Key Facts

Childhood asthma is extremely common and carries significant morbidity. Good asthma control is achievable for most children with appropriate education, inhaler technique, and stepwise pharmacological management.

Epidemiology

Asthma affects approximately 1.1 million children in the UK. Prevalence peaks at age 5-9. Boys are more commonly affected before puberty; girls after puberty. Approximately 25,000 children are hospitalised for asthma annually. UK childhood asthma mortality has improved but remains higher than comparable European countries.

Aetiology

• Genetic: Strong genetic component; polygenic; family history of atopy/asthma
• Environmental: Allergens (house dust mite, pets, mould), viral infections, air pollution, tobacco smoke exposure, exercise, cold air
• Atopic march: Eczema → food allergy → asthma → allergic rhinitis

Pathophysiology

Asthma is a chronic inflammatory airway disease characterised by:

• Airway inflammation: Eosinophilic (type 2), Th2-mediated; mast cell activation
• Bronchial hyperreactivity: Exaggerated bronchoconstriction to triggers
• Reversible airflow obstruction: Smooth muscle contraction, mucosal oedema, mucus hypersecretion
• Airway remodelling: Chronic inflammation → subepithelial fibrosis, smooth muscle hypertrophy (can become irreversible)

Typical Features

• Recurrent episodic wheeze (expiratory)
• Cough (especially nocturnal, exercise-induced)
• Breathlessness, chest tightness
• Symptom variability — worse at night/early morning, with exercise, in cold air, with viral infections
• Symptom reversibility with bronchodilators
• Atopic history (eczema, allergic rhinitis, food allergy) or family history

Severity Assessment (Acute Exacerbation)

• Moderate: SpO2 ≥92%, able to talk, PEF >50%
• Severe: SpO2 <92%, too breathless to talk/feed, PEF 33-50%, HR >140 (<5yr) or >125 (>5yr)
• Life-threatening: SpO2 <92%, silent chest, cyanosis, exhaustion, confusion, PEF <33%

Red Flags

• Previous PICU admission — high-risk patient
• Frequent oral steroid courses (>2/year) — poorly controlled; step up treatment
• Night-time waking with wheeze/cough — indicates inadequate control
• Not growing — consider alternate diagnosis or steroid side effects

Bedside

• PEF diary: Home PEF monitoring — >20% variability supports asthma diagnosis
• SpO2: In acute exacerbation

Objective Tests (>5 years — NICE NG80)

• Spirometry: FEV1/FVC ratio; obstructive pattern (ratio <0.7 or below LLN)
• Bronchodilator reversibility: ≥12% AND 200mL improvement in FEV1 post-SABA
• FeNO: ≥35ppb in children supports eosinophilic airway inflammation
• PEF variability: >20% on twice-daily readings over 2-4 weeks

Bloods

• Total IgE, specific IgE/skin prick tests: Identify atopic triggers
• FBC: Eosinophilia supports atopic inflammation

Imaging

• CXR: If diagnostic uncertainty (exclude foreign body, infection, structural abnormality)

Special Tests

• Challenge tests: Exercise, methacholine — specialist use
• Sweat test: If CF suspected

Non-pharmacological

• Written personalised asthma action plan: Every child — recognise worsening, when to step up, when to seek help
• Inhaler technique: Review at every visit; spacer device (Volumatic/AeroChamber) mandatory for MDI
• Trigger avoidance: Tobacco smoke, allergens; weight management
• Annual influenza vaccination: All children with asthma

Pharmacological (BTS/SIGN Stepwise — Children 5-12)

• Step 1: SABA PRN (salbutamol 100mcg 2 puffs via spacer)
• Step 2: Add low-dose ICS (beclometasone 100-200mcg/day or equivalent)
• Step 3: Add LABA (salmeterol) or LTRA (montelukast 5mg OD); review and stop LTRA if no benefit at 4-8 weeks
• Step 4: Increase ICS to medium dose (200-400mcg beclometasone equivalent)
• Step 5: Refer to specialist; high-dose ICS, oral steroids, biologic therapy (omalizumab, mepolizumab for severe eosinophilic asthma)

Children <5:

• SABA PRN → low-dose ICS → add LTRA → specialist referral

Acute Exacerbation

• Salbutamol 10 puffs via spacer (2 puffs at a time); repeat every 20 min if needed
• Oxygen: If SpO2 <94%
• Prednisolone: 1-2mg/kg (max 40mg) for 3 days
• Nebulised salbutamol + ipratropium: If severe/life-threatening
• IV MgSO4, IV aminophylline: Life-threatening asthma

Referral Criteria

• Diagnostic uncertainty — respiratory paediatrician
• Poorly controlled despite Step 3-4 — specialist review
• Previous PICU admission — specialist follow-up
• Considering biologic therapy — tertiary severe asthma centre

• ~50% of childhood asthma resolves by adulthood (especially mild, non-atopic)
• Persistent asthma: More likely if severe, atopic, female, early onset with atopy
• Well-controlled asthma: Children should have normal lung function, normal activity, and no limitations
• Mortality: ~10-20 children die from asthma each year in the UK — most deaths are preventable with better management
• NRAD findings: Most childhood asthma deaths involved modifiable factors (poor adherence, no action plan, under-treatment)

BTS/SIGN Stepwise Management (Children 5-12)

ICS Dose Equivalents (Children)