Chronic Bronchitis : Diagnosis, Pathophysiology, Treatment
Chronic bronchitis is a nonspecific disease that primarily affects adults.
- Chronic bronchitis is a result of several contributing factors, including cigarette smoking; exposure to occupational dusts, fumes, and environmental pollution; and bacterial (and possibly viral) infection.
- In chronic bronchitis, the bronchial wall is thickened and the number of mucus-secreting goblet cells in the surface epithelium of both larger and smaller bronchi is markedly increased. Hypertrophy of the mucus glands and dilatation of the mucus gland ducts are also observed. As a result of these changes, patients with chronic bronchitis have substantially more mucus in their peripheral airways, further impairing normal lung defenses and causing mucus plugging of the smaller airways.
- Continued progression of this pathology can result in residual scarring of small bronchi, augmenting airway obstruction and the weakening of bronchial walls.
- The hallmark of chronic bronchitis is cough that may range from a mild â€œsmoker’sâ€ cough to severe incessant coughing productive of purulent sputum. Expectoration of the largest quantity of sputum usually occurs upon arising in the morning, although many patients expectorate sputum throughout the day. The expectorated sputum is usually tenacious and can vary in color from white to yellow-green.
- By definition, any patient who reports coughing up sputum on most days for at least three consecutive months each year for two consecutive years suffers from chronic bronchitis.
- With the exception of pulmonary findings, the physical examination of patients with mild to moderate chronic bronchitis is usually unremarkable.
- An increased number of polymorphonuclear granulocytes in sputum often suggests continual bronchial irritation, whereas an increased number of eosinophils may suggest an allergic component. The most common bacterial isolates (expressed in percentages of total cultures) identified from sputum culture in patients experiencing an acute exacerbation of chronic bronchitis.
- A complete occupational/environmental history for the determination of exposure to noxious, irritating gases, as well as cigarette smoking, must be assessed. Attempts must be made to reduce exposure to bronchial irritants.
- Humidification of inspired air may promote the hydration (liquefaction) of tenacious secretions, allowing for more effective sputum production. The use of mucolytic aerosols (e.g., N-acetylcysteine; deoxyribonuclease [DNase]) is of questionable therapeutic value.
- Postural drainage may assist in promoting clearance of pulmonary secretions
- Oral or aerosolized bronchodilators (e.g., albuterol aerosol) may be of benefit to some patients during acute pulmonary exacerbations. For patients who consistently demonstrate limitations in airflow, a therapeutic change of bronchodilators should be considered.
- The use of antimicrobials has been controversial, although antibiotics are an important component of treatment. Agents should be selected that are effective against likely pathogens, have the lowest risk of drug interactions, and can be administered in a manner that promotes compliance.
- Selection of antibiotics should consider that up to 30% to 40% of H. influenzae and 95% of M. pneumoniae are Î²-lactamase producers, and up to 30% of S. pneumoniae are at least moderately penicillin resistant.
- Antibiotics commonly used in the treatment of these patients and their respective adult starting doses. Duration of symptom-free periods may be enhanced by antibiotic regimens using the upper limit of the recommended daily dose for 10 to 14 days.
- Ampicillin is often considered the drug of choice for the treatment of acute exacerbations of chronic bronchitis. Unfortunately, the need for multiple repeat daily doses (4 times daily) and the increasing incidence of penicillin-resistant Î²-lactamase-producing strains of bacteria have limited the usefulness of this safe and cost-effective antibiotic.
- The value of macrolides when Mycoplasma is involved is unquestioned. Azithromycin should be considered as the macrolide of choice for Mycoplasma.
- The fluoroquinolones are effective alternative agents for adults, particularly when gram-negative pathogens are involved, or for more severely ill patients. Many S. pneumoniae are resistant to older fluoroquinolones such as ciprofloxacin, necessitating the use of newer agents such as gatifloxacin.
- In patients whose history suggests recurrent exacerbations of their disease that might be attributable to certain specific events (i.e., seasonal, winter months), a trial of prophylactic antibiotics might be beneficial. If no clinical improvement is noted over an appropriate period (e.g., 2 to 3 months per year for 2 to 3 years), prophylactic therapy could be discontinued.