Emphysema Health Article

Definition

Emphysema is a chronic respiratory disease in which overinflation of the alveoli or air sacs causes a decrease in respiratory function and often dyspnea.

Description

Emphysema is the most common cause of death from respiratory disease in the United States, and is the fourth most common cause of death overall. There are1.8 million Americans with the disease, which ranks fifteenth among chronic conditions that cause limitations of activity. Around 44% of those with emphysema state that their activities of daily living have been affected by the disease.

Normally functioning lungs are elastic, efficiently expanding and recoiling as air passes freely through the bronchus to the alveoli, where oxygen is moved into the blood and carbon dioxide is filtered out. When a person inhales cigarette smoke, his or her immune system responds by releasing substances that are meant to defend the lungs against the smoke. These substances can also attack the cells of the lungs. Normally, the body inhibits such action by releasing other substances. In smokers and those with the inherited emphysema defect, however, no such prevention occurs, and the lung tissue is damaged in such a way that it loses its elasticity. The small passageways leading to the alveoli collapse, trapping air within the alveoli. The alveoli, unable to recoil efficiently and move the air out, overexpand and rupture. The smaller areas of alveoli destruction are known as blebs and the larger ones are called bullae. As the disease progresses coughing and dyspnea occur. In the later stages the lungs cannot supply sufficient oxygen to the blood. Emphysema often occurs with other respiratory diseases, particularly chronic bronchitis. These two diseases are often referred to as one—chronic obstructive pulmonary disease (COPD).

Emphysema is most common among people aged 50 years and older. Those with inherited emphysema may experience the onset as early as their 30s or 40s. Men are more likely than women to develop emphysema, but female cases are increasing as the number of female smokers rises.

Causes and symptoms

Heavy cigarette smoking causes about 80–90% of all emphysema cases. However, a few cases are the result of an inherited deficiency of alpha-1-antitrypsin (AAT). The number of Americans with this deficiency is relatively small, probably no greater than 70,000. Pipe, cigar, and marijuana smoking can also damage the lungs. While a person may be less likely to inhale cigar and pipe smoke, these types of smoke can also impair lung function. Marijuana smoke is even more damaging because it is inhaled deeply and held in the lungs longer by the smoker.

The symptoms of emphysema develop gradually over many years. It is a common occurrence for many emphysema patients to have lost 50–70% of their functional lung tissue before they become aware that something is wrong. Dyspnea, a chronic mild cough (which may be productive of large amounts of dark, thick sputum, and often dismissed as "smoker's cough"), and sometimes weight loss are associated with emphysema. Initially, a patient may notice shortness of breath only when he or she is exercising. However, as the disease progresses, it will occur during less exertion, and ultimately with no exertion at all. Emphysema patients may also develop an enlarged, or "barrel," chest. Other symptoms may include skipped breaths, insomnia, morning headaches, nasal flaring, increased difficulties breathing while lying down, chronic fatigue, and swelling of the feet, ankles, or legs. Those with chronic emphysema are at risk for other complications resulting from weakened lung function. These include pneumonia, pulmonary hypertension, cor pulmonale, and chronic respiratory failure.

Diagnosis

A history of heavy smoking alone is not enough for a physician to differentiate emphysema from other respiratory diseases. A physician will combine information on symptoms, medical history, physical examination, lung function tests, and chest x ray results to make a diagnosis of emphysema. One of the first clues may be a hollow sound heard through a stethoscope as the patient's chest is being tapped. The hollow sound is the result of the enlargement or rupture of the lungs' alveoli.

A variety of pulmonary function tests may be ordered. In the early stages of emphysema, the only result may be dysfunction of the small airways. Patients with emphysema may show an increase in the total amount of air that is in the lungs (total lung capacity), but a decrease in vital capacity. With severe emphysema, vital capacity is substantially below normal. Spirometry, a procedure that measures respiratory gases and resulting pulmonary function, aids in the diagnosis of emphysema.

A chest x ray is often ordered to aid in the diagnosis of emphysema, though patients in the early stages of the disease may have normal findings. Abnormal findings on the chest x ray include excessive inflation of the lungs and an abnormally increased chest diameter. The diaphragm may appear depressed or flattened. In addition, patients with advanced emphysema may show an enlargement of the heart. The physician may observe blisters in the lungs and bulging of the accessory muscles of the respiratory system. Late in the disease an EKG will show signs of right ventricular failure in the heart and increased hemoglobin due to lower oxygen in the patient's blood.

Other tests that may be performed include peak flow measurements, arterial blood gases, and pulse oximetry.