WHAT IS IT?
Chronic bronchitis is continuing inflammation of the breathing passages in the lung. The cause of the inflammation is long-term exposure to airway irritants such as cigarette smoking, occupational dusts and fumes, or allergy-producing materials that are specific to the individual. When the airways of the lung are chronically irritated and inflamed, there is thickening of the walls of the airways, increased mucus production, and decreased ability to clear mucus from the airways. This results in pooling of secretions in the lungs. Airway obstruction follows, setting the stage for increased pulmonary infections.
Chronic bronchitis is sometimes divided into three subcategories. Simple chronic bronchitis is characterized by a chronic productive cough on most days for three months out of the year for two or more years. A small percentage of these individuals will go on to develop chronic obstructive bronchitis, in which irreversible changes in the airways occur. Chronic asthmatic bronchitis is characterized by over-reactive airways that easily go into spasm when irritated, resulting in wheezing. Between ten and twenty-five percent of the adult population are affected by simple chronic bronchitis. It is more common in men than in women. It is not well understood why some of these persons progress to chronic obstructive bronchitis and some do not.
Chronic bronchitis is one of three major lung diseases (bronchitis, emphysema, and asthma) included under the general term
chronic obstructive pulmonary disease (COPD). All three diseases have overlapping symptoms. A person may have more than one chronic process at any given time.
HOW IS IT DIAGNOSED?
History is of a cough that produces sputum on most days for three months out of the year for at least two years.
Physical exam: The individual's respiratory rate and chest expansion may appear normal in early simple bronchitis. The person with chronic obstructive bronchitis may have an elevated respiratory rate, labored respirations, a barrel chest, and a bluish color to the skin (cyanosis). Listening to the chest will likely reveal coarse sounds (rhonchi) that clear with coughing, and possibly wheezing.
Tests: The type and severity of chronic bronchitis is determined by pulmonary function testing. This may be simple airflow measurements (spirometry), along with measurement of blood oxygen saturation (pulse oximetry). It may involve full pulmonary function tests and blood gas measurements, done in a specialized lab. The testing might be done before and after giving a bronchodilator, to determine if any of the airway obstruction is reversible. A chest x-ray may be normal unless the person also has pneumonia or there is severe chronic obstruction.
HOW IS IT TREATED?
A first objective is to eliminate the chronic bronchial irritants that have caused the disease including occupational or environmental exposures to dusts and fumes and cessation of cigarette smoking. The importance of the difficult task of smoking cessation cannot be overemphasized. The individual is also instructed in deep breathing and effective coughing to reduce the numbers of acute infections. A humidifier and, occasionally, postural drainage and percussion can help prevent the pooling of secretions that leads to infections. Individuals with an asthmatic component to their chronic bronchitis will be given bronchodilators orally, inhaled, or both. If the asthmatic component is severe, steroids may be used to break the cycle of airway reactivity. Antibiotics are given during an acute episode of bronchitis, when sputum that is normally white in color changes to yellow or green. Individuals with long-standing chronic obstructive bronchitis and declining lung function may benefit from supplemental oxygen therapy.Immunization against pneumococcal pneumonia and influenza is recommended because of the increased risk of complications and prolonged recovery time if acute respiratory diseases occur.
WHAT MIGHT COMPLICATE IT?
The most common complication of chronic bronchitis is an episode of acute bronchitis or pneumonia. Chronic bronchitis compromises the defense mechanisms of the lung, so the infections can be mild or severe enough to require hospitalization. The most debilitating complications are right heart failure (cor pulmonale) and respiratory failure. Usually, it is an acute infection that precedes an episode of respiratory failure.
Sometimes bronchial secretions collect in the lungs and become thickened. If the individual is unable to cough up these thick secretions, they can totally obstruct the flow of air in a part of the lung. The lung tissue behind the obstruction will then collapse (atelectasis).
PREDICTED OUTCOME
Simple chronic bronchitis has a generally good prognosis. With smoking cessation and vigorous treatment early on, the disease can be reversible. However, recovery time from episodes of acute bronchitis or pneumonia will be longer than normal. Individuals with chronic obstructive bronchitis usually become permanently disabled at some point even with treatment and smoking cessation. Shortness of breath, declining lung function, airflow obstruction, and increasingly frequent complications gradually worsen and can be common.
ALTERNATIVES
Other diagnoses with similarities to chronic bronchitis are asthma,
emphysema,
acute bronchitis,
bronchiectasis, and pneumonia. Tuberculosis, lung cancer, pulmonary embolism, and AIDS-related complex are other possibilities.
APPROPRIATE SPECIALISTS
Pulmonologist and infectious disease specialist.