- Harrison’s Principles of Internal Medicine 17th edition
- Ján Tkác, S. F. Paul Man and Don D. Sin. Systemic consequences of COPD. Ther Adv Respir Dis (2007) 1(1) 47–59.
What is Chronic Obstructive Pulmonary Disease?
Chronic obstructive pulmonary disease (COPD) is a group of respiratory tract disorders where there is obstruction to airflow, which is not completely reversible and is usually progressive.
Air normally enters the respiratory system via the nose and mouth while breathing. The muscles of the chest and the diaphragm (a muscular partition between the chest and the abdomen) aid in this process. The inhaled air passes through the throat and reaches the wind pipe or trachea. The trachea divides into two branches in the chest, the left and right bronchi. Each bronchus further divides and re-divides into smaller branches, finally forming very small branches called the bronchioles. The bronchioles end in small air sacs called the alveoli in the lungs. The alveoli are elastic, enabling them to expand and contract with breathing. A number of small blood vessels lie close to the alveoli. The air from the trachea passes through the bronchi and bronchioles and reaches the alveoli. Oxygen from the air diffuses through the alveolar wall into the blood and carbon dioxide from the blood diffuses into the alveoli. Thus exchange of gases takes place at this level. Carbon dioxide then is thrown out through the bronchi, trachea and nose and mouth while breathing out.
COPD includes respiratory tract disorders which cause obstruction to airflow. These are:
- Emphysema: Emphysema is a condition where the lung sacs or alveoli lose their elasticity and are enlarged
- Chronic Bronchitis: Chronic bronchitis is a condition where the bronchi are inflamed, resulting in cough and phlegm (thick mucus secretion from the respiratory tract) production
- Small airway disease: Small airway disease is a condition where the small airways or bronchioles are narrowed
COPD is the fourth leading cause of death in the United States. Cigarette smoking is the most important risk factor for COPD. COPD is more common in males since the number of male smokers is higher than female smokers. However, the number of female cases is on the rise due to an increase in the number of female smokers. Quitting smoking especially before the disease has severely affected the patient may help to reduce the damage. Some cases may be caused due to lack of an enzyme called alpha-1 antitrypsin.
The patient suffers from symptoms of cough, breathlessness and sputum production. Breathlessness may initially be experienced when the patient physically exerts himself, but later it may appear even at rest. Attacks of COPD may occur more and more frequently as the disease progresses.
The patient is diagnosed using tests called pulmonary function tests. Other tests like measurement of blood gases, chest x-ray, CT scan and measurement of alpha-1 antitrypsin levels are also used in diagnosing COPD.
The patient is treated using drugs that widen the air passages like tiotropium and salmeterol, other drugs like corticosteroids and theophylline, and oxygen. Surgery including lung transplantation may be required in some cases. The patient should be strongly advised to quit smoking.