Asthma in Children (Paediatrics)
Definition
Asthma is a chronic inflammatory disease of the airways characterized by reversible airway obstruction, bronchial hyperresponsiveness, and airway inflammation, leading to recurrent episodes of wheezing, breathlessness, chest tightness, and cough, especially at night or early morning.
In children, asthma is one of the most common chronic respiratory diseases and a major cause of school absenteeism and hospital admissions.
Pathophysiology
Asthma results from chronic airway inflammation and hyperreactivity.
1. Airway Inflammation
Inflammatory cells involved:
- Mast cells
- Eosinophils
- T-lymphocytes (Th2 cells)
- Neutrophils (in severe asthma)
Inflammation causes:
- Edema of airway mucosa
- Mucus hypersecretion
- Damage to airway epithelium
2. Bronchial Hyperresponsiveness
Airways become excessively sensitive to triggers such as allergens, infections, cold air, and exercise.
3. Airway Obstruction
Three main mechanisms:
- Bronchial smooth muscle contraction
- Mucosal edema
- Mucus plugging
4. Airway Remodeling (chronic disease)
- Smooth muscle hypertrophy
- Subepithelial fibrosis
- Goblet cell hyperplasia
These changes may lead to partially irreversible obstruction if asthma is poorly controlled.
Causes and Triggers
Genetic Predisposition
- Family history of asthma
- Atopy
- Allergic diseases
Environmental Triggers
- Dust mites
- Pollen
- Animal dander
- Mold
Infectious Triggers
- Viral infections (common cause in children)
- Respiratory viruses like Respiratory Syncytial Virus
Physical Triggers
- Cold air
- Exercise
- Air pollution
- Tobacco smoke
Other Triggers
- Emotional stress
- Strong odors
- Certain drugs
Clinical Features
Symptoms
Typical symptoms include:
- Recurrent wheezing
- Shortness of breath
- Chest tightness
- Cough, especially at night or early morning
Key Pediatric Clues
- Night-time cough
- Exercise intolerance
- Recurrent bronchitis
- Wheezing with viral infections
Signs
During an asthma attack:
- Tachypnea
- Tachycardia
- Expiratory wheeze
- Prolonged expiration
- Use of accessory muscles
- Intercostal retractions
Severe Attack Signs
- Silent chest
- Cyanosis
- Drowsiness
- Poor respiratory effort
These indicate life-threatening asthma.
Classification of Asthma Severity
Intermittent
- Symptoms <2 days/week
- Night symptoms <2/month
- Normal lung function
Mild Persistent
- Symptoms >2 days/week
- Night symptoms 3–4/month
Moderate Persistent
- Daily symptoms
- Night symptoms >1/week
Severe Persistent
- Continuous symptoms
- Frequent night symptoms
Investigations
1. Pulmonary Function Tests
Most useful test.
Spirometry Findings
- Reduced FEV1
- Reduced FEV1/FVC ratio
- Reversibility after bronchodilator (>12%)
2. Peak Expiratory Flow Rate (PEFR)
Used for monitoring.
- Reduced during attacks
- Improvement after bronchodilator
3. Allergy Testing
- Skin prick test
- Serum IgE levels
4. Blood Tests
- Peripheral eosinophilia
- Elevated IgE
5. Chest X-ray
Usually normal but may show:
- Hyperinflation
- Flattened diaphragm
Differential Diagnosis
Conditions mimicking asthma:
- Bronchiolitis
- Cystic Fibrosis
- Foreign Body Aspiration
- Primary Ciliary Dyskinesia
- Congenital Heart Disease
Management
Management includes:
- Acute attack treatment
- Long-term control therapy
- Trigger avoidance
- Patient education
Treatment of Acute Asthma Attack
1. Oxygen
Indication:
- SpO₂ <94%
Dose:
- Humidified oxygen via mask
Goal:
- Maintain saturation >94%
2. Short Acting β2 Agonists (SABA)
Example: Salbutamol
Mechanism
Stimulates β2-adrenergic receptors → bronchodilation.
Dose
Nebulization:
- 2.5 mg (<5 years)
- 5 mg (>5 years)
Repeat every 20 minutes for 3 doses initially.
Pharmacokinetics
- Onset: 5 minutes
- Peak: 30 minutes
- Duration: 4–6 hours
Adverse Effects
- Tremor
- Tachycardia
- Hypokalemia
Contraindications
- Severe cardiac arrhythmias
Monitoring
- Heart rate
- Oxygen saturation
- Clinical improvement
3. Anticholinergic Bronchodilator
Example: Ipratropium Bromide
Mechanism
Blocks muscarinic receptors → prevents bronchoconstriction.
Dose
Nebulization:
- 250–500 mcg every 20 minutes (first hour)
Adverse Effects
- Dry mouth
- Blurred vision
4. Corticosteroids
Example: Prednisolone
Mechanism
Reduces airway inflammation and edema.
Dose
- 1–2 mg/kg/day orally
- Max 40–60 mg
Duration
Usually 3–5 days
Adverse Effects
Short term:
- Gastric irritation
- Mood changes
Long term:
- Growth suppression
- Adrenal suppression
Monitoring
- Growth
- Blood pressure
- Blood glucose
Long-Term Control Therapy
Stepwise Approach
Step 1
- SABA as needed
Step 2
- Low dose inhaled corticosteroid
Example: Budesonide
Dose:
- 200–400 mcg/day
Mechanism:
- Suppresses airway inflammation
Step 3
- Low dose ICS + LABA
Example LABA: Salmeterol
Mechanism:
- Long acting bronchodilation (12 hours)
Step 4
- Medium/high dose ICS + LABA
Step 5
- Add biologic therapy
Example: Omalizumab
Mechanism:
- Anti-IgE monoclonal antibody
Indication:
- Severe allergic asthma
Non-Pharmacologic Management
Trigger Avoidance
- Avoid dust mites
- Reduce exposure to pets
- Avoid tobacco smoke
- Control indoor allergens
Environmental Control
- Use air filters
- Wash bedding in hot water
- Reduce humidity
Vaccination
- Influenza vaccine
- Pneumococcal vaccine
Asthma Education
Important components:
- Correct inhaler technique
- Use of spacer devices
- Written asthma action plan
- Recognizing early symptoms
Complications
- Status asthmaticus
- Respiratory failure
- Pneumothorax
- Growth retardation (due to steroids)
Prognosis
- Many children outgrow asthma
- Some develop persistent adult asthma
- Good control with proper treatment
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