Diagnosing Chronic Obstructive Lung Disease

Diagnostic Tests

In spite of the widespread incidence and seriousness of chronic obstructive lung disease, studies strongly suggest that it is underdiagnosed, especially in women. Some experts recommend that any adult smoker who complains of a daily cough should be screened for COLD. In one 2002 study, nearly half of patients over 60 who regularly smoked had COLD.

Medical and Personal History

The doctor will request a history that evaluates the patient's risk factors. Risk factors include past and present smoking, low exercise capacity (e.g., whether the patient has trouble climbing stairs, the distance he or she can walk), and exposure to any industrial pollutants.

Physical Examination

Appearance. The appearance of the patients may be a clue to the condition. Bluish skin tone and swelling in the legs suggest chronic bronchitis. Healthy skin tone, but having an inflated chest, suggests emphysema.

The patient will also be asked to cough and produce sputum, if possible.

Chest Examination. The physician will next perform a simple examination of the chest area. Using a stethoscope, the physician will listen to the patient's breathing:

• Diminished or distant breath sounds are signs of emphysema. Tapping the chest will usually produce a hollow, drum-like sound.
• In chronic bronchitis, the physician is likely to hear wheezing or gurgling sounds.

Pulmonary Function Tests (Spirometry)

The best tests for determining the presence of COLD, and managing its response to treatment, are pulmonary function tests. The most common test is spirometry. Spirometry measures the volume and force of air as it is exhaled from the lungs. The patient is asked to breathe in and to exhale forcefully into an instrument several times. The force of the air is then monitored and measured.

Using the results, the physician determines two important values:

• The forced vital capacity (FVC). FVC is the maximum volume of air that can be exhaled (breathed out) with force, and is an indicator of lung size, elasticity, and how well the air passages open and close.
• The forced expiratory volume in one second (FEV1). FEV1 is the maximum volume of air exhaled in 1 second. Airflow is considered to be limited if the outflow of forced exhalation stays low over the course of one second. Steady but faster than normal decline in FEV1 over time characterizes COLD.
• Calculating a ratio of FEV1 to FVC is the best method for determining the presence and severity of COLD.