Chronic obstructive pulmonary disease(COPD), also known as chronic obstructive lung disease (COLD), and chronic obstructive airway disease(COAD), among others, is a type of obstructive lung disease characterized by chronically poor airflow. It typically worsens over time. The main symptoms include shortness of breath, cough, and sputum production. Most people with chronic bronchitis have COPD.
Tobacco smoking is the most common cause of COPD, with a number of other factors such as air pollution and genetics playing a smaller role. In the developing world, one of the common sources of air pollution is from poorly vented cooking and heating 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 known as emphysema. The diagnosis is based on poor airflow as measured by lung function tests. In contrast to asthma, the airflow reduction does not improve significantly with the administration of medication.
COPD can be prevented by reducing exposure to the known causes. This includes efforts to decrease rates of smoking and to improve indoor and outdoor air quality. COPD treatments include: quitting smoking, vaccinations, 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 and hospitalization may be needed.
Worldwide, COPD affects 329 million people or nearly 5% of the population. In 2012, it ranked as the third-leading cause of death, killing over 3 million people. The number of deaths is projected to increase due to higher smoking rates and an aging population in many countries. It resulted in an estimated economic cost of $2.1 trillion in 2010.
The primary cause of COPD is tobacco smoke, with occupational exposure and pollution from indoor fires being significant causes in some countries. Typically these exposures must occur over several decades before symptoms develop. A person’s genetic makeup also affects the risk.
The primary risk factor for COPD globally is tobacco smoking. Of those who smoke about 20% will get COPD, and of those who are lifelong smokers about half will get COPD. In the United States and United Kingdom, of those with COPD, 80-95% are either current smokers or previously smoked. The likelihood of developing COPD increases with the total smoke exposure. Additionally, women are more susceptible to the harmful effects of smoke than men. In non-smokers, secondhand smoke is the cause of about 20% of cases. Other types of smoke, such as marijuana, cigar, and water pipe smoke, also confer a risk. Women who smoke during pregnancy may increase the risk of COPD in their child.
Poorly ventilated cooking fires, often fueled by coal or biomass fuels such as wood and animal dung, lead to indoor air pollution and are one of the most common causes of COPD in developing countries. These fires are a method of cooking and heating for nearly 3 billion people with their health effects being greater among women due to more exposure. They are used as the main source of energy in 80% of homes in India, China and sub-Saharan Africa.
People who live in large cities have a higher rate of COPD compared to people who live in rural areas. While urban air pollution is a contributing factor in exacerbations, its overall role as a cause of COPD is unclear. Areas with poor outdoor air quality, including that from exhaust gas, generally have higher rates of COPD. The overall effect in relation to smoking, however, is believed to be small.
Intense and prolonged exposure to workplace dusts, chemicals and fumes increase the risk of COPD in both smokers and nonsmokers. Workplace exposures are believed to be the cause in 1020% of cases. In the United States they are believed to be related to more than 30% of cases among those who have never smoked and probably represent a greater risk in countries without sufficient regulations.
A number of industries and sources have been implicated, including high levels of dust in coal mining, gold mining, and the cotton textile industry, occupations involving cadmium and isocyanates, and fumes from welding. Working in agriculture is also a risk. In some professions the risks have been estimated as equivalent to that of half to two packs of cigarettes a day. Silica dust exposure can also lead to COPD, with the risk unrelated to that for silicosis. The negative effects of dust exposure and cigarette smoke exposure appear to be additive or possibly more than additive.
Genetics play a role in the development of COPD. It is more common among relatives of those with COPD who smoke than unrelated smokers. Currently, the only clearly inherited risk factor is alpha 1-antitrypsin deficiency (AAT). This risk is particularly high if someone deficient in alpha 1-antitrypsin also smokes. It is responsible for about 15% of cases and the condition is present in about 34 in 10,000 people. Other genetic factors are being investigated, of which there are likely to be many.
An acute exacerbation (a sudden worsening of symptoms) is commonly triggered by infection or environmental pollutants, or sometimes by other factors such as improper use of medications.
Sign And Symptoms
The most common symptoms of COPD are sputum production, shortness of breath and a productive cough. These symptoms are present for a prolonged period of time and typically worsen over time. It is unclear if 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 usually the first symptom to occur. When it exists for more than three months a year for more than two years, in combination with sputum production and without another explanation, there is by definition chronic bronchitis. This condition can occur before COPD fully develops. The amount of sputum produced can change over hours to days. In some cases the cough may not be present or only occurs 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. Vigorous coughing may lead to rib fractures or 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 often the symptom that bothers people the most. 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 it occurs during rest and may be always present. It 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.
An acute exacerbation of COPD is defined as increased shortness of breath, increased sputum production, a change in the color of the sputum from clear to green or yellow, or an increase in cough in someone with COPD. This may present with signs of increased work of breathing such as fast breathing, a fast heart rate, sweating, active use of muscles in the neck, a bluish tinge to the skin, and confusion or combative behavior in very severe exacerbations. Crackles may also be heard over the lungs on examination with a stethoscope.