Characteristic Features of Asthma
The most characteristic feature of asthma among the given options is polyphonic wheezing with exercise (Option D), as polyphonic wheeze is described as a cardinal sign of asthma, and exercise is a classic trigger for asthma symptoms. 1
Why Polyphonic Wheezing with Exercise is Most Characteristic
Polyphonic wheeze is specifically identified as a cardinal sign of asthma that should be documented in clinical notes, typically described as diffuse, polyphonic, bilateral, and particularly expiratory. 1
The hallmark of asthma is that symptoms are provoked by triggers including exercise, making exercise-induced wheezing highly characteristic of the disease. 1
During exacerbations, patients will often have wheeze and reduced lung function, with the presence of wheeze being a defining clinical feature. 1
Why the Other Options Are Less Characteristic
Option A: Continuous Productive Cough
- Asthma typically presents with non-productive cough, not continuous productive cough. 2
- While cough is a symptom of asthma, it is variable and intermittent rather than continuous. 1
- Continuous productive cough is more suggestive of other conditions like bronchiectasis, COPD, or chronic bronchitis. 1
Option B: Normal Chest X-Ray Between Episodes
- While this can occur in asthma, it is not specific to asthma and can be seen in many intermittent respiratory conditions. 1
- The diagnosis of asthma is clinical and there is no confirmatory radiographic investigation. 1
- Outside acute episodes, there may be no objective signs of asthma, but this is a negative finding rather than a characteristic feature. 1
Option C: Recurrent Respiratory Infection
- Recurrent respiratory infections are not characteristic of asthma itself. 1
- While viral infections can trigger asthma symptoms, recurrent infections suggest other diagnoses such as bronchiectasis, cystic fibrosis, or immunodeficiency. 1
Key Clinical Pitfalls to Avoid
Do not confuse asthma with conditions that cause continuous productive cough (such as bronchiectasis or COPD), as asthma cough is typically dry and variable. 1, 2
Remember that the absence of wheeze between episodes does not exclude asthma, but the presence of polyphonic wheeze during symptomatic periods or with triggers is highly characteristic. 1
Exercise-induced symptoms are so characteristic of asthma that exercise testing (six minutes of running) is used as a diagnostic test, looking for a decrease in peak flow or FEV1 after exercise. 1