Diagnosis of Childhood Asthma
1. Physical Examination
A thorough physical examination is performed to rule out other causes of breathing difficulties, such as respiratory infections or chronic lung diseases. Clinicians also gather information about the pattern, frequency, and severity of symptoms, as well as any coexisting medical conditions.
2. Tests to Assess Lung Function
- Spirometry: Measures the volume of air exhaled after a deep breath and the rate of exhalation, helping detect airway narrowing.
- Peak flow: Uses a handheld device to assess how forcefully air can be exhaled. Lower readings may indicate worsening asthma or reduced lung function.
- Methacholine challenge: Involves inhaling methacholine, a substance that temporarily narrows the airways. A positive reaction supports an asthma diagnosis, even if initial lung function tests are normal.
- Bronchodilator response testing: Compares lung function before and after inhalation of a bronchodilator (e.g., albuterol). Improvement after treatment suggests reversible airway obstruction, a hallmark of asthma.
3. Additional Diagnostic Evaluations
- Imaging studies: Chest X-rays to detect structural abnormalities or infections.
- Allergy testing: Skin prick or blood tests to identify sensitivities to allergens such as dust mites, pollen, mold, or pet dander.
- Nitric oxide measurement: A breath test assessing nitric oxide levels, which may indicate airway inflammation.
- Sputum eosinophils: Analysis of coughed-up mucus for eosinophils, white blood cells often elevated in asthma.
- Exercise or cold-air provocation tests: Evaluates airway narrowing following vigorous exercise or exposure to cold air.