What is the appropriate nebulised salbutamol dose (mg/kg) and dosing schedule for an infant with acute bronchospasm?

Pediatric Salbutamol Nebulization Dosing for Infants

For infants with acute bronchospasm, administer 0.15 mg/kg of nebulized salbutamol with a mandatory minimum dose of 2.5 mg, regardless of calculated weight-based dose. 1

Weight-Based Calculation for Infants

• Calculate the dose as 0.15 mg/kg of body weight, but always default to the 2.5 mg minimum if the calculated dose falls below this threshold 1, 2
• For a typical infant weighing 9-10 kg, the weight-based calculation yields only 1.35-1.5 mg, but you must administer the 2.5 mg minimum dose 1
• When using a 2 mg/5 mL formulation, deliver 6.25 mL per nebulization to provide the required 2.5 mg dose 1

Dosing Schedule for Acute Exacerbations

• Administer the initial three doses at 20-minute intervals during the first hour of treatment 1, 2
• After the first three doses, continue every 1-4 hours as needed, adjusting frequency based on respiratory rate, work of breathing, and oxygen saturation 1, 2
• The aggressive 20-minute interval during the first hour targets the period of maximal airway constriction and is critical for adequate bronchodilation 2

Nebulizer Setup and Delivery

• Use an oxygen-driven nebulizer with a flow rate of 6-8 L/min to optimize aerosol delivery and prevent hypoxemia during treatment 1, 2
• Dilute each dose to a minimum total volume of 3 mL with normal saline to ensure adequate aerosol generation 1, 2
• Provide continuous oxygen supplementation throughout nebulization to maintain peripheral oxygen saturation ≥90% 1

Adding Ipratropium for Moderate-to-Severe Distress

• For infants with moderate-to-severe respiratory distress (respiratory rate >50 breaths/min, use of accessory muscles, inability to feed, SpO₂ <90%), add ipratropium bromide 250 µg to each of the first three nebulized treatments 1, 2
• The British Thoracic Society recommends a half-dose of ipratropium (100-125 µg) in very young children, though the standard pediatric protocol employs 250 µg 1
• Do not continue ipratropium beyond the first three doses once the infant is hospitalized, as additional benefit has not been demonstrated 2

Preferred Alternative: MDI with Spacer

• A metered-dose inhaler (MDI) with spacer and face mask is the preferred first-line delivery method for infants when tolerated, offering comparable efficacy to nebulization while being more convenient and cost-effective 1
• If the infant tolerates the device, give 2 puffs (total 180 µg albuterol) via MDI-spacer-mask every 20 minutes for three doses; up to a cumulative total of 20 puffs may be administered in severe cases 1
• When an infant cannot tolerate a mask or spacer, nebulization remains the necessary delivery method 1

Systemic Corticosteroid Adjunct

• For persistent symptoms or moderate-to-severe exacerbations, add oral prednisolone 2 mg/kg/day for three days (maximum 40 mg/day) to improve outcomes 1, 2
• If oral administration is not feasible, use intravenous hydrocortisone 100 mg every six hours as an alternative 1

Critical Monitoring and Escalation

• Monitor for signs of impending respiratory failure: cyanosis, silent chest, poor respiratory effort, marked fatigue, reduced consciousness, or inability to maintain SpO₂ ≥90% despite supplemental oxygen 1, 2
• When maximal inhaled therapy (salbutamol ± ipratropium) fails to produce clinical improvement, initiate an aminophylline infusion with a loading dose of 5 mg/kg over 20 minutes followed by a maintenance infusion of 1 mg/kg/hour, and consider transfer to intensive care 1

Common Pitfalls to Avoid

• Never underdose in the acute setting—the 2.5 mg minimum is non-negotiable even when weight-based calculations suggest a lower dose 1
• Do not use compressed air or room air as the driving gas in hypoxic infants; always employ oxygen at 6-8 L/min unless there is specific concern for CO₂ retention 1
• Ensure a properly fitting face mask to maximize drug delivery efficiency in this age group 1
• Observe for β-adrenergic side effects such as tachycardia and tremor, though these are uncommon with inhaled salbutamol at standard doses 1, 3