Emphysema is a form of chronic obstructive pulmonary disease; it is over inflation of structures in the lungs. Examination of the lung of someone with emphysema reveals distinct abnormalities. The tiny air sacs are gone. The delicate alveolar airexchange mechanism has been replaced by large, limp bags of tissue (blebs) or, in severe cases, fluid-filled cyst-like structures. Also, the blood supply to these tissues is reduced or entirely absent so that the surface area formerly available for exchange of carbon dioxide and oxygen is greatly diminished.
With fewer channels through which blood can reach the lungs, the flow resistance rises, raising the pulmonary artery pressure and increasing the load on the heart. The majority of emphysema cases result from bronchial irritation. Mucus builds up in small air passages which are narrowed further by spasms of the wall muscles, thus creating a valve effect. Air can enter the lungs with deep inhalations, but then coughing and forced exhalation collapse the airway so that the air cannot be expelled.
Alveolar sacs become overstretched and their membrane walls rupture. If this process continues over a period of years, it gradually destroys the lung surface through which gases are exchanged. Because new tissue cannot grow in the area of destruction, the process is irreversible. The most successful treatment has been clearing of the airway secretions to prevent progressive deterioration and air entrapment.
This is accomplished by thinning the secretions for easier removal, avoiding irritants, promptly treating infections, strengthening the breathing muscles and improving general body tone through exercise and adequate nutrition, and using medications judiciously to eliminate bronchial muscle spasms and keep the airway open. A rare variety found in less than one percent of all patients is known as congenital or hereditary emphysema.
The condition stems from a genetic defect in the elastic tissue that forms the walls of the alveoli. Victims are found to have an enzyme (alpha one antitrypsin) deficiency in their peripheral blood. Congenital emphysema may appear in the very young with no history of bronchial irritation, infection, asthma, or other airway irritation. The usual treatment has no effect. Although an in creased risk of infection is common, the airway collapse and air trapping normally associated with emphysema does not occur.