Emphysema is one of the main diseases included in the diagnosis "chronic obstructive pulmonary disease," or COPD. The other is chronic bronchitis. Most people with COPD have a combination of both. Some people have mostly chronic bronchitis, while others have mostly emphysema. In most cases, COPD is a disease caused by cigarette smoking.
Recent research suggests that pipe and cigar smoking may also contribute to lung abnormalities. The lungs have two basic functions: to bring in oxygen from the air and get rid of carbon dioxide (CO2) that is produced as a normal part of the body's metabolism. Both functions may be abnormal in COPD.
COPD is classified as mild, moderate, moderate-severe, severe, or very severe, and severity is determined mostly by the results of pulmonary function tests (PFTs, also know as lung function tests), which measure how much air a person can blow out of the lungs. COPD causes air to flow more slowly through the airways (tubes in the lungs), resulting in obstruction. The airways become like pipes that are partially blocked. COPD can cause other kinds of lung abnormalities. For example, emphysema results from the destruction of alveoli (air sacs) in the lungs, as well as the capillaries (small blood vessels) that run very close to them. When these air sacs and blood vessels are destroyed, oxygen has a more difficult time getting from the air into the bloodstream, which results in low blood oxygen levels." Also, in COPD it is harder for a person to breathe out carbon dioxide, and levels in the blood can rise and the blood becomes slightly more acidic. Doctors call this condition "chronic hypercapneic respiratory failure."
COPD progression varies greatly. Almost all smokers show some degree of lung damage, but only some smokers develop full-fledged COPD. Some people may not be diagnosed with COPD until they have reached an advanced stage. Many factors, including how much a person smoked, other kinds of exposures (heavy air pollution or other inhaled toxins), and individual genetic make up help determine how severe a person's COPD will become and how quickly it will progress. Currently, it is difficult to predict how quickly a person's COPD will stabilize or worsen. Nevertheless, one thing is clear: stopping smoking is the single most important thing a person can do to slow down COPD.
Because of the lung damage that occurs with COPD, people with COPD often have difficulty getting oxygen from the air into the bloodstream, which means less oxygen is available the rest of the body- Fatigue results more quickly. When the oxygen level falls very low, doctors call this condition "chronic hypoxemic respiratory failure. As a consequence of the low oxygen level or high carbon dioxide level, or as a consequence of lost blood vessels, the heart, especially the right side of the heart, must work harder than usual to pump blood. This can lead to heart failure over time. When the right side of the heart fails due to lung disease, doctors diagnose "cor pulmonale."
End-stage COPD is present when airflow in the lungs is below 30% of normal, or when cor pulmonale or respiratory failure is present. Other signs that COPD has reached a stage when life expectancy is shortened include very severe of shortness of breath, a poor ability to do physical activity, and weight loss or a low body mass index. Frequent exacerbations (episodes of sudden worsening usually associated with lung infections) also signal that COPD is reaching an advanced stage. Predicting the prognosis of end-stage COPD is very difficult. Some people live only a limited time while others may live for many years.
Treatments for people with advanced COPD include inhaled bronchodilators (albuterol, salmeterol, formoterol, ipratropium and tiotropium), which are safe and effective for most people. In patients with lung function below 50% of normal, inhaled steroids may be helpful. When hypoxemic respiratory failure or cor pulmonale is present, oxygen therapy can improve activity levels and lead to longer survival. Pulmonary rehabilitation, a specific exercise program, is very helpful to many people with COPD. Some patients, especially those with extensive emphysema, may improve with lung volume reduction surgery, in which large areas of damaged lung are cut out. Patients younger than 65-years-old may want to consider lung transplantation.
All patients with COPD, and especially those with advanced COPD, should discuss advance directives (living will and "do not resuscitate" status) with their loved ones and their health care providers. It may be difficult for patients with advanced COPD to recover from bouts of severe respiratory failure that require mechanical ventilation with a breathing tube, and knowing beforehand what you would want to do if that situation comes up will help you and your loved ones work with doctors and nurses select the most appropriate treatment for you if you get very sick.