From the Guidelines
Asthma can indeed present with clear lungs on physical examination, even during an active asthma exacerbation, as the absence of audible wheezing does not rule out the disease. This phenomenon, sometimes called "silent chest," occurs because airflow may be too limited to generate audible wheezing 1. In mild asthma or between exacerbations, patients often have completely normal lung examinations despite having underlying airway hyperreactivity. Diagnosis of asthma relies on a combination of clinical history (recurrent episodes of wheezing, shortness of breath, chest tightness, and cough), pulmonary function testing (showing reversible airflow obstruction), and response to bronchodilators like albuterol 2.
Some key points to consider in the diagnosis of asthma include:
- Episodic symptoms of airflow obstruction or airway hyperresponsiveness are present 1
- Airflow obstruction is at least partially reversible, measured by spirometry 1
- History of symptoms such as cough, recurrent wheeze, recurrent difficulty in breathing, and recurrent chest tightness 1
- Symptoms occur or worsen in the presence of certain triggers, such as exercise, viral infection, or inhalant allergens 1
Peak flow monitoring can help detect airflow limitations even when lungs sound clear 2. Patients with normal-sounding lungs but symptoms suggestive of asthma should still undergo proper evaluation, as relying solely on auscultation can miss the diagnosis 3. The pathophysiology involves inflammation and hyperresponsiveness of airways that may not always produce audible findings, particularly in early disease or mild cases 4.
It is essential to note that symptoms and lung function represent different domains of asthma, and they correlate poorly over time in individual patients, so both need to be monitored by clinicians assessing asthma control in clinical practice 4. Lung function diary monitoring is to be encouraged in the diagnosis of asthma, and the upper limit of normal for amplitude percent mean with twice-daily monitoring is 8% 4.
From the Research
Asthma Presentation
- Asthma is a heterogeneous disease that can present with various symptoms and lung function test results 5
- The diagnosis of asthma is based on the combined presence of typical symptoms and objective tests of lung function, including spirometry with bronchodilator reversibility testing and peak flow measurement 5
- Asthma can present with clear lungs on physical examination, but this does not rule out the diagnosis of asthma 5
Lung Function Tests
- Spirometry with bronchodilator reversibility testing is the mainstay of asthma diagnostic testing for children and adults 5
- Peak flow measurement is a simple and useful test for diagnosing asthma, but it may not be specific for asthma 5
- Bronchial challenge testing is reserved for patients in whom the diagnosis of asthma is still suspected after negative spirometry and peak flow tests 5
Asthma Control
- Asthma control can be achieved with various treatments, including inhaled corticosteroids, long-acting beta2-agonists, and combination therapies 6, 7, 8, 9
- The choice of treatment depends on the severity of asthma symptoms and the patient's response to treatment 6, 7, 8, 9
- Regular monitoring of lung function and symptoms is essential to adjust treatment and achieve optimal asthma control 5