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Lung Health: Sorting Out COPD, Asthma, and Emphysema

Jonathan Vellinga, MD -

Lung Health: Sorting Out COPD, Asthma, & Emphysema

Breathing is automatic, and people expect to breathe - rarely considering what it would be like not to have the next intake of air. The dramatic failure of breath, such as in asthma attacks, is easy to spot. What is harder to notice is the slow progression of some lung conditions, which incrementally reduce the amount of oxygen in the bloodstream over such long periods that it often goes unnoticed until the condition is very advanced. Both dramatic and barely noticeable lung conditions can profoundly affect the human body. This article will cover three common lung conditions, tips for preventing lung diseases, and some specific treatment options.

The Lungs: A Crash Course

Human lungs look like an upside-down tree. The "trunk" is the tube that leads from the mouth and nose to the lungs, called the trachea. The trachea branches off into the two primary bronchi, one going to the left lung and one to the right. In the lungs, the bronchi branch and get smaller, forming bronchioles and, eventually, the alveoli. The alveoli are covered with capillaries, and it is here where oxygen that is breathed in is transferred into the circulatory system and where carbon dioxide is released as waste. These structures are delicate and can be damaged by inhaled chemicals and toxins.

diagram of the respiratory system

COPD - Umbrella Term and Standalone Disease

Much of the confusion regarding lung diseases stems from the term Chronic Obstructive Pulmonary Disease (COPD), which is both its own disease and a broad term that encompasses other lung diseases. What is common to COPD (and the lung diseases grouped under this term) is the persistent (chronic) blockage of airflow and the adverse effects on breathing (1). The blockage of airflow in the lungs can be caused by (2, 3):

  • Bronchial walls (airway tubes) that constrict or collapse

  • Collapse or damage of alveoli

  • Swelling, growth in thickness, or loss of elasticity of the bronchial walls

  • Buildup of mucus in the airways

If a lung disease involves obstructed airflow and shortness of breath, it can be grouped under the umbrella term of COPD. Chronic bronchitis and emphysema can be considered COPD, though they have different causes and can require other treatments. These lung diseases are diseases in their own right but also exist as subcategories of COPD. So, what determines the diagnosis of COPD versus one of the subcategories?

The standalone diagnosis of COPD may be given when there are symptoms of both chronic bronchitis and emphysema, rather than giving the patient two separate diagnoses.

Though people (and doctors) may use these terms interchangeably, it helps to clarify the definitions of the different lung diseases. Note, many words describing lung diseases use the word "pulmonary." The Latin word "Pulmo" means "lung."

COPD - Chronic Pulmonary Obstructive Disease - COPD is an umbrella term for a group of diseases involving chronic blockage of airflow and disrupted breathing. Also, COPD is a standalone diagnosis to indicate the extreme severity or irreversible nature of one of the diseases under the umbrella (emphysema or chronic bronchitis). There are four stages of COPD, with stage 1 being the early stage and stage 4 being very severe (2).

Asthma - Asthma is characterized by a sudden surge in symptoms (attacks) that have some triggering event. During the attack, airways constrict, inflammation may swell the airways, and mucus production in the lungs may increase and block the airways. Asthma is often called an inflammatory condition because inflammation is a crucial component. Asthma may be persistent or intermittent, allergic or non-allergic, and adult-onset or pediatric (4). Exercise-induced asthma is triggered by physical activity, whereas "occupational asthma" indicates that exposure to triggering events comes from irritating chemicals or dust at work. It's estimated that asthma attacks caused 1.6 million Americans to visit the emergency room in 2017 (5).

COPD/Asthma Dual Diagnosis - Although similar in some ways, asthma and COPD are two distinct diseases with separate causes. However, the two diseases can overlap, in which case a person will be diagnosed with both COPD and asthma (13, 14).

Chronic Bronchitis - This lung condition centers around the bronchial tubes, which become swollen and lined with excessive mucus. This process narrows the space where the lungs can take in air. Once the mucus is made, it is not removed quickly because the hair-like structures called cilia are damaged (often from smoking) (2).

Emphysema - This lung condition involves the breakdown of alveoli (air sacs), the structures at the ends of the airways in the lungs. Alveoli take in oxygen upon inhalation and release carbon dioxide as waste upon exhaling. In emphysema, the walls of the alveoli are damaged, reducing the amount of oxygen that comes into the body (2). Additionally, blockages can develop that trap oxygen in the lungs rather than letting it diffuse across the membranes of the alveoli. Trapped oxygen can puff out the chest, resulting in a "barrel-chested" shape (7). Emphysema is often unnoticed until more than 50% of the lung tissue has been damaged because the only symptom before that point is short