Chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease (COPD) is a type of obstructive lung disease characterized by long-term breathing problems and poor airflow. The main symptoms include shortness of breath and cough with sputum production. COPD is a progressive disease, meaning it typically worsens over time. Eventually, everyday activities such as walking or getting dressed become difficult. Chronic bronchitis and emphysema are older terms used for different types of COPD. The term "chronic bronchitis" is still used to define a productive cough that is present for at least three months each year for two years. Those with such a cough are at a greater risk of developing COPD. The term "emphysema" is also used for the abnormal presence of air or other gas within tissues.
The most common cause of COPD is tobacco smoking, with a smaller number due to factors such as air pollution and genetics. In the developing world, one of the common sources of air pollution is poorly vented heating and cooking fires. Long-term exposure to these irritants causes an inflammatory response in the lungs, resulting in narrowing of the small airways and breakdown of lung tissue. The diagnosis is based on poor airflow as measured by lung function tests. In contrast to asthma, the airflow reduction does not improve much with the use of a bronchodilator.
Most cases of COPD can be prevented by reducing exposure to risk factors. This includes decreasing rates of smoking and improving indoor and outdoor air quality. While treatment can slow worsening, no cure is known. COPD treatments include smoking cessation, vaccinations, respiratory rehabilitation, and often inhaled bronchodilators and steroids. Some people may benefit from long-term oxygen therapy or lung transplantation. In those who have periods of acute worsening, increased use of medications, antibiotics, steroids, and hospitalization may be needed.
As of 2015, COPD affected about 174.5 million people (2.4% of the global population). It typically occurs in people over the age of 40. Males and females are affected equally commonly. In 2015, it resulted in 3.2 million deaths, up from 2.4 million deaths in 1990. More than 90% of these deaths occur in the developing world. The number of deaths is projected to increase further because of higher smoking rates in the developing world, and an ageing population in many countries. It resulted in an estimated economic cost of $2.1 trillion in 2010.
Signs and symptoms
The most common symptoms of COPD are shortness of breath, and a cough that produces sputum. These symptoms are present for a prolonged period of time and typically worsen over time. It is unclear whether different types of COPD exist. While previously divided into emphysema and chronic bronchitis, emphysema is only a description of lung changes rather than a disease itself, and chronic bronchitis is simply a descriptor of symptoms that may or may not occur with COPD.
A chronic cough is often the first symptom to develop. Early on it may just occur occasionally or may not result in sputum. When a cough persists for more than three months each year for at least two years, in combination with sputum production and without another explanation, it is by definition chronic bronchitis. Chronic bronchitis can occur before the restricted airflow and thus COPD fully develops. The amount of sputum produced can change over hours to days. In some cases, the cough may not be present or may only occur occasionally and may not be productive. Some people with COPD attribute the symptoms to a "smoker's cough". Sputum may be swallowed or spat out, depending often on social and cultural factors. In severe COPD, vigorous coughing may lead to rib fractures or to a brief loss of consciousness. Those with COPD often have a history of "common colds" that last a long time.
Shortness of breath
Shortness of breath is a common symptom and is often the most distressing. It is commonly described as: "my breathing requires effort," "I feel out of breath," or "I can't get enough air in."Different terms, however, may be used in different cultures. Typically, the shortness of breath is worse on exertion of a prolonged duration and worsens over time. In the advanced stages, or end stage pulmonary disease, it occurs during rest and may be always present. Shortness of breath is a source of both anxiety and a poor quality of life in those with COPD. Many people with more advanced COPD breathe through pursed lips and this action can improve shortness of breath in some.
Physical activity limitation
COPD often leads to reduction in physical activity, in part due to shortness of breath. In later stages of COPD muscle wasting (cachexia) may occur. Low levels of physical activity are associated with worse outcomes.
The primary cause of COPD is tobacco smoke, with occupational exposure and pollution from indoor fires being significant causes in some countries. Typically, these must occur over several decades before symptoms develop. A person's genetic makeup also affects the risk.
Journal of Clinical Immunology and Allergy