Bronchitis, Acute

Definition, Etiology, Pathogenesis Top

Acute bronchitis is an acute respiratory infection characterized by a cough lasting <3 weeks. Diagnosis is established after excluding pneumonia.

Causes: Most frequently, respiratory viruses (influenza A and B viruses, parainfluenza viruses, respiratory syncytial virus, coronaviruses [other than severe acute respiratory syndrome coronavirus 2, or SARS-CoV-2], adenoviruses, or rhinoviruses). Bacterial infections are found in <10% of patients and are most commonly caused by Bordetella pertussis, Mycoplasma pneumoniae, and Chlamydophila pneumoniae.

Clinical Features and Natural History Top

1. Symptoms: Fever, malaise, muscle pain, cough, production of mucous or purulent sputum. Wheezing may be observed in some patients. Symptoms of a viral infection of the upper respiratory tract (see Common Cold (Nonspecific Infections of the Upper Respiratory Tract)) often occur initially, and after a few days, symptoms of a lower respiratory tract infection appear.

2. Signs: Wheezes and rhonchi may be audible over the entire lungs. The disease usually resolves spontaneously.

Diagnosis Top

Pneumonia must be excluded; features suggesting the absence of pneumonia include heart rates <100 beats/min, respiratory rates <24 breaths/min, body temperature (oral) <38 degrees Celsius, lack of signs indicative of infiltrates on physical examination. Absence of the abovementioned symptoms decreases the likelihood of coronavirus disease 2019 (COVID-19) but cannot exclude the disease. Therefore, in certain clinical settings, investigations are necessary.

In patients with suspected pneumonia, perform a chest radiograph. If symptoms persist >3 weeks and spirometry reveals features of airflow obstruction, differential diagnosis should include asthma or chronic obstructive pulmonary disease. In equivocal cases, spirometry may be supplemented with a bronchial hyperresponsiveness test after the symptoms of infection have resolved.

Treatment Top

1. Symptomatic treatment: Antipyretics and cough suppressants may be used.Evidence 1Weak recommendation (benefits likely outweigh downsides, but the balance is close or uncertain; an alternative course of action may be better for some patients). Low Quality of Evidence (low confidence that we know true effects of the intervention). Quality of Evidence lowered due to the lack of experimental data. This suggestion is based on the current pattern of practice.

2. Do not use antibiotics unless pertussis is diagnosed.Evidence 2Weak recommendation (downsides likely outweigh benefits, but the balance is close or uncertain; an alternative course of action may be better for some patients). Moderate Quality of Evidence (moderate confidence that we know true effects of intervention). Quality of Evidence lowered due to inconsistency of findings among different outcomes. Smith SM, Fahey T, Smucny J, Becker LA. Antibiotics for acute bronchitis. Cochrane Database Syst Rev. 2014 Mar 1;3:CD000245. doi:10.1002/14651858.CD000245.pub3. Review. PubMed PMID: 24585130.

3. In patients with symptoms of acute bronchitis during an influenza epidemic, consider administration of antiviral agents active against influenza viruses within 48 hours of the onset of symptoms.Evidence 3Weak recommendation (benefits likely outweigh downsides, but the balance is close or uncertain; an alternative course of action may be better for some patients). Moderate Quality of Evidence (moderate confidence that we know true effects of intervention). For the effect on symptoms in previously healthy participants, Quality of Evidence is not downgraded. For the effect on reducing complications, Quality of Evidence downgraded to moderate because of imprecision, diagnostic uncertainty in measuring outcomes, indirectness to high-risk individuals, and potential publication bias. The interpretation of existing evidence differs (see http://www.bmj.com/content/345/bmj.e7303). Jefferson T, Jones M, Doshi P, Spencer EA, Onakpoya I, Heneghan CJ. Oseltamivir for influenza in adults and children: systematic review of clinical study reports and summary of regulatory comments. BMJ. 2014 Apr 9;348:g2545. doi:10.1136/bmj.g2545. Review. PubMed PMID: 24811411; PubMed Central PMCID: PMC3981975. Kaiser L, Wat C, Mills T, Mahoney P, Ward P, Hayden F. Impact of oseltamivir treatment on influenza-related lower respiratory tract complications and hospitalizations. Arch Intern Med. 2003 Jul 28;163(14):1667-72. PubMed PMID:12885681.

4. Inhaled beta2-agonists should be used only in patients with signs of airway obstruction (see Asthma).Evidence 4Weak recommendation (benefits likely outweigh downsides, but the balance is close or uncertain; an alternative course of action may be better for some patients). Moderate Quality of Evidence (moderate confidence that we know true effects of intervention). Quality of Evidence lowered due to imprecision and subgroup analysis. Becker LA, Hom J, Villasis-Keever M, van der Wouden JC. Beta2-agonists for acute bronchitis. Cochrane Database Syst Rev. 2011 Jul 6;(7):CD001726. doi:10.1002/14651858.CD001726.pub4. Review. PubMed PMID: 21735384.