What nebulized levosalbutamol (R‑albuterol) dose should be given to a child with acute asthma or wheeze, including the initial burst dosing and subsequent PRN dosing, and what maintenance dose is appropriate for children aged 4‑11 years?

Nebulized Levosalbutamol Dosing in Pediatric Acute Asthma

For children with acute asthma or wheeze, give levosalbutamol 0.075 mg/kg (minimum 1.25 mg) via nebulizer every 20 minutes for three doses during the first hour, then continue 0.075–0.15 mg/kg every 1–4 hours as needed based on clinical response. 1, 2

Initial Burst Dosing (First Hour)

• Weight-based dosing: Administer 0.075 mg/kg per dose with a minimum of 1.25 mg regardless of weight 2
• Frequency: Repeat every 20 minutes for three consecutive doses during the intensive phase 1, 2
• Dilution: Mix the levosalbutamol dose in 2–3 mL of normal saline for adequate nebulization 1
• Gas source: Use oxygen at 6–8 L/min flow rate as the driving gas to maintain SpO₂ > 92% 1, 2

Practical Dosing by Weight

• Children < 20 kg: Use 1.25 mg per dose (the minimum dose) 1
• Children ≥ 20 kg: Calculate 0.075 mg/kg, typically resulting in 1.25 mg for most pediatric patients 2
• Maximum single dose: Generally 1.25 mg for children, though up to 2.5 mg may be used in adolescents approaching adult weight 1, 2

Subsequent PRN Dosing (After First Hour)

• Dosing range: 0.075–0.15 mg/kg every 1–4 hours as needed 1, 2
• Practical approach: Most children receive 1.25 mg every 1–4 hours depending on severity and response 2
• Reassessment timing: Evaluate clinical status 15–30 minutes after each dose to guide frequency 2

Response-Guided Frequency

• Good response (PEF > 75% predicted, minimal symptoms): Continue every 4 hours as needed 2
• Incomplete response (PEF 50–75% predicted, persistent symptoms): Continue every 1–2 hours 2
• Poor response (PEF < 50% predicted): Increase to every 15–30 minutes or consider continuous nebulization 1, 2

Maintenance Dosing for Children Aged 4–11 Years

• Chronic maintenance: Levosalbutamol is not recommended for scheduled maintenance therapy; use only as needed for symptom relief 1
• Home PRN dosing: 1.25 mg as needed for breakthrough symptoms, typically not more than every 4 hours 1
• Maximum daily dose: Do not exceed 40 mg/day during acute exacerbations (equivalent to approximately 32 doses of 1.25 mg, which is impractical and signals need for escalation) 1

Dose Equivalence to Racemic Albuterol

• Levosalbutamol is given at approximately half the milligram dose of racemic albuterol to achieve comparable efficacy 1, 2
• Example: 1.25 mg levosalbutamol ≈ 2.5 mg racemic albuterol 1
• This equivalence applies because levosalbutamol contains only the active R-enantiomer, whereas racemic albuterol is 50% active R-isomer and 50% inactive S-isomer 1

Alternative Delivery: MDI with Spacer

• Dose: 4–8 puffs (each puff typically 45 mcg levosalbutamol) every 20 minutes for three doses, then every 1–4 hours as needed 1
• Device requirement: Always use a spacer/holding chamber; for children < 4 years, add a face mask 1
• Equivalence: MDI with spacer is equally effective as nebulization and may result in lower admission rates with fewer cardiovascular side effects 2

Adjunctive Therapy in Moderate-to-Severe Exacerbations

• Ipratropium bromide: Add 0.25–0.5 mg (250–500 mcg) to the nebulizer for the first three doses if moderate-to-severe exacerbation (PEF < 50% predicted, respiratory rate > 50/min, heart rate > 140/min) 1, 3, 2
• Mixing: Ipratropium can be mixed with levosalbutamol in the same nebulizer chamber 1, 3
• Continuation: After initial three doses, continue ipratropium every 6 hours until clinical improvement begins 3, 2

Systemic Corticosteroids (Mandatory)

• Dose: Prednisolone 1–2 mg/kg orally (maximum 40–60 mg) immediately at presentation 2
• Duration: Continue for 3–5 days without taper if course < 10 days 2
• Alternative: If vomiting or critically ill, give IV hydrocortisone 100 mg every 6 hours 2
• Critical pitfall: Do not delay systemic corticosteroids while giving repeated bronchodilator doses alone—this is a common cause of treatment failure and preventable mortality 2

Safety Monitoring

• Cardiac: Monitor for tachycardia (expected but less pronounced with levosalbutamol than racemic albuterol) 1, 4
• Metabolic: Watch for tremor and hypokalemia, especially with high-frequency or high-dose therapy 1, 2
• Respiratory: Maintain continuous pulse oximetry with target SpO₂ > 92% 2
• Reassessment: Measure respiratory rate, heart rate, SpO₂, and PEF (if age ≥ 5 years) after each treatment 2

Evidence for Levosalbutamol vs. Racemic Albuterol

• Efficacy: Small studies show levosalbutamol yields modestly better SpO₂, PEFR, and asthma scores compared to racemic albuterol 2, 4
• Safety: Levosalbutamol causes less tachycardia and hypokalemia than racemic albuterol at equivalent bronchodilator doses 2, 4, 5
• Guideline status: Major international guidelines (British Thoracic Society, American Academy of Pediatrics) recommend racemic albuterol as the standard, but explicitly state levosalbutamol may be used at half the milligram dose 1, 2
• Clinical context: The evidence for levosalbutamol is limited and not yet incorporated into most major guidelines, but it is a reasonable alternative when available, particularly in children with significant tachycardia on racemic albuterol 2, 4

Escalation for Refractory Cases

• Continuous nebulization: If no improvement after initial three doses, switch to 0.5 mg/kg/hour (maximum 10–15 mg/hour) 1
• For levosalbutamol: This translates to approximately 0.25 mg/kg/hour (half the racemic dose) 1
• IV therapy: For life-threatening deterioration, consider IV aminophylline 5 mg/kg over 20 minutes followed by 1 mg/kg/hour infusion (do not give loading dose if already on oral theophylline) 2
• ICU transfer: Arrange immediate transfer for worsening PEF despite treatment, increasing exhaustion, persistent hypoxia (SpO₂ < 92%), hypercapnia, altered consciousness, or respiratory arrest 2

Hospital Admission Criteria

• Immediate admission required for: Any life-threatening feature (PEF < 33% predicted, silent chest, cyanosis, altered consciousness), persistent severe attack after initial therapy, PEF < 50% after 1–2 hours of intensive treatment, or inability of caregivers to manage at home 2
• Lower threshold for admission: Evening presentations, recent nocturnal symptoms, prior severe attacks, or poor social support 2

Discharge Planning

• Criteria: Stable on medication for ≥ 24 hours, verified inhaler technique, PEF > 75% predicted, diurnal PEF variability < 25%, minimal symptoms 2
• Home regimen: Continue inhaled corticosteroids alongside PRN levosalbutamol (1.25 mg as needed, typically not more than every 4 hours) 1, 2
• Corticosteroid completion: Prescribe prednisolone 1–2 mg/kg daily to complete a total 3–5-day course 2
• Follow-up: Arrange GP visit within 1 week and respiratory clinic review within 4 weeks 2

Common Pitfalls to Avoid

• Underdosing: Do not use less than the minimum 1.25 mg dose in young children—weight-based dosing ensures adequate bronchodilation 1, 2
• Overdosing: Do not exceed 0.15 mg/kg per dose or give more frequently than every 15 minutes without considering continuous nebulization 1, 2
• Sedatives: Absolutely contraindicated in acute pediatric asthma—they can depress respiratory function 2
• Delaying steroids: Always give systemic corticosteroids immediately; do not wait to see if bronchodilators alone will work 2
• Ignoring objective measures: Do not rely solely on subjective assessment—obtain PEF and SpO₂ measurements 2