Paediatric Asthma Summary

Differential Diagnosis

  • Bronchiolitis
  • Viral-induced wheeze
  • Pneumonia
  • Aspiration
  • Congenital anomalies

Severity Classification

  • Moderate: Sentences, SpO₂ ≥92%, PEF ≥50%
  • Severe: Can't talk/feed, SpO₂ <92%, PEF 33-50%
  • Life-threatening: Exhaustion, silent chest, confusion

First-line Treatment

  • Oxygen: High-flow to SpO₂ 94-98%
  • β₂-agonist: pMDI+spacer or nebulised
  • Steroids: Oral prednisolone early
  • Ipratropium: Add if refractory

Second-line IV Treatment

  • Magnesium sulphate (40mg/kg)
  • IV salbutamol (15μg/kg bolus)
  • IV aminophylline (5mg/kg loading)
  • IV hydrocortisone if unable to take oral

Investigations

  • Pulse oximetry (SpO₂ <92% → inpatient)
  • PEF (<50% predicted → prolonged attack)
  • CXR only if complications suspected
  • Blood gases if life-threatening

Drug Doses

  • Prednisolone: 10mg (<2y), 20mg (2-5y), 30-40mg (>5y)
  • Salbutamol: 2.5-5mg nebulised q20-30min
  • Ipratropium: 250μg with nebulised β₂ agonist

Discharge Criteria

  • Stable on 3-4 hourly bronchodilators
  • PEF/FEV₁ >75% predicted
  • SpO₂ >94% in air
  • Written asthma action plan

Paediatric Acute Asthma

Assessment and management of acute asthma in children

Introduction

The assessment of acute asthma in children under five can be difficult. Intermittent wheezing attacks are usually triggered by viral infection and the response to asthma medication may be inconsistent. Prematurity and low birth weight are risk factors for recurrent wheezing.

Differential Diagnosis

  • Aspiration pneumonia
  • Pneumonia
  • Bronchiolitis
  • Viral-induced wheeze
  • Tracheomalacia
  • Congenital anomalies
  • Cystic fibrosis

Viral-Induced Wheeze

Viral-induced wheeze is a condition which largely affects children between the ages of 6 months and 5 years. Wheeze is associated with respiratory tract infection and in the majority of children the tendency to wheeze remits by 6 years of age.

Note: These guidelines are intended for children who are thought to have acute wheeze related to underlying asthma and should be used with caution in younger children who do not yet have a confirmed diagnosis of asthma, particularly those under two years of age. The guidelines are not intended for children under one year of age unless directed by a respiratory paediatrician.

Initial Assessment

Clinical Features

  • Heart rate
  • Respiratory rate and degree of breathlessness
  • Use of accessory muscles of respiration
  • Amount of wheezing
  • Degree of agitation or confusion

Investigations

  • Pulse oximetry: Consider intensive inpatient treatment if SpO₂ < 92% in air after initial bronchodilator treatment
  • Peak expiratory flow: <50% predicted PEF (best of three) with poor improvement suggests prolonged attack
  • Chest x-ray: Only if subcutaneous emphysema, pneumothorax, lobar collapse or life-threatening asthma not responding
  • Blood gases: Consider if life-threatening features not responding (venous PaCO₂ <6 kPa excludes hypercapnia)

Classification of Severity

Severity Criteria
Moderate
  • Able to talk in sentences
  • SpO₂ ≥ 92%
  • PEF ≥ 50% of best or predicted
  • Heart rate ≤140/min (1-5y) or ≤125/min (>5y)
  • Respiratory rate ≤40/min (1-5y) or ≤30/min (>5y)
Severe
  • Can't complete sentences/too breathless to talk/feed
  • SpO₂ < 92%
  • PEF 33-50% of best or predicted
  • Heart rate >140/min (1-5y) or >125/min (>5y)
  • Respiratory rate >40/min (1-5y) or >30/min (>5y)
Life-threatening
  • Any of: exhaustion, hypotension, cyanosis, silent chest, poor respiratory effort, confusion
  • PEF <33% of best or predicted
  • SpO₂ <92%

Note: If a patient has signs and symptoms across categories, always treat according to their most severe features.

Management

Oxygen Therapy

Children with life-threatening asthma or SpO₂ <94% should receive high-flow oxygen via tight fitting face mask or nasal cannula to achieve SpO₂ 94-98%.

β₂-agonist Bronchodilators

  • First line treatment for acute asthma
  • pMDI with spacer preferred for mild/moderate asthma (face mask needed for <3y)
  • Severe cases: nebulised salbutamol 2.5-5mg every 20-30 minutes (oxygen-driven)

Ipratropium Bromide

Add ipratropium bromide (250μg/dose mixed with nebulised β₂-agonist) if symptoms refractory to initial treatment, repeated every 20-30 minutes.

Steroid Therapy

  • Oral prednisolone early in treatment
  • Dose by age: 10mg (<2y), 20mg (2-5y), 30-40mg (>5y)
  • IV hydrocortisone (4mg/kg) if unable to retain oral medication

Second Line Treatments

  • IV magnesium sulphate (40mg/kg) as first-line IV treatment
  • IV salbutamol bolus (15μg/kg over 10 mins) for severe attacks unresponsive to inhaled therapy
  • IV aminophylline (5mg/kg loading then 1mg/kg/hr) for severe/life-threatening asthma unresponsive to other treatments

Important Notes

  • β₂ bronchodilator via spacer given one puff at a time, inhaled separately using tidal breathing
  • Give another puff every 60 seconds up to maximum of 10 puffs according to response
  • Do not give antibiotics routinely

Drug Doses

Drug Dose
Oxygen High-flow to achieve SpO₂ 94-98%
Inhaled salbutamol
  • pMDI + spacer: 1 puff every 30-60s (max 10 puffs)
  • Nebulised: 2.5-5mg every 20-30 mins (severe asthma)
Ipratropium bromide 250μg/dose with nebulised β₂ agonist, every 20-30 mins
Oral prednisolone
  • <2y: 10mg
  • 2-5y: 20mg
  • >5y: 30-40mg
Nebulised magnesium sulphate
  • Consider adding 150 mg to each nebulised salbutamol and ipratropium in the first hour in children with a short duration of acute severe asthma symptoms presenting with an Sp02 < 92%
IV hydrocortisone 4mg/kg every 4 hours (if unable to retain oral medication)
IV salbutamol 15μg/kg over 10 mins, then infusion 1-5μg/kg/min if needed
IV aminophylline 5mg/kg loading over 20 mins, then 1mg/kg/hr infusion
IV magnesium sulphate Consider the addition of 40 mg/kg/day as first-line intravenous treatment in children who respond poorly to first-line treatments

Discharge Planning

Discharge Criteria

  • Stable on 3-4 hourly inhaled bronchodilators
  • PEF/FEV₁ >75% of best or predicted
  • SpO₂ >94% in air

Follow Up

Discharge Medications
  • Continue β₂ bronchodilator 4 hourly as needed
  • Continue prednisolone until recovery (minimum 3-5 days)
  • Provide written asthma action plan
  • Review regular treatment and inhaler technique