How is it Diagnosed?
Chronic bronchitis is diagnosed primarily through a detailed clinical history and physical
examination. The hallmark criterion is a productive cough lasting for at least three
months in two consecutive years, in the absence of other underlying diseases. The
diagnosis begins with a thorough patient history including smoking habits, occupational
exposures, and recurrent respiratory infections.
Physical examination may reveal wheezing, prolonged expiratory phase, and coarse
crackles. Pulmonary function tests (PFTs), especially spirometry, are crucial for
assessing airflow limitation. A reduced FEV1/FVC ratio indicates obstructive airway
disease, which supports a diagnosis of chronic bronchitis, particularly when reversible
airflow obstruction is excluded.
Chest X-ray and high-resolution computed tomography (HRCT) may be used to rule out
other causes such as tuberculosis, bronchiectasis, or interstitial lung disease. Sputum
analysis helps detect bacterial infections or inflammatory markers and may guide
antibiotic therapy. Arterial blood gas analysis is considered in advanced disease to
assess oxygen and carbon dioxide levels.
In some cases, testing for alpha-1 antitrypsin deficiency is recommended, especially in
non-smokers or those with a family history. Pulse oximetry and 6-minute walk tests
provide information about functional status and hypoxia. The Global Initiative for
Chronic Obstructive Lung Disease (GOLD) criteria also assist in classifying the severity
and guiding management.