COPD, Emphysema, and Chronic Bronchitis: Obstructive Lung Disease
What Is COPD?
Chronic Obstructive Pulmonary Disease, or COPD, is a condition in which the airways and/or air sacs in the lungs are unable to function properly, making breathing difficult. The airways are the passages that transport air to, through, and from the lungs. The air sacs send inhaled oxygen into the blood and take up carbon dioxide waste to be exhaled. COPD is a progressive disease. However, the lung deterioration can be slowed and the symptoms treated, improving the quality of life for the patient.
There are two major conditions that are classified as COPD. Chronic bronchitis and emphysema may occur on their own, but they often occur together. In chronic bronchitis, the airways are inflamed and swollen. They are also partially filled with mucus. Some people experience temporary (acute) bronchitis due to an infection, but long-lasting (chronic) bronchitis is part of COPD. In emphysema, air sacs are damaged and destroyed.
Both the chronic bronchitis and the emphysema components of COPD are generally caused by smoking for many years or by exposure to secondhand smoke. Other factors may cause chronic obstructive pulmonary disease, too, including inhaling polluted air or toxins for a long time. Some people have a genetic problem that makes them more susceptible to smoke damage.
The Respiratory System
The air that we inhale through our nose or mouth enters the back of the throat and travels into the larynx or voice box. From here, the air flows into the trachea, which is also known as the windpipe. The trachea transports the air into two tubes known as the primary bronchi. One primary bronchus goes to each lung, where it branches into narrower bronchi. The branching continues, creating smaller and smaller airways. The tiniest branches of the airways are called bronchioles.
The bronchioles send inhaled air into sacs called alveoli. Oxygen is passed into the bloodstream through the thin walls of the alveoli. Carbon dioxide moves from the blood into the alveoli to be exhaled. The alveoli are covered with blood vessels known as capillaries, which like the alveoli have thin walls that make gas exchange easy.
The diaphragm is a large, sheet-like muscle located under the lungs. It's part of the respiratory system and is the main muscle of respiration. The medulla oblongata in the brain stimulates the diaphragm to contract at regular intervals. As the diaphragm contracts, it moves downwards, causing the lungs to expand. This expansion of the lungs enables air to enter them during inhalation. When the medulla oblongata stops sending a signal to the diaphragm, the muscle relaxes. As it does so, it moves upwards and pushes air out of the lungs during exhalation.
Obstructive and Restrictive Lung Diseases
COPD, chronic bronchitis, and emphysema are said to be obstructive lung diseases as opposed to restrictive lung diseases. Obstructive diseases primarily affect the passage of air out of the lungs, while restrictive diseases affect the passage of air into the lungs.
In an obstructive lung disease, a person has trouble exhaling all the air from their lungs, either because the lungs are damaged or because the airways have become too narrow. As a result, a large amount of old air remains in the person's lungs. This air has already given up most of its oxygen. In a restrictive lung disease a person cannot fully expand their lungs and therefore cannot obtain enough oxygen during inhalation.
In chronic bronchitis, the bronchi are inflamed. The lining of the bronchi is swollen and produces a large quantity of thick mucus. Mucus is a normal component of the airways and has useful functions, but it becomes a problem if too much is made or if it becomes thick and sticky,
A person suffering from chronic bronchitis coughs frequently in an attempt to get rid of the mucus. The mucus is known as sputum or phlegm when it's coughed up. The person may have a tight feeling in their chest and it may be difficult for them to breathe. They may also wheeze as they breathe.
The definition of "chronic" bronchitis varies slightly according to different opinions, but in general bronchitis is said to be chronic if the person coughs and produces sputum every day—or on most days—for at least three months in a year and for at least two years in a row.
What Is Chronic Bronchitis?
The alveoli are located close together in the lungs, forming clusters that look something like bunches of grapes. Although alveoli are small, there are so many of them—about 300 million to 400 million in each lung—that the total surface area of all their walls is very large. This feature allows for enough gas exchange between the alveoli and the blood to keep us alive and active.
In emphysema, the walls of some of the alveoli break down. Therefore there is less surface area for gas exchange between the blood and the alveoli. Large, irregularly shaped cavities often appear amongst the alveoli. The walls of the intact alveoli may lose their elasticity. Alveoli normally expand as they fill with inhaled air and then shrink as the air is exhaled. The alveoli may remained stretched in a patient with emphysema. This makes it hard for the patient to expel air.
What Is Chronic Obstructive Pulmonary Disease or COPD?
COPD Symptoms and Flare-Ups
The symptoms of untreated COPD or of either disease component on its own are often worse when a person tries to exercise, since exercise increases the body's oxygen requirement. A person with chronic obstructive pulmonary disease may experience shortness of breath even during a slight exertion. It's very important that the person doesn't ignore his or her symptoms, because the sooner they receive treatment for COPD the better the outlook for their future.
People with COPD may experience times when their symptoms suddenly get worse, even when they're not exercising. These periods are known as flare-ups or exacerbations and can sometimes require an emergency hospital visit. Coughing may increase and more mucus may be released. The mucus may be thicker than usual and have a different color. Breathing may be increasingly difficult. Flare-ups are usually caused by a new irritant to the lungs, such as a respiratory infection or exposure to increased air pollution. A patient needs to form an action plan for dealing with flare-ups in cooperation with their doctor.
What Happens in the Lungs During COPD?
The Four Stages of COPD
There are different stages of COPD, ranging from mild to very severe. Ideally treatment should begin while a person is in the mild stage. An organization called the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classifies the stages of obstructive lung disease as shown in the table below. The classification is widely used. The ability to exhale is determined by a patient blowing into a device called a spirometer.
The Stages of Chronic Obstructive Lung Disease
Possibly, a chronic cough that brings up mucus
Ability to exhale is 80% of normal
A chronic cough that brings up a large amount of mucus
Ability to exhale is 50% to 79% of normal
Shortness of breath, especially during exercise; occasional flare-ups
A chronic cough that brings up a large amount of mucus
Ability to exhale is 30% to 49% of normal
Shortness of breath; frequent flare-ups, which may be severe; fatigue
Four (Very Severe)
A chronic cough that brings up a large amount of mucus
Ability to exhale is less than 30% (or less than 50% and accompanied by chronic respiratory failure, which is caused by excess carbon dioxide in the lungs)
Severe shortness of breath; life-threatening flare-ups; cyanosis (a blue color in the skin); edema (fluid buildup in the lower limbs); weight loss
A COPD Overview
Causes of Chronic Obstructive Pulmonary Disease
By far the most common cause of chronic obstructive pulmonary disease is smoking for many years or chronic exposure to secondhand smoke. Long-term exposure to other lung irritants such as toxic workplace vapors or dangerous air pollution can also cause COPD.
A fibrous protein called elastin surrounds the airways and is present in the walls of the alveoli. This protein enables structures to return to their original shape after they're stretched. An enzyme called elastase breaks down the elastin. Smoking causes inflammation and stimulates inflammatory cells to releases elastase, which causes deterioration in lung structures.
A few people have a genetic problem that reduces their production of a protein called alpha-1 antitrypsin (AAT). AAT has the ability to block the action of elastase. This means that smokers who also have an AAT deficiency have an increased likelihood of developing COPD. Nonsmokers with an AAT deficiency have an increased risk of developing chronic obstructive lung disease, too.
Anyone who has breathing problems or who suspects that they have COPD should visit a doctor. The doctor's diagnosis and treatment are vital.
COPD Treatment: First, Stop Smoking
The first step in treating COPD—which is vital—is to stop smoking. Researchers stress that it's never too late to quit smoking. Once the lungs are no longer exposed to tobacco smoke, the rate of lung tissue deterioration generally slows. However, the lung damage that has already occurred isn't reversed when smoking ceases. If a person continues to smoke, lung deterioration will continue at an accelerated rate and may become life threatening.
Research suggests that from 15% to 25% of smokers develop COPD. Some researchers think that the percentage is actually much higher, since some people don't visit their doctor when breathing becomes difficult and therefore don't get a diagnosis.
Quitting smoking may be difficult for long-term smokers, who are most likely to develop chronic obstructive pulmonary disease. It's very important for reducing lung deterioration, however. A patient should use all the help available to end their smoking habit. Once they no longer smoke, the person should be able to deal with the symptoms that have developed up to that time. Of course, the best plan is to never start smoking or to quit before any symptoms of COPD appear.
Some Other Possible Treatments
Inhaled forms of medications are frequently prescribed to help relieve symptoms. Bronchodilators expand the airways, allowing more oxygen to reach the lungs. Corticosteroids reduce inflammation. Inhalers containing a combination of these two types of medications are often used. There are other inhaled and oral medications that may be helpful as well. AAT may be administered to patients who lack the protein.
A program known as pulmonary rehabilitation may be very helpful for a COPD patient. This program involves a combination of strategies to improve the patient's quality of life. It teaches useful breathing techniques and exercises and includes physical therapy and instructions for the proper use of medications and respiratory devices. An exercise program can be very beneficial for COPD patients, but it's important to follow a medical professional's advice about exercise type, duration, and frequency.
A person with COPD should ask their doctor whether getting an annual flu vaccine would be beneficial. They may need to inhale supplemental oxygen at night and perhaps during the day as well. In certain cases surgery may be performed to remove damaged areas in lungs. A lung transplant may be performed if a lung is severely damaged and if a new lung is available. Hopefully researchers will soon discover new ways to help people with chronic obstructive pulmonary disease.
Tips for Living With Chronic Obstructive Pulmonary Disease
References and Resources
Questions & Answers
Is chronic bronchitis contagious?
Chronic bronchitis is very likely not contagious, while acute bronchitis may be. The chronic condition is generally caused by long-term irritation of the airways by smoke, chemicals, or dust of some kind. If no infectious agent is present, the condition isn’t infectious. Acute bronchitis is often caused by an infection, however. The pathogen causing the disorder (a virus or sometimes a bacterium) can be passed to someone else, making them sick.
© 2012 Linda Crampton