Chronic Asthma in children
Chronic asthma in children is a long-term condition characterised by chronic inflammation of the airways, leading to hyper-responsiveness and reversible airflow obstruction. The UK’s management guidelines, notably from the British Thoracic Society (BTS) and the Scottish Intercollegiate Guidelines Network (SIGN), emphasise a stepwise approach to treatment and a strong focus on self-management and education.
Pathophysiology and Aetiology
Asthma is linked to atopy, a genetic predisposition to develop allergic diseases. The immune response in asthma has two phases:
Immediate Response: Triggered by allergens, leading to the release of inflammatory mediators (e.g., histamine, leukotrienes), causing bronchospasm and increased mucus secretion. This is the part that responds well to short-acting bronchodilators.
Late-Phase Response: Characterised by a cellular infiltrate that causes ongoing inflammation, oedema, and further bronchospasm, which can persist for hours or days. This phase is targeted by inhaled corticosteroids.
Common triggers for asthma exacerbations include viral infections (the most frequent cause), allergens (pollen, dust mites), irritants (cigarette smoke), exercise, and certain medications (NSAIDs).
Clinical Assessment
A comprehensive assessment is key to both diagnosis and ongoing management.
History: A detailed history is essential. Enquire about:
Symptoms: Recurrent wheezing, cough (especially at night or with exercise), and shortness of breath.
Triggers: Identify specific triggers such as infections, allergens, or exercise.
Atopy: Ask about a personal or family history of atopic conditions like eczema, hay fever, and food allergies.
Previous Episodes: Document the frequency and severity of past exacerbations, including any previous hospital admissions, or need for nebulisers or intensive care.
Current Management: Review the patient’s current treatment plan, including the use of both reliever (e.g., salbutamol) and preventer (e.g., inhaled corticosteroids) inhalers, as well as inhaler technique.
Examination: The child may have a normal chest examination if they are asymptomatic. During an exacerbation, look for:
Signs of increased work of breathing: Nasal flaring, intercostal/subcostal recession, and tracheal tug.
Auscultation: Listen for a prolonged expiratory phase and diffuse wheezing. A “silent chest” is a critical sign of severe airway obstruction and requires immediate action.
Diagnosis and Investigations
A diagnosis of asthma is primarily clinical, but objective tests can support it.
Spirometry: This is the gold standard for children over 5 years old. It shows an obstructive pattern with a reduced FEV1 and FEV1/FVC ratio. A key finding is reversibility, defined as an increase in FEV1 by 12% following a bronchodilator.
Peak Expiratory Flow Rate (PEFR): Daily PEFR monitoring can show a diurnal variation (20%), which supports a diagnosis of asthma and helps assess control.
Fractional Exhaled Nitric Oxide (FeNO): A higher-than-normal FeNO level indicates eosinophilic airway inflammation, which can support the diagnosis and help monitor adherence to inhaled corticosteroid therapy.
Chest X-ray: Not routinely indicated but may be used to rule out other diagnoses, such as a foreign body, or to identify complications like a pneumothorax.
Management of Chronic Asthma in Children:
The management of chronic asthma in children in the UK has evolved. Current guidelines, notably from the British Thoracic Society (BTS) and the Scottish Intercollegiate Guidelines Network (SIGN), now promote a MART (Maintenance and Reliever Therapy) approach for a significant proportion of children with asthma. This strategy aims to simplify treatment, improve adherence, and reduce the risk of severe exacerbations.
Key Principles of MART
The MART strategy is a significant shift from the traditional “preventer and reliever” approach. It uses a single inhaler that contains both a low-dose inhaled corticosteroid (ICS) and a fast-acting, long-acting beta-2 agonist (LABA), such as formoterol.
Single Inhaler: Children on MART use the same inhaler for both their daily preventer dose and for reliever medication when they have symptoms.
Benefits:
Simplicity: Reduces the need for multiple inhalers, improving adherence.
Effective: Ensures that a dose of a corticosteroid is taken with every dose of a reliever, targeting the underlying inflammation and not just the bronchospasm.
Reduced Exacerbations: Clinical trials have shown that MART significantly reduces the risk of severe asthma exacerbations compared to traditional regimens.
UK Stepwise Approach
The BTS/SIGN guidelines have integrated MART into the stepwise management of asthma.
Step 1: Mild Intermittent Asthma
A short-acting beta-2 agonist (SABA), such as salbutamol, is used as a reliever on an as-needed basis.
Step 2: Low-Dose Inhaled Steroids
If the child needs their SABA more than twice a month, or has had a severe exacerbation, a low-dose inhaled corticosteroid (ICS) is started as a regular preventer.
Step 3: MART as First-Line Add-On
If symptoms are not controlled on a low-dose ICS alone, MART becomes the preferred add-on therapy. This involves switching the child to a single inhaler containing a low-dose ICS and formoterol. The child takes a dose twice daily for maintenance and an extra puff as a reliever when they have symptoms.
Step 4: Medium-Dose MART
If symptoms persist, the maintenance dose of the MART inhaler is increased.
Step 5: High-Dose MART and Specialist Referral
For persistent poor control, the dose of the MART inhaler is increased to a high dose. At this point, the child requires a referral to a paediatric respiratory specialist to consider other therapies, such as leukotriene receptor antagonists (LTRA), or to investigate for poor adherence or other diagnoses.
Key Principles and Modern Terminology
Asthma Action Plan: Every child with asthma should have a written action plan that is tailored to them. It should clearly state their baseline therapy and what to do if their symptoms worsen.
Inhaler Technique: Poor inhaler technique is a major reason for treatment failure. All clinicians should regularly check and correct inhaler technique. The use of a spacer device is a fundamental part of good practice, especially in younger children.
Risk Stratification: The focus is no longer just on symptom control, but also on identifying risk factors for future severe exacerbations, such as previous hospital admissions or poor adherence.
Empowering the Patient: Modern management aims to empower children and families to be active participants in their care, recognising triggers and managing their condition effectively.