Acute bronchitis is one of the most common diagnoses in ambulatory care medicine, accounting for 2.5 million physician visits per year. This condition is one of the top 10 diagnoses for which patients seek medical care. Acute bronchitis is one of the most common diagnoses made by primary care physicians.Viruses are the most common cause of acute bronchitis in otherwise healthy adults. Only a small portion of acute bronchitis infections are caused by nonviral agents, with the most common organisms being Mycoplasma pneumoniae and Chlamydia pneumoniae.
I. Diagnosis
A. The cough in acute bronchitis may produce either
clear or purulent sputum. This cough generally lasts seven to 10 days. Approximately 50 percent of patients with acute bronchitis have a cough that lasts up to three weeks, and 25 percent of patients have a cough that persists for over a month.
B. Physical examination. Wheezing, rhonchi, or a
prolonged expiratory phase may be present.
C. Diagnostic studies
1. The appearance of sputum is not predictive of
whether a bacterial infection is present. Purulent sputum is most often caused by viral infections. Microscopic examination or culture of sputum generally is not helpful. Since most cases of acute bronchitis are caused by viruses, cultures are usually negative or exhibit normal respiratory flora. M. pneumoniae or C. pneumoniae infection are not detectable on routine sputum culture.
2. Acute bronchitis can cause transient pulmonary
function abnormalities which resemble asthma. Therefore, to diagnose asthma, changes that persist after the acute phase of the illness must be documented. When pneumonia is suspected, chest radiographs and pulse oximetry may be helpful.
II. Pathophysiology
Selected Triggers of Acute Bronchitis
Viruses: adenovirus, coronavirus, coxsackievirus, enterovirus, influenza virus, parainfluenza virus, respiratory syncytial virus, rhinovirus
Bacteria: Bordetella pertussis, Bordetella parapertussis, Branhamella catarrhalis, Haemophilus influenzae, Strepto- coccus pneumoniae, atypical bacteria
(eg, Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella species)
Yeast and fungi: Blastomyces dermatitidis, Candida albicans, Candida tropicalis, Coccidioides immitis, Cryptococcus neoformans, Histoplasma capsulatum Noninfectious triggers: asthma, air pollutants, ammonia, cannabis, tobacco, trace metals, others
A. Acute bronchitis is usually caused by a viral infec-
tion. In patients younger than one year, respiratory syncytial virus, parainfluenza virus, and coronavirus are the most common isolates. In patients one to 10 years of age, parainfluenza virus, enterovirus, respiratory syncytial virus, and rhinovirus predomi- nate. In patients older than 10 years, influenza virus, respiratory syncytial virus, and adenovirus are most frequent.
B. Parainfluenza virus, enterovirus, and rhinovirus
infections most commonly occur in the fall. Influ- enza virus, respiratory syncytial virus, and coronavirus infections are most frequent in the winter and spring.
III. Signs and symptoms
A. Cough is the most commonly observed symptom of
acute bronchitis. The cough begins within two days of infection in. Most patients have a cough for less than two weeks; however, 26 percent are still coughing after two weeks, and a few cough for six to eight weeks.
B. Other signs and symptoms may include sputum
production, dyspnea, wheezing, chest pain, fever, hoarseness, malaise, rhonchi, and rales. Sputum may be clear, white, yellow, green, or tinged with blood. Color alone should not be considered indica- tive of bacterial infection.
IV. Physical examination and diagnostic studies A. The physical examination should focus on fever,
tachypnea, wheezing, rhonchi, and prolonged expiration. Evidence of consolidation is absent. Fever may be present in some patients with acute bronchitis. However, high fever should prompt
consideration of pneumonia or influenza.
B. Chest radiography should be reserved for patients
with possible pneumonia, heart failure, advanced age, chronic obstructive pulmonary disease, malig- nancy, tuberculosis, or immunocompromised or debilitated status.
V.Differential diagnosis
A. Acute bronchitis or pneumonia can present with
fever, constitutional symptoms and a productive cough. Patients with pneumonia often have rales. When pneumonia is suspected on the basis of the presence of a high fever, constitutional symptoms or severe dyspnea, a chest radiograph should be obtained.
Differential Diagnosis of Acute Bronchitis Disease
process
Signs and symptoms
Asthma Evidence of reversible airway obstruction even when not infected
Allergic aspergillosis
Transient pulmonary infiltrates
Eosinophilia in sputum and peripheral blood smear
Occupa- tional expo- sures
Symptoms worse during the work week but tend to improve during weekends, holidays and vacations
Chronic
bronchitis Chronic cough with sputum production on adaily basis for a minimum of three months Typically occurs in smokers
Sinusitis Tenderness over the sinuses, postnasal drainage
Common
cold Upper airway inflammation and no evidenceof bronchial wheezing Pneumonia Evidence of infiltrate on the chest radio-
graph Congestive
heart failure Basilar rales, orthopnea Cardiomegaly
Evidence of increased interstitial or alveolar fluid on the chest radiograph
S3 gallop, tachycardia
Reflux
esophagitis Intermittent symptoms worse when lyingdown Heartburn
Bronchoge nic tumor
Constitutional signs often present Cough chronic, sometimes with hemoptysis Aspiration
syndromes
Usually related to a precipitating event, such as smoke inhalation
Vomiting
Decreased level of consciousness
B. Asthma should be considered in patients with
repetitive episodes of acute bronchitis. Patients who repeatedly present with cough and wheezing can be given spirometric testing with bronchodilation to help differentiate asthma from recurrent bronchitis.
C. Congestive heart failure may cause cough,
shortness of breath and wheezing in older patients. Reflux esophagitis with chronic aspiration can cause bronchial inflammation with cough and wheezing. Bronchogenic tumors may produce a cough and obstructive symptoms.
VI. Treatment
A. Protussives and antitussives
1. Because acute bronchitis is most often caused
by a viral infection, usually only symptomatic treatment is required. Treatment can focus on preventing or controlling the cough (antitussive therapy).
2. Antitussive therapy is indicated if cough is creat-
ing significant discomfort. Studies have reported success rates ranging from 68 to 98 percent. Nonspecific antitussives, such as hydrocodone (Hycodan), dextromethorphan (Delsym), codeine (Robitussin A-C), carbetapentane (Rynatuss), and benzonatate (Tessalon), simply suppress cough.
Selected Nonspecific Antitussive Agents
Preparation Dosage Side effects
Hydromorphone -guaifenesin (Hycotuss) 5 mg per 100 mg per 5 mL (one teaspoon) Sedation, nau- sea, vomiting, respiratory de- pression Dextromethorph
an (Delsym) 30 mg every 12hours Rarely, gastroin-testinal upset or sedation
Hydrocodone (Hycodan syrup or tablets)
5 mg every 4 to
6 hours Gastrointestinalupset, nausea, drowsiness, constipation Codeine
(Robitussin A-C) 10 to 20 mg ev-ery 4 to 6 hours Gastrointestinalupset, nausea, drowsiness, constipation Carbetapentane
(Rynatuss) 60 to 120 mgevery 12 hours Drowsiness,gastrointestinal upset Benzonatate
(Tessalon) 100 to 200 mgthree times daily Hypersensitivity,gastrointestinal upset, sedation
B. Bronchodilators. Patients with acute bronchitis
who used an albuterol metered-dose inhaler are less likely to be coughing at one week, compared with those who received placebo.
C. Antibiotics. Physicians often treat acute bronchitis
with antibiotics, even though scant evidence exists that antibiotics offer any significant advantage over placebo. Antibiotic therapy is beneficial in patients with exacerbations of chronic bronchitis.
Oral Antibiotic Regimens for Bronchitis
Drug Recommended regimen
Azithromycin (Zithromax) 500 mg; then 250 mg qd Erythromycin 250-500 mg q6h Clarithromycin (Biaxin) 500 mg bid Levofloxacin (Levaquin) 500 mg qd Trovafloxacin (Trovan) 200 mg qd Trimethoprim/sulfamethoxa
zole (Bactrim, Septra) 1 DS tablet bid Doxycycline 100 mg bid
D. Bronchodilators. Significant relief of symptoms
occurs with inhaled albuterol (two puffs four times daily). When productive cough and wheezing are present, bronchodilator therapy may be useful. References, see page 282.