Acute Asthma Exacerbation In Children

An acute asthma exacerbation is a sudden or progressive worsening of wheeze, cough, breathlessness and expiratory airflow limitation requiring escalation of treatment. Viral respiratory infection is the commonest trigger in children, but allergens, smoke, exercise, poor controller adherence and incorrect inhaler technique are frequent contributors.

Severity is determined by the child's overall respiratory state, not wheeze intensity alone. A quiet or silent chest in a distressed child suggests critically reduced airflow and impending respiratory failure.

Mild to moderate exacerbations cause:

• Wheeze
• Cough
• Tachypnoea
• Prolonged expiration
• Increased work of breathing
• Reduced exercise or feeding tolerance

Severe or life threatening features include:

• SpO₂ below 90%
• Central cyanosis
• Inability to speak, drink or breastfeed normally
• Severe accessory muscle use
• Agitation followed by drowsiness
• Exhaustion
• Markedly reduced air entry
• Silent chest
• Bradycardia or hypotension
• Altered consciousness

A rising PaCO₂ in a child with severe asthma is ominous. Early attacks usually produce hypocapnia. Normalizing or rising carbon dioxide with persistent respiratory distress suggests fatigue and impending ventilatory failure.

Diagnosis is clinical.

Immediately assess:

• Respiratory rate
• Heart rate
• Work of breathing
• Ability to speak or feed
• Air entry
• Wheeze
• Conscious level
• Oxygen saturation

Peak expiratory flow can help quantify severity in cooperative older children, but inability to perform it should never delay treatment.

Chest radiography is not routine. Obtain it when pneumothorax, focal pneumonia, foreign body aspiration or another diagnosis is suspected.

Blood gas is reserved for severe disease, exhaustion, deteriorating consciousness or suspected ventilatory failure.

Give inhaled salbutamol immediately.

For younger children:

• Salbutamol 4 to 6 puffs of 100 micrograms via pMDI and spacer, one puff at a time with several tidal breaths after each puff

or

• Salbutamol 2.5 mg nebulised

Repeat every 20 minutes for the first hour in moderate or severe exacerbations, then reassess.

Give oxygen for significant hypoxaemia.

Add ipratropium bromide 250 micrograms nebulised every 20 minutes for 3 doses in severe exacerbations.

Give systemic corticosteroid early:

• Prednisolone 1 to 2 mg/kg PO once daily for 3 to 5 days

Maximum:

• 20 mg/day if younger than 2 years
• 30 mg/day at 2 to 5 years

For older children, usual maximum dosing may extend to 40 to 50 mg/day depending on protocol.

In severe disease with poor response:

• Magnesium sulfate 40 to 50 mg/kg IV over 20 minutes, maximum 2 g

Escalate urgently for silent chest, exhaustion, worsening hypoxaemia, altered consciousness or rising PaCO₂.

Do not routinely give antibiotics unless bacterial infection is independently suspected.