Pediatric Asthma
Definition
Pediatric asthma is a chronic, reversible airway disease characterized by variable airflow limitation, bronchial hyper‑responsiveness (BHR), and airway inflammation. It presents with episodic wheeze, cough, chest tightness, and dyspnea, often triggered by allergens, viral infections, exercise, or cold air.
Epidemiology
- Global prevalence: 5–10 % of children worldwide; higher in urban, affluent societies.
- India: 4–7 % in school‑aged children; rising trend in urban slums and industrial areas.
- Age of onset: 2–6 years common; 80 % of cases diagnosed before age 12.
- Gender: Slight male preponderance before puberty; female predominance after puberty.
- Seasonality: Peaks in spring (allergens) and winter (viral infections).
- Socio‑economic factors: Lower socio‑economic status correlates with higher morbidity and mortality due to poor access to care.
Aetiology & Risk Factors
| Category | Key Factors |
|---|---|
| Genetic | Family history of atopy or asthma; HLA‑DR, IL‑4, IL‑13 polymorphisms. |
| Environmental | Tobacco smoke exposure, indoor pollutants (cooking fumes, mould), outdoor air pollution, viral infections (RSV, HRV). |
| Allergic | Sensitization to dust mites, pet dander, pollens, molds. |
| Non‑allergic | Obesity, gastro‑oesophageal reflux disease (GERD), viral infections, exercise. |
| Socio‑economic | Poor housing, overcrowding, limited access to healthcare. |
Pathophysiology
- Allergic sensitization → IgE‑mediated mast cell degranulation → release of histamine, leukotrienes, prostaglandins.
- Inflammatory cascade: Th2 cytokines (IL‑4, IL‑5, IL‑13) recruit eosinophils, basophils, and IgE‑producing B cells.
- Bronchial hyper‑responsiveness: Enhanced contractility of airway smooth muscle, increased mucus secretion, sub‑epithelial fibrosis.
- Airway remodeling: Chronic inflammation leads to smooth‑muscle hypertrophy, sub‑epithelial collagen deposition, and goblet‑cell hyperplasia.
- Trigger‑induced exacerbations: Viral infections cause epithelial damage, up‑regulation of adhesion molecules, and further cytokine release.
Clinical Features
- Typical symptoms: Intermittent wheeze (often inspiratory), cough (especially at night), chest tightness, shortness of breath.
- Patterns:
- Intermittent: Symptoms <2 days/week, normal FEV₁.
- Mild‑persistent: Symptoms >2 days/week, nighttime >1 day/month.
- Moderate‑persistent: Daily symptoms, nighttime >1 day/week.
- Severe‑persistent: Continuous symptoms, nighttime >3 days/week.
- Physical exam: Wheeze (bilateral, variable), prolonged expiratory phase, use of accessory muscles, cyanosis in severe attacks.
- Exacerbation triggers: Viral URIs, allergens, exercise, cold air, irritants, emotional stress.
- Comorbidities: Rhinitis, eczema, GERD, obesity, sleep‑disordered breathing.
Investigations
| Test | Indication | Key Findings |
|---|---|---|
| Spirometry | ≥5 yrs; baseline and post‑bronchodilator | FEV₁ <80 % predicted; >12 % improvement post‑bronchodilator indicates reversible obstruction. |
| Peak Expiratory Flow (PEF) | Daily monitoring | Variability >20 % indicates uncontrolled asthma. |
| FeNO | Assess eosinophilic inflammation | Elevated >25 ppb in children >6 yrs suggests Th2‑mediated inflammation. |
| Blood eosinophils | Baseline inflammation | >300 cells/µL correlates with steroid responsiveness. |
| Skin prick test / Specific IgE | Allergy work‑up | Positive to common aero‑allergens. |
| Chest X‑ray | Suspected infection or severe exacerbation | Usually normal; may show hyperinflation. |
| Exhaled breath condensate / sputum cytology | Research setting | Eosinophil counts >3 % predictive of exacerbations. |
Management (2024 Global Initiative for Asthma – GINA & Indian guidelines)
1. Stepwise Pharmacotherapy
| Step | Controller | Reliever | Target | Notes |
|---|---|---|---|---|
| 1 | Low‑dose inhaled corticosteroid (ICS) or leukotriene receptor antagonist (LTRA) | Short‑acting β₂‑agonist (SABA) PRN | Symptom control | Use spacer for <6 yrs. |
| 2 | Low‑dose budesonide or fluticasone | SABA | Reduce nighttime symptoms | Add LTRA if allergic rhinitis. |
| 3 | Medium‑dose budesonide or fluticasone + LABA (formoterol) | SABA | Prevent exacerbations | Consider montelukast if poor inhaler technique. |
| 4 | Medium‑dose budesonide + LABA + oral corticosteroid (OCS) taper | SABA | Severe symptoms | Add omalizumab if IgE‑mediated. |
| 5 | High‑dose budesonide + LABA + OCS taper | SABA | Persistent symptoms | Biologics (omalizumab, mepolizumab, benralizumab) for severe uncontrolled asthma. |
- Inhaler technique: Critical; assess at every visit.
- Spacer use: Improves drug deposition in children <6 yrs.
- Maintenance vs rescue: Avoid over‑use of SABA (>2 days/week) → indicates step‑up.
2. Non‑pharmacologic Measures
- Allergen avoidance: Dust‑mite filters, hypoallergenic bedding, pet restriction.
- Vaccinations: Influenza annually; pneumococcal vaccine.
- Vaccination against RSV: Palivizumab for high‑risk infants (premature, congenital heart disease).
- Education: Asthma action plan, trigger identification, inhaler technique.
- School policies: Allow rescue inhaler, notify teachers of asthma status.
3. Acute Exacerbation Management
- Mild: SABA PRN; reassess in 30 min.
- Moderate: SABA + oral antihistamine; consider oral steroids (prednisolone 1 mg/kg).
- Severe: Nebulised albuterol + ipratropium; IV methylprednisolone; oxygen; consider intubation if hypoxia or hypercapnia.
4. Monitoring & Follow‑up
- PEF variability: ≥20 % indicates uncontrolled asthma.
- FEV₁ decline >10 %: Review treatment.
- Annual review: Assess control, inhaler technique, adherence, comorbidities.
Complications
- Chronic airway remodeling → Fixed airflow limitation.
- Respiratory infections → Recurrent pneumonia, bronchiolitis.
- Growth retardation → Due to chronic steroid use.
- Psychosocial impact → School absenteeism, anxiety.
- Medication side‑effects: Oral thrush (ICS), adrenal suppression (OCS), growth suppression (high‑dose steroids).
High‑Yield Exam Points
- GINA 2024: Stepwise approach; avoid SABA monotherapy.
- FeNO: >25 ppb in >6 yrs suggests eosinophilic inflammation; guides steroid therapy.
- Asthma action plan: Must include rescue inhaler dose, when to seek urgent care, and when to adjust controller.
- Biologics: Indicated for severe, uncontrolled asthma with elevated IgE or eosinophils; omalizumab for IgE‑mediated, mepolizumab/benralizumab for eosinophilic phenotype.
- Differential diagnosis: Viral bronchiolitis, cystic fibrosis, foreign‑body aspiration, congenital heart disease.
- Spirometry in children: Age‑appropriate reference values; post‑bronchodilator improvement >12 % confirms reversible obstruction.
Practice Questions
A 7‑year‑old boy with intermittent wheeze uses a SABA twice a week. His PEF variability is 25 %. Which of the following is the most appropriate next step?
- A) Add a low‑dose inhaled corticosteroid (ICS)
- B) Increase SABA frequency to PRN
- C) Start oral prednisone
- D) Initiate leukotriene receptor antagonist (LTRA)
Answer: A – PEF variability >20 % indicates uncontrolled asthma; step‑up to low‑dose controller (ICS).
Which of the following is a characteristic feature of allergic asthma in children?
- A) Elevated serum IgG4
- B) FeNO >25 ppb
- C) Predominant neutrophilic inflammation
- D) Absence of atopy
Answer: B – FeNO >25 ppb reflects eosinophilic, Th2‑mediated inflammation typical of allergic asthma.
A 4‑year‑old girl with severe persistent asthma is not responding to high‑dose budesonide + LABA. Her IgE is 350 IU/mL. Which biologic therapy is most appropriate?
- A) Mepolizumab
- B) Benralizumab
- C) Omalizumab
- D) Dupilumab
Answer: C – Omalizumab targets IgE‑mediated allergic asthma; indicated when IgE is elevated.
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