Asma Y Epoc

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clinical practice

Acute Bronchitis
Richard P. Wenzel, M.D., and Alpha A. Fowler III, M.D.
This Journal feature begins with a case vignette highlighting a common clinical problem. Evidence supporting various strategies is then presented, followed by a review of formal guidelines, when they exist. The article ends with theauthors’ clinical recommendations.

A 40-year-old man with no underlying lung disease has a 7-day history of mild shortness of breath with exertion, as well as cough that is now productive of purulent sputum. He reports no paroxysms of cough and no contact with ill persons in his community. He does not appear to be in distress. His temperature is 37°C, his pulse 84 beats per minute, and hisrespiratory rate 17 breaths per minute. On auscultation of the lungs, no rales are heard; scattered wheezes are heard in the lung bases. How should he be evaluated and treated?

The Cl inic a l Probl e m
Acute bronchitis is a clinical term implying a self-limited inflammation of the large airways of the lung that is characterized by cough without pneumonia. The disorder affects approximately 5% of adultsannually,1,2 with a higher incidence observed during the winter and fall than in the summer and spring. In the United States, acute bronchitis is the ninth most common illness among outpatients, as reported by physicians.3 Viruses are usually considered the cause of acute bronchitis but have been isolated in a minority of patients.1,4 Those isolated in acute bronchitis (from the most to the leastcommon in large series) include influenza A and B viruses, parainfluenza virus, respiratory syncytial virus, coronavirus, adenovirus, and rhinovirus. Human metapneumovirus has been identified as a causative agent.5-7 A recent French study involving adults who had been vaccinated against influenza showed a viral cause in 37% of 164 cases of acute bronchitis, of which 21% were rhinovirus.4 Thus,the yield of specific pathogens varies according to several factors, including the presence or absence of an epidemic, the season of the year, and the influenza vaccination status of the population. Bacterial species commonly implicated in community-acquired pneumonias are isolated from the sputum in a minority of patients with acute bronchitis.1 However, the role of these species in the disease orits attendant symptoms remains unclear, because bronchial biopsies have not shown bacterial invasion. In some cases, atypical bacteria are important causes, including Bordetella pertussis, Chlamydophila (Chlamydia) pneumoniae, and Mycoplasma pneumoniae.1 Some data have suggested that B. pertussis may underlie 13 to 32% of cases of cough lasting 6 days or longer, although in a recent prospectivestudy, B. pertussis comprised only 1% of cases of acute bronchitis.8
Pathobiology
From the Department of Internal Medicine, Virginia Commonwealth University, Richmond. Address reprint requests to Dr. Wenzel at the Department of Internal Medicine, Virginia Commonwealth University, 1101 E. Broad St., P.O. Box 980663, Richmond, VA 23298, or at rwenzel@ mcvh-vcu.edu. N Engl J Med 2006;355:2125-30.Copyright © 2006 Massachusetts Medical Society.

Acute bronchitis is thought to reflect an inflammatory response to infections of the epithelium of the bronchi. Epithelial-cell desquamation and denuding of the airway to the level of the basement membrane in association with the presence of a lymphocytic cellular infiltrate have been demonstrated after influenza A tracheobronchitis9;
n engl j med355;20 www.nejm.org november 16, 2006

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microscopical examination has shown thickening of the bronchial and tracheal mucosa corresponding to the inflamed areas. Such pathological...