Chronic Obstructive Pulmonary Disease
DefinitionA group of lung diseases characterized by limited airflow through the airways with variable degrees of air sack enlargement and lung tissue destruction. The diseases emphysema and chronic bronchitis are the most common forms of chronic obstructive pulmonary disease.
Alternative names
COPD; Chronic obstructive airway disease; Chronic respiratory insufficiency
Causes, Incidences and Risk Factors
The leading cause of COPD is smoking, which can lead to the two most common forms of this disease, emphysema and chronic bronchitis. Prolonged tobacco use causes lung inflammation and variable degrees of air sack (alveoli) destruction. This leads to inflamed and narrowed airways (chronic bronchitis); or permanently enlarged air sacks of the lung with reduced lung elasticity (emphysema). 15% of long-term smokers will develop COPD. Rarely, an enzyme deficiency called alpha-1 anti-trypsin deficiency can cause emphysema in non-smokers.
After tobacco-use, other risk factors for COPD are passive smoking (exposure of non-smokers to cigarette smoke from others), male gender, and working in a polluted environment.
Prevention
Avoidance of smoking prevents COPD. Early recognition and treatment of small airway disease in people who smoke, combined with smoking cessation, may prevent progression of the disease.
Symptoms
Shortness of breath (dyspnea) persisting for months to years
Wheezing
Decreased exercise tolerance
Cough with or without phlegm
Signs and Tests
An examination often reveals increased work involved in breathing: nasal flaring may be evident during air intake, and the lips may be pursed (the shape lips make when you whistle) while exhaling. During a flare of disease, chest inspection reveals contraction of the muscles between the ribs (intercostal retraction) and the use of accessory breathing muscles. The respiratory rate (amount of breaths per minute) may be elevated, and wheezing may be heard through a stethoscope. A chest X-ray can show an over-expanded lung (hyperinflation) and a chest CAT scan (CT) may show emphysema. A sample of blood taken from an artery (arterial blood gas) can show low levels of oxygen (hypoxemia) and high levels of carbon dioxide (respiratory acidosis). Pulmonary function tests show decreased airflow rates while exhaling and over-expanded lungs.
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