Definition

Asthma is the most common chronic inflammatory disease of the lungs in children. It is a heterogeneous condition, meaning it can vary greatly between individuals.

Three key processes occur in asthma:

1. Reversible bronchoconstriction (narrowing of airways)

2. Chronic airway inflammation

3. Increased mucus (secretions)

   Basic Pathophysiology

When a trigger is present:

• The immune system is activated.

• Dendritic cells stimulate T-lymphocytes.

• Inflammatory mediators such as histamine, leukotrienes, prostaglandins, and enzymes are released.

This leads to:

• Airway narrowing

• Swelling of airway lining

• Increased mucus production

The final result is airflow obstruction, which causes asthma symptoms.

Very basic at Cellular Levels

Trigger Factors and Risk Factors

Identifying trigger factors is a key part of history-taking. Common triggers include:

• Viral infections

• Allergens (dust mites, pollen, pets)

• Exercise

• Cold air

• Smoke and pollution

Risk factors help guide long-term management and prevention strategies. Identifying and avoiding triggers, where possible, can significantly improve asthma control.

Clinical Presentation

Typical symptoms include:

• Recurrent cough (often dry)

• Wheezing

• Shortness of breath

• Chest tightness

A supportive family history of asthma or atopy strengthens the clinical suspicion.

Diagnosis !

1. History – The Most Important Tool

The diagnosis of asthma is primarily clinical. Investigations support the diagnosis but do not replace a good history.

2. Spirometry

Spirometry measures lung function, especially how much air a child can blow out.

• FEV₁: Air exhaled in the first second

• FVC: Total air exhaled

• FEV₁/FVC ratio:

  • 75% is usually normal

  • <75% suggests airway obstruction

If obstruction is present, a reversibility test is performed after giving a bronchodilator. An improvement of ≥12% supports asthma diagnosis.

Important points:

• Normal spirometry does not exclude asthma

• The child may be asymptomatic during testing

• Asthma is not the only cause of airway obstruction

3. Fractional Exhaled Nitric Oxide (FeNO)

FeNO measures nitric oxide released during allergic airway inflammation.

• Can be performed in children as young as 3 years

• Helps assess airway inflammation

• Has moderate diagnostic accuracy

• Useful in monitoring treatment response

However:

• FeNO can be falsely elevated in certain conditions

• High FeNO alone does not confirm asthma

• Test technique and clinical context are crucial.

4. Allergy Testing

Allergy testing helps identify trigger factors, not diagnose asthma.

• Blood eosinophils may support allergic inflammation

• Specific allergy testing is useful when triggers are suspected

• Results can guide avoidance and management strategies.

Revisiting the Three Clinical Scenarios

1. 4-year-old with episodic wheeze
   Most likely recurrent viral-induced wheeze. No clear evidence of asthma at present.

2. 9-year-old referred for spirometry
   Spirometry is helpful, but diagnosis depends mainly on history. Normal spirometry does not rule out asthma.

3. 13-year-old with very high FeNO
   Despite high FeNO, the child had no symptoms and was on regular preventer treatment. This raises questions about:

   • Test accuracy

   • Technique

   • Whether FeNO alone should guide diagnosis

Principles of Asthma Management

Asthma management is not just about medication—it includes:

• Detailed history

• Appropriate investigations

• Individualised treatment plan

• Regular follow-up

Key principles:

1. Avoid trigger factors where possible

2. Treat airway inflammation

   • Inhaled corticosteroids for long-term control

   • Systemic steroids for acute attacks

3. Treat bronchoconstriction

   • Bronchodilators for symptom relief

4. Leukotriene modifiers (e.g., montelukast) can help selected patients

   There is one thing above all -

   Education, Education and Education for all of us and parents.