Acute Bronchitis Lungs : Definition, Diagnosis, Pathophysiology And Treatment
Bronchitis refers to an inflammatory condition of the large elements of the tracheobronchial tree that is usually associated with a generalized respiratory infection. The inflammatory process does not extend to include the alveoli. The disease entity is frequently classified as either acute or chronic.
Acute bronchitis most commonly occurs during the winter months. Cold, damp climates and/or the presence of high concentrations of irritating substances such as air pollution or cigarette smoke may precipitate attacks.
Pathophysiology of Acute Bronchitis :
- Respiratory viruses are by far the most common infectious agents associated with acute bronchitis. The common cold viruses, rhinovirus and coronavirus, and lower respiratory tract pathogens, including influenza virus, adenovirus, and respiratory syncytial virus, account for the majority of cases. Mycoplasma pneumoniae also appears to be a frequent cause of acute bronchitis. Other bacterial causes include Chlamydia pneumoniae and Bordetella pertussis.
- Infection of the trachea and bronchi causes hyperemic and edematous mucous membranes and an increase in bronchial secretions. Destruction of respiratory epithelium can range from mild to extensive and may affect bronchial mucociliary function. In addition, the increase in bronchial secretions, which can become thick and tenacious, further impairs mucociliary activity. Recurrent acute respiratory infections may be associated with increased airway hyperreactivity and possibly the pathogenesis of chronic obstructive lung disease.
- Bronchitis is primarily a self-limiting illness and rarely a cause of death. Acute bronchitis usually begins as an upper respiratory infection. The patient typically has nonspecific complaints such as malaise and headache, coryza, and sore throat.
- Cough is the hallmark of acute bronchitis. It occurs early and will persist despite the resolution of nasal or nasopharyngeal complaints. Frequently, the cough is initially nonproductive but progresses, yielding mucopurulent sputum.
- Chest examination may reveal rhonchi and coarse, moist rales bilaterally. Chest radiographs, when performed, are usually normal.
- Bacterial cultures of expectorated sputum are generally of limited utility because of the inability to avoid normal nasopharyngeal flora by the sampling technique. Viral antigen detection tests can be used when a specific diagnosis is necessary. Cultures or serologic diagnosis of M. pneumoniae and culture or direct fluorescent antibody detection for B. pertussis should be obtained in prolonged or severe cases when epidemiologic considerations would suggest their involvement.
Treatment of Acute Bronchitis :
- The treatment of acute bronchitis is symptomatic and supportive in nature. Reassurance and antipyretics alone are often sufficient. Bedrest and mild analgesic-antipyretic therapy are often helpful in relieving the associated lethargy, malaise, and fever. Aspirin or acetaminophen (650 mg in adults or 10-15 mg/kg per dose in children with a maximum daily adult dose of 4 g and 60 mg/kg for children) or ibuprofen (200 to 800 mg in adults or 10 mg/kg per dose in children with a maximum daily dose of 3.2 g for adults and 40 mg/kg for children) is administered every 4 to 6 hours.
- Patients should be encouraged to drink fluids to prevent dehydration and possibly decrease the viscosity of respiratory secretions.
- In children, aspirin should be avoided and acetaminophen used as the preferred agent because of the possible association between aspirin use and the development of Reye’s syndrome.
- Mist therapy and/or the use of a vaporizer may further promote the thinning and loosening of respiratory secretions.
- Persistent, mild cough, which may be bothersome, may be treated with dextromethorphan; more severe coughs may require intermittent codeine or other similar agents.
- Routine use of antibiotics in the treatment of acute bronchitis is discouraged; however, in patients who exhibit persistent fever or respiratory symptomatology for more than 4 to 6 days, the possibility of a concurrent bacterial infection should be suspected.
- When possible, antibiotic therapy is directed toward anticipated respiratory pathogen(s) (i.e., Streptococcus pneumoniae, Haemophilus influenzae) and/or those demonstrating a predominant growth upon throat culture.
- M. pneumoniae, if suspected by history or positive cold agglutinins (titers greater than or equal to 1:32) or if confirmed by culture or serology, may be treated with erythromycin or its analogs (e.g., clarithromycin or azithromycin). Also, a fluoroquinolone with activity against these pathogens (gatifloxacin or increased dose levofloxacin) may be used in adults.
- During known epidemics involving the influenza A virus, amantadine or rimantadine may be effective in minimizing associated symptomatology if administered early in the course of the disease.
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