Chronic obstructive pulmonary disease, or COPD, accounts for over 100,000 deaths per year in the United States alone, making it the fourth leading cause of death. COPD is actually a group of diseases that include chronic bronchitis, emphysema, and asthmatic bronchitis. Each of these diseases shares a common characteristic, which is obstruction to airflow out of the lungs, causing shortness of breath.
In over 90 percent of cases, COPD is the result of smoking. The death rate has increased most significantly in women, which reflects the increased number of women who smoke. There are, however, less common causes of COPD, such as cystic fibrosis, bronchiectesis, and genetic forms of emphysema. Below are answers to some of the most common questions that people ask their doctors about COPD.
What is the relationship between COPD and smoking?
There is a direct causal relationship between COPD and smoking. Even the tobacco manufacturers now freely acknowledge this relationship. Other risk factors, such as genetic causes, air pollution, and childhood infections, pale in comparison to the risk of smoking. Nevertheless, there is a marked variability in the degree of damage smoking will do in an individual person. Only about 15 percent of chronic smokers will go on to develop clinically significant COPD. Why some smokers seem to be protected against developing COPD is under investigation.
My doctor told me I have COPD. Is it too late to quit smoking?
NO!! Once diagnosed with COPD, it is vitally important to quit smoking. COPD can be a progressive, debilitating disease. It can start simply as a difficulty with chores such as climbing steps, and progress to the point where supplemental oxygen is necessary to breathe at rest.
The rate of this progression will be rapid if you continue to smoke. If you quit smoking, the rate of COPD progression can be markedly slowed. Some studies even suggest a slight improvement in lung function initially after stopping smoking. More importantly, though, the decline in lung function over time can be reduced to a nearly normal rate after smoking cessation.
I don't have any symptoms but I smoke two packs per day. Am I in the clear?
No again! COPD can be asymptomatic, especially in the early stages. The lung has a great deal of reserve. Many patients do not report any symptoms until they have lost over 50 percent of their lung function. Some patients report that they are asymptomatic, but, in reality, they simply stop doing the things they used to do because of shortness of breath. The best way to tell if you have COPD is to measure your lung function by doing a breathing test called spirometry. Spirometry is a simple test of lung function where you are asked to breathe as fast and as hard as you can into a tube after taking a deep breath. Some doctors believe strongly in the value of screening spirometry for all smokers and patients with chronic respiratory symptoms.
What is emphysema? What is the difference between emphysema and COPD?
Emphysema is one type of COPD. It refers to the destruction of the lung alveoli by smoking. Alveoli are the tiny sacs in your lungs where gases are exchanged between the lungs and the bloodstream. This exchange helps your lungs deliver oxygen to all the cells of your body and remove carbon dioxide, which is a byproduct produced after the cells have used the oxygen to create energy. When emphysema develops, the lung loses its ability to effectively exchange gas with the bloodstream. This leads first to a decrease in oxygen and, eventually, a buildup of carbon dioxide in the body. You can partially compensate for this by breathing harder and faster, but, of course, this causes shortness of breath.
Emphysema is only one of the harmful effects of smoking on the lungs. As you will see below, smoking also causes chronic bronchitis and asthmatic bronchitis. Most patients have a mixture of all three conditions, and we group them together under the umbrella term COPD. However, certain patients seem to suffer from one of these illnesses more significantly than the others. Patients who primarily have shortness of breath-with little mucus, wheezing, or other clinical features-may have emphysema as the predominant component of their COPD.
What is chronic bronchitis?
The lung has a series of branching tubes that deliver air to and from the atmosphere to the alveoli. These tubes are called bronchi. The cells that line the bronchi are made up of special cells with hairy filaments on them called cilia, as well as special cells that secrete mucus. The function of these cells is to protect the lung from pollutants, allergens, and microorganisms that we inhale from the environment.
Smoking can damage the ciliated cells and cause abnormal growth of the mucous cells. Thus, the lung starts secreting excess mucus while the ciliated cells lose their ability to push the mucus along. The result is chronic bronchitis, where the patient has excessive amounts of mucus in the lung and the only way to get rid of the mucus is to cough. This cough is usually worse in the morning. Also, the damage to the cilia predisposes the patients to frequent infections, where the sputum becomes yellow or green after invasion by bacteria.
Some patients may predominantly complain of mucus production and frequent infections, and may be less bothered by shortness of breath. These patients may have predominantly chronic bronchitis and little emphysema. Doctors can sometimes further differentiate this diagnosis by performing pulmonary function testing.
What is asthmatic bronchitis?
The bronchi of the lung can become inflamed because of the noxious effects of tobacco smoke. This chronic inflammation can lead to intermittent attacks where the muscles of the bronchi contract, excess mucus is secreted, and fluid seeps into the wall of the bronchus from leaky blood vessels. The result is wheezing, or asthma "attack".
Patients who predominantly complain of intermittent wheezing, and are relatively asymptomatic in between attacks may have predominantly asthmatic bronchitis. We usually reserve the term "asthmatic bronchitis" for patients who have intermittent wheezing as a component of their COPD from smoking.
I'm a smoker but my spirometry results are normal. Now am I free and clear?
No! Your lung function may still decline over time, so repeat tests every few years are advisable. Even if you don't develop COPD, you are still at risk from other harmful effects of smoke, including heart disease, lung cancer, premature skin aging, stroke, and a host of other diseases.
It sounds like COPD is irreversible. Can it be treated?
Some of the damage from COPD is irreversible. There is no cure at the present time for COPD, which is why I stress early detection and smoking cessation. Nevertheless, there are a number of treatments that can greatly improve the symptoms and quality of life of patients with COPD. These include oral and inhaled medications, oxygen therapy, and pulmonary rehabilitation.