The COPD definition that is most meaningful is one that explains what it is and which discusses the COPD pathophysiology.
COPD stands for chronic obstructive pulmonary disease. Another term for it is COLD which stands for chronic obstructive lung disease. The pathophysiology of COPD is the processes within the body related to the disease and their effect on normal lung function. Those effects result in the signs and symptoms of the disease.
Chronic obstructive lung disease is a group of conditions that causes obstruction of airflow through the tubules of the lungs over a prolonged period of time. That obstruction may be continuous with varying degrees of severity at changing intervals. It might also be intermittent.
In the broad technical sense the COPD definition includes a number of conditions that cause chronic airway obstruction. They are chronic bronchitis, emphysema, asthma and bronchiectasis. Diseases that cause short-term airway obstruction, such as acute bronchitis, are not included.
In a more practical sense, the COPD definition is more restrictive. It takes into account the following: 1) Medication does not completely reverse the airway obstruction. 2) Inhaled irritants (usually those in tobacco smoke) are the cause of the obstruction. Accordingly, asthma and bronchiectasis are not forms of chronic obstructive pulmonary disease, but are separate diseases. Thus, chronic obstructive pulmonary disease is emphysema, chronic bronchitis, or a combination of the two. Most sufferers have mixed disease and therefore may have varying signs and symptoms of both.
The practical definition of COPD is the one recognized by the health care community. Not only do doctors and other healthcare providers mean emphysema or chronic bronchitis when they use the term. Health insurance companies do also. Additionally, the ICD 10 coding system lists emphysema and chronic bronchitis as forms of chronic obstructive lung disease but lists asthma and bronchiectasis as separate conditions.
Regardless of its form, the pathophysiology of COPD involves chronic inflammation and changes in the structures and functions of the lung. The result is impairment of gas exchange between the atmosphere and the lungs.
In the case of chronic bronchitis the medium-sized and small air tubes are inflamed and swollen. Goblet cells produce an increased amount of mucus. There is also decreased clearance of the mucus because of damage to the hair cells within the tubes which normally help expel it. Because of all these conditions, there is restricted airflow in and out of the lungs which causes wheezing and shortness of breath. Sufferers oftentimes have a bluish complexion due to low oxygen levels in tissues. They are also many times overweight and swollen. Thus, they sometimes match the descriptor, blue bloater.
The pathophysiology of COPD is quite different in the case of emphysema. There is still chronic inflammation and damage, but primarily in the structures just past the end of the small air tubes where gas exchange occurs. The term for those structures is alveoli. The immune system’s response to noxious particles causes destruction and enlargement of those air exchange structures. In addition it results in destruction of elastic tissue and other supporting tissue within the lungs. The end result is air trapping. As a result, there is greater difficulty exhaling air than inhaling air. Emphysema sufferers are oftentimes underweight due to the increased work of breathing. They also tend to have pinkish complexions. Therefore, the coined descriptor, pink puffer is oftentimes applicable.
Familiarity with the COPD definition and the pathophysiology of COPD is important because the condition is the third leading cause of death in the United States. More importantly, because of its link to cigarette smoking, it is usually preventable.