared to SABA alone (RR 0.72,95% CI 0.59-0.87) 8
• Most effective in patients with severe airflow obstruction 1, 8

4. Systemic Corticosteroids (Administer Immediately—Do NOT Delay):

• Prednisolone 40-60 mg orally OR hydrocortisone 200 mg IV 1, 2, 3
• Oral administration is as effective as IV and less invasive 1
• Clinical benefits require 6-12 hours minimum, so early administration is critical 3
• Administration within 1 hour of presentation decreases hospitalization need 6

Reassessment at 15-30 Minutes:

• Measure PEF or FEV₁ after initial treatment 1, 2, 3
• Assess symptoms, vital signs, and oxygen saturation 1, 2
• Response to treatment is a better predictor of hospitalization need than initial severity 1

Treatment Based on Response

Good Response (PEF ≥70% predicted, minimal symptoms):

• Continue oxygen until stable 1
• Continue albuterol 2.5-10 mg every 1-4 hours as needed 1
• Continue prednisolone 40-60 mg daily for 5-10 days (no taper needed for courses <10 days) 1, 5
• Observe for 30-60 minutes after last bronchodilator dose before discharge 1

Incomplete Response (PEF 40-69% predicted, persistent symptoms):

• Continue intensive treatment 1
• Give nebulized beta-agonists more frequently, up to every 15 minutes 1
• Continue ipratropium every 4-6 hours 1
• Admit to hospital ward 1

Poor Response (PEF <40% predicted after 1 hour):

• Consider IV magnesium sulfate 2 g over 20 minutes 1, 2, 3
• Magnesium significantly increases lung function and decreases hospitalization necessity 6, 8
• Admit to hospital; consider ICU if life-threatening features present 1

Adjunctive Therapies for Severe/Refractory Cases

Intravenous Magnesium Sulfate:

• Indicated for severe exacerbations with FEV₁ or 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
• Causes bronchial smooth muscle relaxation with minor side effects 1

Critical Pitfalls to Avoid

1. Never Administer Sedatives:

• Sedatives of any kind are absolutely contraindicated in acute asthma 1, 3

2. Do Not Delay Corticosteroids:

• Corticosteroids must be given immediately, not after "trying bronchodilators first" 1

3. Avoid Methylxanthines (Theophylline):

• Increased side effects without superior efficacy 1, 7
• Do not give bolus aminophylline to patients already taking oral theophyllines 1

4. Do Not Underestimate Severity:

• Always measure PEF or FEV₁—patients, families, and clinicians frequently fail to recognize dangerous exacerbations 1, 3

5. Antibiotics Not Routinely Indicated:

• Only prescribe if strong evidence of bacterial infection (pneumonia or sinusitis) 1, 7

6. Do Not Delay Intubation:

• Once respiratory failure is deemed imminent, intubation should be performed semi-electively before respiratory arrest 1
• Warning signs: drowsiness, confusion, inability to speak, silent chest, PaCO₂ ≥42 mmHg 1

Hospital Admission Criteria

Immediate Hospital Admission Required For:

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

Lower Threshold for Admission:

• Presentation in afternoon/evening 1
• Recent nocturnal symptoms 1
• Previous severe attacks or recent hospital admission 1, 2
• Poor adherence or concerning social circumstances 1

Discharge Criteria

Patients may be discharged when ALL of the following are met:

• PEF ≥70% of predicted or personal best 1, 2
• Symptoms minimal or absent 1, 2
• Oxygen saturation stable on room air 1, 2
• Stable for 30-60 minutes after last bronchodilator dose 1, 2

At Discharge, Ensure:

• Continue oral corticosteroids for 5-10 days (no taper needed) 1, 2
• Initiate or continue inhaled corticosteroids 1, 2
• Provide written asthma action plan 1
• Verify correct inhaler technique 1, 3
• Arrange follow-up within 1 week with primary care 1

Monitoring Parameters

• Continuous oxygen saturation monitoring until clear response to therapy 1, 2
• PEF or FEV₁ measurement before and after treatments 1, 2
• Vital signs and symptoms assessed every 15-30 minutes initially 1, 2
• Arterial blood gas if life-threatening features or poor response to treatment 1