In daily life, lung diseases like old chronic bronchitis (chronic bronchitis) and emphysema are often mentioned, and many people naturally equate them with COPD. However, this common understanding has biases. What is the actual connection between them, and what are the differences? How should they be correctly distinguished?

Similar "cousins"

Different "identities"

We can compare the relationship between chronic bronchitis, emphysema, and COPD to that of closely related but distinct members in a family.

Chronic Bronchitis: Chronic inflammation of the airways.

Chronic bronchitis refers to the chronic, non-specific inflammation of the mucosa and surrounding tissues of the trachea and bronchi. Imagine our airways (trachea and bronchi) being constantly stimulated by adverse factors such as tobacco, smoke, harmful dust, polluted air, viruses, bacteria, or cold weather over a long period. This can lead to an inflammatory response similar to repeatedly injured skin, such as congestion and edema of the mucosa, and a significant increase in mucus secretion. This can cause the airways to narrow and reduce airflow.

The main clinical signs of chronic bronchitis are cough, sputum, and wheezing, especially when patients experience significant morning cough, coughing up white foamy sputum or mucus sputum, with symptoms lasting for at least 3 months each year and for more than 2 consecutive years. It is more focused on describing the clinical state of airway inflammation and excessive secretion.

Emphysema: Over-inflation of "small balloons" in the alveoli.

Emphysema primarily occurs in the terminal bronchioles and alveoli of the lungs. Our lungs consist of billions of alveoli, each resembling a tiny balloon, connected to the outside world through extremely fine bronchioles. The overall structure is like a string of grapes. When harmful substances like tobacco damage the bronchioles, causing them to narrow and lose elasticity, the problem arises: during inhalation, the airways are passively expanded, allowing air to enter, but during exhalation, the airways collapse, making it difficult for air to be expelled. Over time, a large amount of gas gets trapped in the alveolar "small balloons," causing them to over-inflate, even rupture or fuse, forming emphysema.

This is like a balloon with reduced elasticity, making it hard to completely empty the air after blowing it up. The result is a significant decrease in the efficiency of gas exchange in the lungs, leading to oxygen deprivation in the body. Early-stage emphysema patients may experience shortness of breath after heavy physical activity, but as the condition progresses, difficulty breathing can occur even during daily activities or rest.

Chronic Obstructive Pulmonary Disease (COPD): The "Final Outcome" of Functional Limitation.

The full name of COPD is Chronic Obstructive Pulmonary Disease, a disease characterized by airflow limitation that is not completely reversible and progressively worsens. Airflow limitation is the core keyword of this disease, meaning the channels for air to enter and exit the lungs are obstructed. COPD is usually caused by abnormal airways and alveoli due to significant exposure to harmful particles or gases (mainly smoking).

Many COPD patients simultaneously exhibit symptoms of chronic bronchitis (cough, sputum) and emphysema (difficulty breathing). However, not everyone diagnosed with chronic bronchitis or emphysema has COPD. Only when pulmonary function tests confirm the presence of persistent airflow limitation (i.e., lung function indicators cannot return to normal even after bronchodilators are used) can a diagnosis of COPD be confirmed. If there is only chronic cough, sputum, or imaging findings suggestive of emphysema but normal pulmonary function, COPD cannot be diagnosed.

The "Gold Standard" for Diagnosis

Pulmonary function tests are indispensable

Why are pulmonary function tests so crucial? Because they can objectively and quantitatively assess whether there is airway obstruction and the severity of the obstruction. The main indicator for diagnosing chronic obstructive pulmonary disease (COPD) is the ratio of forced expiratory volume in the first second to forced vital capacity (FEV1/FVC). If this ratio remains below 70% after the use of bronchodilators, it indicates persistent airflow limitation, which is the "gold standard" for diagnosing COPD.

However, the public and even some grassroots doctors lack awareness and 重视度 regarding pulmonary function tests, leading to a large number of COPD patients being diagnosed with chronic bronchitis or emphysema for a long time without standardized pulmonary function evaluations, thus missing the best opportunities for early intervention and standardized COPD treatment. This has also directly resulted in the situation where, despite its significant harm, COPD has long been ignored by the public.

Serious situation

The Underestimated "Silent Killer"

Chronic Obstructive Pulmonary Disease (COPD) is far from a niche illness. According to the latest epidemiological data, it has become a common chronic disease on par with hypertension and diabetes. Despite this, the public widely exhibits the "three no's" phenomenon regarding COPD—unawareness, non-medical consultation, and non-treatment—often attributing persistent coughing and shortness of breath simply to "getting older" or "smoking too much," lacking awareness of proactive screening. The low prevalence of pulmonary function tests further exacerbates delayed diagnosis. Many patients often seek medical attention only when they experience severe breathing difficulties and a significant decline in mobility, by which time lung function has already been severely damaged, making treatment more challenging and drastically reducing the patient's quality of life, imposing a heavy burden on families and society.

In summary, chronic bronchitis, emphysema, and chronic obstructive pulmonary disease (COPD) are closely related but not entirely identical disease concepts. COPD can include the pathological changes of chronic bronchitis or emphysema, but they may not necessarily be COPD. The decisive basis for diagnosing COPD is persistent airflow limitation confirmed by pulmonary function tests. Faced with this hidden yet highly prevalent "breathing killer," we should stay alert, discard the misconception that "chronic bronchitis equals COPD," fully recognize the key role of pulmonary function tests in early diagnosis, and protect our precious respiratory health.