Description

• Acute bronchitis is a lower respiratory tract infection that causes reversible bronchial inflammation, involving the large airways, without evidence of pneumonia, that occurs in the absence of chronic obstructive lung disease.
• Cough, the predominant symptom, may last as long as 3 weeks (1).
• Generally self-limited, with complete healing and full return of function (1)
• Most infections are viral if no underlying cardiopulmonary disease is present (1).
• Synonym(s): tracheobronchitis

Geriatric Considerations
Can be serious, particularly if part of influenza, with underlying COPD or CHF

Pediatric Considerations

• Usually occurs in association with other conditions of upper and lower respiratory tract (Trachea is usually involved.)
• If repeated attacks occur, child should be evaluated for anomalies of the respiratory tract, immune deficiencies, or for asthma.
• Acute bronchitis caused by RSV may be fatal.
• Antitussive medication is not indicated in patients aged <6 years (1).

Epidemiology

• Predominant age: all ages
• Predominant gender: male = female

Incidence
It accounts for approximately 10% of ambulatory care visits in the United States or 100 million visits per year. The incidence of acute bronchitis is highest in late fall and winter when transmission of respiratory viruses peaks (1),(2).

Etiology and Pathophysiology

• Viruses are the most commonly identified pathogens in patients with acute bronchitis (about 60%). The most common viral causes of acute bronchitis include the following (1):
  • Influenza A and B
  • Parainfluenza
  • Coronavirus types 1 to 3
  • Rhinoviruses
  • Respiratory syncytial virus
  • Human metapneumovirus
• Bacteria account for 6% of cases.
• The bacteria most commonly associated with acute bronchitis include Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Bordetella pertussis.
• Approximately 10% of patients presenting with a cough lasting at least 2 weeks have evidence of B. pertussis infection.
• Possible fungal infections
• Chemical irritants
• Acute bronchitis causes an injury to the epithelial surfaces, resulting in an increase in mucus production and thickening of the bronchiole wall.

Genetics
No known genetic pattern

Risk Factors

• Infants
• Elderly
• Air pollutants
• Smoking
• Secondhand smoke
• Environmental changes
• Chronic bronchopulmonary diseases
• Chronic sinusitis
• Tracheostomy or endobronchial intubation
• Bronchopulmonary allergy
• Hypertrophied tonsils and adenoids in children
• Immunosuppression
  • Immunoglobulin deficiency
  • HIV infection
  • Alcoholism
• Gastroesophageal reflux disease (GERD)

General Prevention

• Avoid smoking and secondhand smoke.
• Control underlying risk factors (i.e., asthma, sinusitis, and reflux).
• Avoid exposure, especially daycare.
• Pneumovax, influenza immunization

Commonly Associated Conditions

• Allergic rhinitis
• Sinusitis
• Pharyngitis
• Epiglottitis (rare but can be rapidly fatal)
• Coryza
• Croup
• Influenza
• Pneumonia
• Asthma
• COPD/emphysema
• GERD