The most meaningful answer to the question – what is COPD – is not a mere definition. It includes the meaning of the acronym; a description of the pathology; data pertaining to prognosis and mortality; the different types and stages of the disease; its signs and symptoms; what causes it; stages of the disease; the diagnosis of it; and the treatment of it.
What Does COPD Stand For?
COPD is an acronym that stands for chronic obstructive pulmonary disease. It is synonymous with chronic obstructive lung disease or COLD.
It is a group of lung conditions which causes obstructed airflow in and out of the lungs over a prolonged period of time. An abnormal inflammatory response of the lungs to inhaled irritants is the basis of its development. Symptoms due to the obstruction can be continuous or continual depending on the patient and the stage of the disease.
COPD Prognosis and Mortality Data
COPD is the third leading cause of death due to disease in the United States. It ranks behind only heart disease which is the leading cause of death and cancer which is second on the list. More importantly, the death rates for heart disease, strokes and accidents declined by 52%, 63.1%, and 41% respectively from 1970 through 2002, but increased by 102.8% for COPD during that same time frame. Death rates for COPD declined somewhat for men between 1999 and 2010 but there was no significant change for women.
Lung function begins to decline around the age of 50. Consequently the death rate from COPD increases by 35% with each increased decade of life. The rate and degree of decline in lung function increase in individuals who smoke if they are susceptible to tobacco smoke. That susceptibility begins to take its toll after the amount of smoking has equal or exceeded 20 pack years. Pack years is a term derived from multiplying the number of packs per day by the number of years one has smoked.
The good news according to research is that only 30% of cigarette smokers are susceptible to tobacco smoke and end up developing COPD. That means 70% of people who smoke don’t develop chronic obstructive pulmonary disease. The bad news though is they are still more susceptible to the other harmful effects of smoking which include the development of cancer and heart disease.
Types of COPD
In a broad and technical sense, chronic bronchitis, emphysema, asthma and bronchiectasis are all forms of COPD. But in a practical sense COPD is chronic bronchitis, emphysema, or a mixture of the two. When doctors and other healthcare providers use the term COPD, they mean chronic bronchitis and emphysema, not asthma or bronchiectasis. This more practical definition of COPD takes into account the fact that it is usually progressive and the airway obstruction is not fully reversible.
What is Chronic Bronchitis?
Chronic bronchitis is a state of chronic inflammation and swelling of the airways of the lungs. It is also a state of increased production of mucus, which along with the inflammation and swelling causes the obstruction of air flow within the airways of the lungs. The limited airflow during breathing interferes with the body’s normal process of gas exchange in the lungs. It is most commonly the result of cigarette smoking.
What is Emphysema?
Emphysema is the loss of lung air sacs, enlargement of remaining sacs, loss of lung elastic tissue and a reduction in the number of pulmonary capillaries. The changes occur in response to chronic inflammation. The loss of elastic tissue causes problems with exhalation for two reasons. The primary reason is that healthy lung elastic recoil is one of the main driving forces of exhalation. The other reason is that elastic tissue around and between alveoli and bronchioles recoil when adjacent structures stretch them while closing, thus preventing them from collapsing during exhalation. Disturbances of both mechanisms cause air trapping in the lungs because of incomplete exhaling of air.
Signs and Symptoms of COPD
Despite the fact that chronic bronchitis and emphysema are two distinct forms of chronic obstructive pulmonary disease, most individuals with it have a mixture of both. Therefore they show and have varying signs and symptoms of both diseases.
The common symptom that individuals with both forms of the disease experience is shortness of breath (dyspnea). They also will have an increased rate of breathing (tachypnea) when short of breath. Both forms are prone to COPD exacerbation which is an acute worsening of symptoms oftentimes requiring treatment in a hospital.
Chronic bronchitis symptoms and signs
Because the inflammation and swelling of the airways causes narrowing of the passages, individuals with chronic bronchitis oftentimes wheeze. Because of increased mucus production by goblet cells in the lungs, a chronic productive cough is a common symptom. Bluish discoloration of the skin, mucous membranes or nail beds (cyanosis) is common because of decreased oxygenation resulting from diminished airflow into the lungs. Individuals with chronic bronchitis are more prone to develop pulmonary hypertension and cor pulmonale than individuals with emphysema. Partially because of the fluid retention which occurs with cor pulmonale many with chronic bronchitis are overweight. When overweight swollen and cyanotic they have an appearance consistent with the descriptor, blue bloater.
Emphysema symptoms and signs
Emphysema sufferers have to work harder to breathe due to the difficulties they experience exhaling. That increased work includes generating higher chest cavity pressures. They use breathing muscles not normally utilized and exert more effort while using the muscles normally involved in breathing. Because of the tendency for airways to collapse in the face of the increased chest cavity pressures, they oftentimes exhale through pursed lips to prevent or minimize airway collapse. They also exhibit prolonged expiration because of obstruction to outward airflow.
Sufferers tend to be leaner or underweight, especially in comparison to their chronic bronchitis counterparts because of the increase energy expended while breathing. They oftentimes have a pinkish complexion as opposed to the bluish one of chronic bronchitics. That is because emphysema sufferers don’t commonly have a problem with blood flow to the lungs in comparison to chronic bronchitis sufferers who are more prone to cor pulmonale. Additionally, significant ventilation/perfusion mismatch is less common in emphysema until the disease becomes very advanced. The reason is the loss of pulmonary capillaries tends to match the loss of alveoli. Pink puffer is a descriptor for describing them because of their pink complexion and labored breathing.
A person with emphysema might wheeze but not to the same degree or as often as someone with chronic bronchitis. The physical sign most commonly heard with a stethoscope is diminished breath sounds. Other physical signs which help distinguish emphysema from chronic bronchitis are a barrel shaped chest and distant (soft) heart sounds.
By and large, the most common cause of COPD is cigarette smoking. Other established causes are occupational exposure to irritants, a genetic predisposition, and air pollution. Other possible but not clearly proven causes are exposure to secondhand smoke, alcohol consumption and poverty.
The genetic predisposition is for emphysema. It warrants special attention and understanding because it is more frequent than previously suspected. Additionally its presence can explain cases of emphysema in individuals who have never smoked. That condition is alpha-1 antitrypsin deficiency.
The body’s immune system normally produces a protein known as neutrophil elastase. It helps destroy harmful bacteria in the lungs and dispose of aging lung cells. The liver produces a substance known as alpha-1 antitrypsin which neutralizes the neutrophil elastase to keep it from going amok after it performs its primary job. When the liver does not produce the protective protein in sufficient quantities or not at all because of a genetic defect, neutrophil elastase causes the lung tissue damage of emphysema described above. The degree of alpha-1 antitrypsin deficiency depends on whether the defect is due to a gene from one or both parents. A screening blood test can detect the condition.
A history of cigarette smoking along with signs and symptoms of chronic bronchitis, emphysema or a combination of the two is oftentimes sufficient to diagnose COPD. A chest x-ray can sometimes differentiate between chronic bronchitis and emphysema. With emphysema it might show hyperinflation (increased amounts of air) in the lungs with flattening of the diaphragms.” It might show a bulla or bullae in the case of bullous emphysema. With chronic bronchitis a chest x-ray might show increased markings.
Spirometry is the gold standard for making and confirming the diagnosis. Additionally, spirometry can establish the severity of the disease and determine the degree of reversibility of airway obstruction.
GOLD established a system for classifying COPD. GOLD stands for Global initiative for Chronic Obstructive Lung Disease. The system consists of stages. Disease severity defines the stage. FEV1 and FEV1/FVC are the staging criteria. The criteria and staging are as follows.
|Stage I||Mild||FEV1 ≥ 80% of normal||FEV1/FVC<0.70|
|Stage II||Moderate||FEV1 50-79% of normal||FEV1/FVC<0.70|
|Stage III||Severe||FEV1 30-49% of normal||FEV1/FVC<0.70|
|Stage IV||Very severe||FEV1 less than 30% of normal, or less than 50% of normal with chronic respiratory failure present||FEV1/FVC<0.70|
Treatment of COPD
Because of the strong link between COPD and its progression to smoking, cessation is one of the most important forms of treatment. Because it is often unsuccessful and not sufficient alone, other forms of treatment are usually necessary.
Bronchodilators and anti-inflammatory agents are the cornerstone of pharmacologic treatment of COPD. There are long acting and short acting bronchodilators. In addition to beta agonists, medications that block the actions of the parasympathetic nervous system in the lungs also cause dilation of the airways. These agents bear the name anticholinergics because they block receptors that respond to the neurotransmitter acetylcholine. Most bronchodilators require inhalation, but some are for oral use.
The main anti-inflammatory medicine for treating COPD is corticosteroids. They are available in oral and inhaled forms. There are also two newer types of drugs that block other aspects of the immune system response involved in inflammation. They are the leukotriene modifiers and DPE4 inhibitors.
Many patients with COPD require oxygen if their tissue levels are too low. The physician guideline for prescribing oxygen treatment is if the O2 saturation via pulse oximeter is 88% or less, whether it is at rest or during activity.
An injectable protein concentrate replacement is available for individuals with alpha-1 antitrypsin deficiency. The FDA has approved three products for use. But there have been no controlled studies to prove that it improves survival or slows the rate of emphysema progression.