Asthma
Why is this topic important?
Asthma is the most common chronic respiratory disease of childhood and one of the most frequently tested topics in MRCPCH examinations.
Candidates are expected to understand:
Pathophysiology
Diagnosis
Triggers
Acute asthma management
Long-term management
Asthma severity assessment
Life-threatening features
Asthma is also a common condition encountered in paediatric clinics, emergency departments and general practice.
Definition
Asthma is a chronic inflammatory disorder of the airways characterised by:
Variable airway obstruction
Airway inflammation
Bronchial hyper-responsiveness
Symptoms are usually recurrent and reversible, either spontaneously or following treatment.
Key MRCPCH Facts
Most common chronic respiratory disease in childhood.
Symptoms are often triggered by viral infections.
Airway inflammation is the underlying pathology.
Most children respond well to inhaled corticosteroids.
A silent chest is a life-threatening sign.
Asthma diagnosis is primarily clinical in younger children.
Inhaled corticosteroids are the cornerstone of preventer therapy.
Pathophysiology
Asthma results from chronic airway inflammation.
Exposure to triggers causes:
Airway Inflammation
Eosinophilic inflammation
Mucosal oedema
Increased mucus production
Bronchoconstriction
Airway smooth muscle contracts resulting in:
Wheeze
Breathlessness
Reduced airflow
Airway Hyper-responsiveness
Airways become excessively sensitive to stimuli such as:
Viral infections
Exercise
Allergens
Airway Remodelling
Long-standing uncontrolled asthma may result in structural airway changes.
Risk Factors
Personal Factors
Atopy
Eczema
Allergic rhinitis
Family history of asthma
Environmental Factors
Tobacco smoke exposure
Air pollution
House dust mite exposure
Pet allergens
Other Factors
Prematurity
Obesity
Viral respiratory infections
Common Triggers
Infectious
Viral upper respiratory tract infections
Environmental
Pollen
Dust mites
Animal dander
Smoke
Physical
Exercise
Cold air
Emotional
Stress
Anxiety
Clinical Features
Typical Symptoms
Wheeze
Cough
Breathlessness
Chest tightness
Characteristic Features
Symptoms worse at night
Symptoms vary over time
Symptoms triggered by exercise or viral infections
Improvement with bronchodilators
Examination Findings
Expiratory wheeze
Prolonged expiration
Increased work of breathing during exacerbations
Severity Assessment During Acute Asthma
Moderate Acute Asthma
Increased respiratory rate
Wheeze
Some difficulty speaking
Severe Acute Asthma
Marked breathlessness
Unable to complete sentences comfortably
Significant tachypnoea
Increased work of breathing
Life-Threatening Asthma
Red flag features include:
Silent chest
Cyanosis
Poor respiratory effort
Exhaustion
Altered consciousness
Hypotension
These require immediate senior review.
Differential Diagnosis
Respiratory
Bronchiolitis
Viral-induced wheeze
Pneumonia
Foreign body aspiration
Upper Airway
Croup
Stridor
Cardiac
Heart failure
Congenital heart disease
Investigations
Preschool Children
Diagnosis is usually clinical.
School-Aged Children
Spirometry
May demonstrate:
Obstructive pattern
Reversibility following bronchodilator
Peak Expiratory Flow
Useful for monitoring.
Allergy Assessment
May include:
Skin prick testing
Specific IgE testing
Management
Acute Asthma
Oxygen
Administer if hypoxic.
Salbutamol
First-line bronchodilator.
Usually given via:
Spacer device
Nebuliser in severe attacks
Oral Steroids
Examples:
Prednisolone
Reduce airway inflammation.
Escalation Therapy
May include:
Nebulised bronchodilators
Ipratropium bromide
Intravenous magnesium sulphate
Intravenous salbutamol
Aminophylline in selected cases
Long-Term Management
Step 1
Short-acting beta agonist (SABA) when required.
Step 2
Low-dose inhaled corticosteroid.
Step 3
Additional preventer therapy depending on age and guideline recommendations.
Step 4
Specialist review for poorly controlled asthma.
Asthma Education
Essential components include:
Inhaler technique
Trigger avoidance
Personalised asthma action plan
Recognition of deterioration
Complications
Acute
Respiratory failure
Pneumothorax
Hospital admission
Long-Term
Reduced quality of life
School absence
Exercise limitation
Rare
Death from severe asthma
Common Exam Traps
Trap 1
Night-time cough is an important asthma symptom.
Trap 2
A silent chest is a life-threatening sign.
Trap 3
Normal examination does not exclude asthma.
Trap 4
Most childhood asthma is triggered by viral infections.
Trap 5
Inhaled corticosteroids are preventers, not relievers.
Trap 6
Bronchiolitis usually affects infants; asthma is uncommon below 12 months.
One Minute Revision
Chronic inflammatory airway disease.
Wheeze, cough and breathlessness.
Symptoms vary over time.
Viral infections are common triggers.
Salbutamol = reliever.
Inhaled corticosteroids = preventer.
Silent chest = life-threatening asthma.
Related Question of the Day
A 9-year-old child presents with severe asthma. Which clinical sign indicates life-threatening asthma?
A. Wheeze
B. Tachycardia
C. Silent chest
D. Cough
E. Mild recession
Answer
C. Silent chest
Explanation
A silent chest indicates severely reduced airflow and is a life-threatening feature of acute asthma requiring urgent management.
Related Topics
Bronchiolitis
Pneumonia
Croup
Stridor
Allergic Rhinitis
Suggested References
NICE Asthma Guideline
BTS/SIGN Asthma Guideline
RCPCH Guidance
BNF for Children
Nelson Textbook of Pediatrics
Illustrated Textbook of Paediatrics
Kendig's Disorders of the Respiratory Tract in Children
Disclaimer
These notes are intended for MRCPCH revision and educational purposes only. They do not replace local, national or institutional guidelines. Clinical decisions should always be based on current guidance, senior advice and individual patient circumstances.
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