A. Definition and Characteristics

1. Acute Bronchitis [8]
   1. Cough illness lasting <2-3 weeks with inflammation of bronchi
   2. Acute, transient, bronchial hyperresponsiveness
   3. Usually with sputum production, may be copious
2. Chronic Bronchitis - specifically refers to chronic obstructive pulmonary disease
3. Cough persisting >3 weeks is rarely due to a bronchitis type of illness
   1. Over 75% of cough >3 weeks in uncomplicated patients due to the following 3 causes:
   2. Post-nasal drip
   3. Asthma (cough variant type)
   4. Gastroesophageal reflux (GERD)
   5. Cough >3 weeks in patients with underlying medical conditions is considered "complicated"
4. Uncomplicated acute bronchitis - no underlying medical conditions
5. Complicated acute bronchitis [8]
   1. Majority of cases have underlying chronic medical conditions
   2. Progression with fever, tachycardia, tachypnea, frank pneumonia, sepsis may be seen
   3. COPD is most common underlying problem
   4. Congestive heart failure
   5. Immunosuppression - congenital, infection-related, or drug-induced
6. Annual incidence of acute bronchitis is 50-60 per 1000 person-years

B. Etiology of Uncomplicated Acute Bronchitis

1. Viral Upper Repiratory Infections
   1. Influenza A and B - precipitous onset, fever, chills, headache, cough, myalgia
   2. Parainfluenzavirus - usually in autumn; croup in children
   3. Respiratory syncytial virus - family history, bronchiolitis, winter or spring
   4. Coronavirus - can cuase severe symptoms in elderly; high attack rates in military
   5. Adenovirus - clinically similar to influenza, abrupt onset of fever
   6. Rhinoviruses - fever uncommon; generally mild
   7. Incubation period typically <7 days with cold viruses
2. Bacterial Infections
   1. Cause <10% of uncomplicated acute bronchitis
   2. Mycoplasma pneumoniae - incubation 2-3 weeks; gradual onset, cough prominent
   3. Chlamydia pneumoniae - incubation 3 weeks; gradual onset
   4. Bordetella pertussis - incubation 1-3 weeks
   5. S. pneumoniae, Moraxella, and H. influenza do not cause uncomplicated acute bronchitis
3. Eosinophilic Bronchitis
   1. May cause >10% of cases of chronic cough
   2. Presence of eosinophils >5% of non-squamous cells in sputum
   3. Not associated with bronchial hyperresponsiveness

C. Pathophysiology of Uncomplicated Acute Bronchitis

1. Acute Phase
   1. Due to direct inoculation of tracheobronchial epithelium by infectious agent
   2. Cytokine production
   3. Inflammatory cell activation
   4. Fever, myalgias and malaise is variable
   5. Duration is 1-5 days depending on agent, inoculum size and host
2. Protracted Phase
   1. Due to hypersensitivity of epithelial cells lining upper respiratory tract
   2. This is called bronchial hyperresponsiveness
   3. Cough is primary symptom, often with phlegm production
   4. Wheezing is not uncommon
   5. Vagal-mediated airway hyperresponsiveness is most common mechanism
   6. Adrenergic-chlinergic tone imbalance and IgE mediated histamine release may also occur
   7. Pulmonary function test abnormalities may be seen transiently (~40% of cases)
   8. Duration is 1-3 weeks

D. Clinical Presentation and Differential Diagnosis

1. Cough is predominant symptom
2. Phlegm production and/or wheezing may be present
   1. Phlegm is typically clear or yellowish
   2. Green or brown phlegm is typically found with more severe conditions
3. Vital Signs and Physical Exam
   1. Normal or near-normal in uncomplicated acute bronchitis
   2. The presence of any of the following is concerning for pneumonia or other severe condition:
   3. Respiratory rate >24 breaths per minute
   4. Oral body temperature >38°C (>100.5°F)
   5. Presence of rales, egophony or fremitus on chest exam
4. Concerning symptoms or discolored abnormal phlegm should prompt chest radiography (CXR)
5. Cough lasting >3 weeks in adults should prompt examination for Bordetella pertussis
6. In a very small minority of patients, bronchial hyperresponsiveness persists to asthma
7. Goal of initial assessment and diagnosis is to rule out serious illness (pneumonia, others)

E. Treatment [1,8]

1. Antibiotics are generally NOT indicated in uncomplicated acute bronchitis [3,4]
   1. Azithromycin no better than vitamin C (each for 5 days) in acute bronchitis [5]
   2. Delaying treatment with antibiotics in the few cases of bronchitis where they might be beneficial does not lead to prolonged or permanent damage [1]
   3. Treatment of possible or diagnosed influenza considered in first 24-48 hours of symptoms
   4. Azithromycin, clarithromycin, or doxycycline for bacterial causes
2. Physician education of patient is a key driver for patient satisfaction [3]
3. Acute Bronchodilators [4]
   1. Generally recommended only for patients with underlying pulmonary disease [6]
   2. Albuterol or other short-acting ß-agonists: 1-2 puffs as needed up to qid
   3. Long-acting ß-agonists such as salmeterol may reduce nighttime awakening due to cough
   4. Salmeterol is used 1-2 puffs qhs or bid as needed
   5. Inhaled ipratropium bromide may be beneficial in patients with persistent cough after initial acute episode [7]
4. Anti-Tussive Agents
   1. Dextromethorphan
   2. Codeine - much more effective than dextromethorphan
   3. Benefit may be limited to sedating effects, but symptom reductions reported
5. Pain relief - NSAID (such as ibuprofen or naproxen) or acetaminophen
6. Decongestants or anti-cholinergic antihistamines can reduce post-nasal drip
7. Increased humidification is rarely beneficial
8. Short course inhaled or oral glucocorticoids may be beneficial if large inflammatory component and/or wheezing is present

Resources

Aa Gradient

References

1. Wenzel RPO and Fowlder AA. 2006. NEJM. 355(20):2125
2. Irwin RS and Madison JM. 2000. NEJM. 343(23):1716
3. Gonzales R, Bartlett JG, Besser RE, et al. 2001. Ann Intern Med. 134(6):521
4. Snow V, Mottur-Pilson C, Gonzales R. 2001. Ann Intern Med. 134(6):518
5. Evans AT, Husain S, Durairaj L, et al. 2002. Lancet. 359(9318):1648
6. Smucny JJ, Flynn CA, Becker LA, et al. 2001. J Fam Pract. 50:945
7. Holmes PW, Barter CE, Pierce RJ. 1992. Respir Med. 86:425
8. Gonzales R. 2003. JAMA. 289(20):2701