What is the appropriate salbutamol nebuliser dose and dosing schedule for children (including infants) with an acute asthma or wheeze exacerbation based on weight?

Salbutamol Nebulizer Dosing for Pediatric Acute Asthma and Wheeze

For children with acute asthma or wheeze exacerbations, administer salbutamol 2.5 mg via oxygen-driven nebulizer for children under 15 kg or under 2 years of age, and 5 mg for children 15 kg and above, repeated every 20 minutes for three doses in the first hour, then every 1-4 hours as needed based on clinical response. 1, 2

Weight-Based Dosing Algorithm

Initial Intensive Phase (First Hour)

• Children < 15 kg or ≤ 2 years: Give salbutamol 2.5 mg via oxygen-driven nebulizer every 20 minutes for three consecutive doses 1, 2
• Children ≥ 15 kg or > 2 years: Give salbutamol 5 mg via oxygen-driven nebulizer every 20 minutes for three consecutive doses 1, 2
• Reassess respiratory status, peak expiratory flow (if age ≥ 5 years), heart rate, and oxygen saturation 15-30 minutes after starting treatment 1, 2

Subsequent Maintenance Dosing (After First Hour)

Response-guided approach:

• Good response (PEF > 75% predicted, minimal symptoms): Continue usual maintenance therapy with bronchodilators as needed, typically every 4-6 hours 1
• Incomplete response (PEF 50-75% predicted, persistent symptoms): Continue salbutamol every 4 hours, maintain high-flow oxygen, continue systemic corticosteroids 1
• Poor response (PEF < 50% predicted or ongoing severe features): Increase salbutamol frequency to every 15-30 minutes or consider continuous nebulization 1, 2

Alternative Delivery Method

• Metered-dose inhaler (MDI) with large-volume spacer is equally effective: Give 4-8 puffs (400-800 mcg) every 20 minutes for three doses, then every 1-4 hours as needed 1, 3
• MDI with spacer may result in lower admission rates and fewer cardiovascular side effects compared to nebulization 1

Essential Concurrent Therapies

• Oxygen: Deliver high-flow oxygen (40-60%) via face mask to maintain SpO₂ > 92% 1, 2
• Systemic corticosteroids: Administer prednisolone 1-2 mg/kg orally (maximum 40-60 mg) immediately; if vomiting or critically ill, give IV hydrocortisone 100 mg every 6 hours 1, 2
• Ipratropium bromide: Add 100-250 mcg to each nebulizer treatment for moderate-to-severe exacerbations; repeat every 6 hours until improvement begins 1, 2

Severity Assessment to Guide Dosing Frequency

Severe Exacerbation Features:

• Too breathless to talk or feed 1, 2
• Respiratory rate > 50 breaths/min 1, 2
• Heart rate > 140 beats/min 1, 2
• Peak expiratory flow < 50% predicted 1, 2
• Use of accessory muscles 1, 2

Life-Threatening Features (Requiring ICU Transfer):

• PEF < 33% predicted 1
• Silent chest, cyanosis, poor respiratory effort 1, 2
• Altered consciousness or exhaustion 1, 2
• SpO₂ < 92% despite supplemental oxygen 1, 2

Monitoring Requirements

• Measure peak expiratory flow before and after each β-agonist dose at least four times daily (in children ≥ 5 years) 1
• Continuous pulse oximetry targeting SpO₂ > 92% 1, 2
• Monitor for expected tachycardia; bradycardia is an ominous sign requiring immediate escalation 1

Critical Pitfalls to Avoid

• Do not delay systemic corticosteroids while giving repeated salbutamol doses alone—this is a common cause of treatment failure and preventable mortality 1
• Never use sedatives in acute pediatric asthma; they are absolutely contraindicated and can be fatal 1
• Do not rely solely on clinical impression; obtain objective measurements (PEF, SpO₂) to assess severity 1, 2
• Recognize that salbutamol may be ineffective in wheezy infants under 1 year without a clear asthma diagnosis; consider alternative diagnoses if no response after appropriate dosing 4

Hospital Admission Criteria

• Any life-threatening feature present 1, 2
• Persistent severe attack after initial therapy 1, 2
• PEF < 50% after 1-2 hours of intensive treatment 1
• Inability of caregivers to manage at home 1
• Evening presentations, recent nocturnal symptoms, or prior severe attacks warrant lower threshold for admission 1

Discharge Planning (When Stable)

• Patient must be stable on discharge medications for ≥ 24 hours 1, 2
• PEF > 75% predicted with diurnal variability < 25% 1, 2
• Verified correct inhaler technique 1, 2
• Provide written asthma action plan and peak flow meter 1, 2
• Arrange GP follow-up within 1 week and respiratory specialist within 4 weeks 1, 2
• Discharge with salbutamol as needed rather than fixed-dose weaning regimens; families can safely manage with much lower doses when given proper guidance on 4-hourly assessments 5