Acute Asthma Exacerbation in Children
Asthma is a common long-term condition in the UK. Acute severe asthma is a medical emergency that requires immediate recognition and structured management to prevent a life-threatening episode. UK guidelines from NICE, the British Thoracic Society (BTS), and the Scottish Intercollegiate Guidelines Network (SIGN) provide a clear, step-wise approach.
Clinical Assessment
The assessment of a child with acute asthma should be rapid and systematic.
History:
Pre-morbid Function: Enquire about the child’s usual asthma control, daily medications, and use of a spacer.
Previous Admissions: Ask about any previous hospitalisations, especially those that required high dependency unit (HDU) or paediatric intensive care unit (PICU) admission.
Trigger Factors: Identify potential triggers for the current attack, such as a viral upper respiratory tract infection (URTI), allergens, or cold air.
Rapid Assessment:
Severity: Classify the severity of the attack using a combination of clinical signs. This determines the urgency and intensity of treatment.
Differential Diagnosis: Always consider other causes of breathlessness, such as a foreign body, bronchiolitis (especially in infants), or pneumonia.
Objective Measures:
Oxygen Saturation (SaO2): This is a critical vital sign.
Peak Expiratory Flow Rate (PEFR): A useful measure in children over 5 years who are able to cooperate. It should be compared to their best or predicted PEFR.
Management
The management of acute asthma follows a step-wise approach based on the severity.
Initial Management for all Severities
Administer Oxygen: Provide oxygen via a mask to maintain an oxygen saturation (SaO2) >94%.
First-line Bronchodilator: Administer salbutamol via a metered-dose inhaler (MDI) and spacer. The use of a spacer is as effective as a nebuliser and can be used in almost all cases, even in severe attacks.
Moderate to Severe Episode
Salbutamol: Give 2-4 puffs of salbutamol via MDI and spacer every 20 minutes for the first hour. If not improving, give back-to-back doses.
Ipratropium Bromide: Add ipratropium bromide (via MDI + spacer or nebulised) every 20 minutes for the first hour.
Corticosteroids: Give oral prednisolone or dexamethasone early in the management. Dexamethasone is increasingly used in the UK due to its longer half-life, which can lead to better compliance.
Admission: Children with severe asthma or those not responding to initial treatment should be admitted to hospital for continued monitoring and treatment.
Life-Threatening Episode
Immediate Senior Review: Call for senior help and consider transferring the child to a high-dependency or resuscitation area.
Continuous Nebulisers: If the child is not responding, switch to continuous nebulised salbutamol.
Intravenous (IV) Therapy:
IV Magnesium Sulphate: This is a second-line therapy for severe asthma and should be administered if there is no immediate response to initial bronchodilators. It helps relax the smooth muscles in the airways.
IV Hydrocortisone: If oral steroids cannot be administered or are ineffective, IV hydrocortisone is an alternative.
IV Salbutamol: A continuous intravenous infusion of salbutamol should be considered for children with life-threatening asthma who are not responding to nebulised therapy.
Specialist Consultation: Contact the on-call anaesthetics and PICU teams for input, as intubation and mechanical ventilation may be required.
Pitfalls and Nuances
“Too Quiet to Wheeze”: A silent chest can be an ominous sign, indicating that the child is too exhausted to move enough air to produce a wheeze. This is an indicator of life-threatening asthma.
Hypercapnia and Respiratory Exhaustion: A normal or rising PaCO2 on a blood gas is a critical red flag, as it indicates impending respiratory failure and a need for ventilatory support.
Discharge Planning: At discharge, a written Asthma Action Plan must be provided. It should include guidance on when to escalate care, proper inhaler technique with a spacer, and a follow-up appointment within 48 hours.