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Chronic inflammatory airway disorder with variable and reversible airway obstruction, airway hyperresponsiveness, and chronic inflammation. Common in children and adolescents.
Chronic inflammatory airway disorder with variable and reversible airway obstruction, airway hyperresponsiveness, and chronic inflammation. Common in children and adolescents.
Risk Factors
Family history of asthma, atopy, eczema, or allergic rhinitis
Personal history of eczema, food allergies, or allergic rhinitis
Environmental exposures – passive smoke, air pollution, indoor allergens (dust mites, mould, pet dander)
Early viral infections (especially RSV or rhinovirus)
Prematurity and low birth weight
Obesity and sedentary lifestyle
Aetiology
Multifactorial – genetic predisposition to atopy combined with environmental exposures
Airway inflammation triggered by allergens, infections, cold air, exercise, or irritants
Often begins in early childhood and may persist or remit in adolescence
Pathophysiology
Airway inflammation causes bronchial hyperresponsiveness and narrowing
Mucosal oedema, smooth muscle hypertrophy, and mucus hypersecretion contribute to obstruction
Airflow limitation is reversible (spontaneously or with treatment)
Chronic inflammation may lead to airway remodelling and persistent symptoms
Diagnosis
Recurrent wheeze, cough (especially nocturnal), chest tightness, or dyspnoea
Symptoms vary in intensity and may be triggered by exercise, allergens, or viral infections
Improvement with bronchodilators supports diagnosis
Wheeze on auscultation may be present during episodes
For children >5 years, spirometry shows reversible obstruction (FEV1/FVC <0.8, FEV1 increase ≥12% post-bronchodilator)
Children <5 years: clinical diagnosis based on pattern, triggers, and response to trial of therapy
Differential Diagnosis
Viral-induced wheeze or bronchiolitis (especially in children <2 years)
Foreign body aspiration
Tracheomalacia or airway anomalies
Bronchopulmonary dysplasia (preterm infants)
Cystic fibrosis
Recurrent aspiration or GORD
Primary ciliary dyskinesia
Investigations
Usually clinical diagnosis in children
Spirometry if child is >5 years old and able to perform reproducible effort
FeNO (fractional exhaled nitric oxide) may support diagnosis in older children
Allergy testing if strong atopic component suspected
CXR not routinely indicated unless alternative diagnosis suspected
Management
Acute
Assess severity: mild, moderate, severe, or life-threatening (RCH guidelines)
Inhaled salbutamol via spacer (pMDI) preferred over nebuliser in most cases
Mild: salbutamol 2–6 puffs every 3–4 hrs
Moderate: salbutamol 6 puffs every 20 mins for 1 hr, then wean
Add ipratropium bromide for moderate–severe attacks
Oral corticosteroids (prednisolone 1–2 mg/kg up to 40 mg) for moderate or severe cases
Oxygen if SpO₂ <94%
Severe/life-threatening: escalate to nebulised salbutamol, IV steroids, magnesium sulfate, aminophylline or ICU transfer
Chronic
Stepwise approach based on symptom frequency and control (e.g. Australian Asthma Handbook)
Step 1: reliever (salbutamol) as needed
Step 2: low-dose inhaled corticosteroids (ICS)
Step 3: add LABA or increase ICS dose
Ensure correct inhaler technique and adherence
Develop personalised asthma action plan for families
Avoid triggers where possible (dust mites, smoke, allergens)
Annual influenza vaccination
Complications
Poor symptom control and frequent exacerbations
Hospitalisation or ICU admission for acute severe attacks
Airway remodelling in chronic poorly controlled asthma
Medication side effects (e.g. oral steroid toxicity, ICS-related growth suppression)
Impaired quality of life, school absence, sleep disruption
Psychosocial stress or anxiety due to chronic illness
Prognosis
Good prognosis with appropriate management
Many children outgrow symptoms by adolescence
Some continue into adulthood or develop fixed airway obstruction
Early and consistent ICS use improves long-term outcomes
Regular review and action plan essential to reduce exacerbation risk
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