Bronchitis overview

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Bronchitis Main page

Patient Information

Overview

Causes

Classification

Acute bronchitis
Chronic bronchitis

Differential Diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Seyedmahdi Pahlavani, M.D. [2]

Overview

Bronchitis is an inflammation of the bronchi (medium-size airways) in the lungs.[1] Acute bronchitis is usually caused by viruses or bacteria and may last several days or weeks. Chronic bronchitis is not necessarily caused by infection and is generally part of a syndrome called chronic obstructive pulmonary disease (COPD); it is defined clinically as a persistent cough that produces sputum (phlegm), for at least three months in two consecutive years. The remainder of this article deals with acute bronchitis only. This is caused by a viral infection, such as a cold, or a bacterial infection. It also can result from breathing irritating fumes, such as those of tobacco smoke or polluted air. Constant coughing is the main symptom. Either type(chronic or acute) may lead to asthma or pneumonia.

Acute bronchitis is characterized by cough and sputum (phlegm) production and symptoms related to the obstruction of the airways by the inflamed airways and the phlegm, such as shortness of breath and wheezing. Diagnosis is by clinical examination and sometimes microbiological examination of the phlegm. Treatment may be with antibiotics (if a bacterial infection is suspected), bronchodilators (to relieve breathlessness) and other treatments.

Historical Perspective

In 1985, University of Newcastle, Australia Professor Robert Clancy developed an oral vaccine for acute bronchitis. This vaccine was commercialised four years later as Broncostat.[3]

Pathophysiology

Inflammatory response of the bronchial epithelium to infections or irritants that involve the medium and large size airways results in thickening of the bronchial and tracheal mucosa.
Bronchitis caused by influenza virus shows an epithelial-cell desquamation in association with the presence of a lymphocytic cellular infiltrate[2].
  • Chronic bronchitis:
Halmark features include:hyperplasia (increased number) and hypertrophy (increased size) of the goblet cells (mucous gland) of the airway, resulting in an increase in secretion of mucus which contributes to the airway obstruction.
Microscopically there is infiltration of the airway walls with inflammatory cells, particularly neutrophils. Inflammation is followed by scarring and remodeling that thickens the walls resulting in narrowing of the small airway. Further progression leads to metaplasia (abnormal change in the tissue) and fibrosis (further thickening and scarring) of the lower airway. The consequence of these changes is a limitation of airflow[3][4][5].

Causes

  • Acute Bronchitis: may be caused by either viral, bacterial or environmental causes.
Viruses: Influenza Virus,parainfluenza virus,respiratory syncytial virus, coronavirus, adenovirus, enterovirus, rhinovirus, coxsackievirus, and human metapneumovirus[6][7][8].
Bacteries: Mycoplasma pneumoniae and,Chlamydophila pneumoniae and Bordetella pertussis[9].
Environmental causes: Toxic fume inhalation, tobacco, dust and aerosol may result in acute bronchitis[10].
  • Chronic Bronchitis: caused by smoking,Air Pollutants,Occupational Exposures and Genetic factors

Differentiating Bronchitis from other Diseases

Bronchitis must be differentiated from other diseases that cause cough such as asthma,pneumonia,bronchectasis and CHF.

Epidemiology and demography

Acute bronchitis affects young children and old people. Its overall incidence is about 5% in the U.S. There is no racial or gender predilection for this disease[11][9][12]..
Chronic bronchitis is common in old ages affects white people more than others but is equal between males and females[13].

Risk Factors

Age, season of the year and the immunization status are the main determining risk factors for acquiring acute bronchitis[14][9][15].
The most potent risk factor in the development of chronic bronchitis is cigarette Smoking[16]. The others are occupational pollutants such as;cadmium and silica,air pollutants and genetic factors such as;alpha 1 antitrypsin deficiency[17].

Natural History, Complications and Prognosis

Acute bronchitis is a self limiting lower respiratory tract infection usually presents with cough that lasts for up to 3 weeks[14][18].
Chronic bronchitis usually gradually gets worse over time and can lead to death. The rate at which it gets worse varies between individuals and depends on the level of airflow obstruction. Acute bronchitis has very excellent prognosis[9]. Chronic bronchitis however is dependent on early recognition and smoking cessation which improves the outcome significantly.

Diagnosis

History and Symptoms

Bronchitis is usually a diagnosis of exclusion. Presence of cough without fever lasting more than 5 days and with normal vitals (no tachypnea or tachycardia) is suggestive of acute bronchitis. The presentation may vary according to the pathogen involved.

Physical Examination

A physical examination will often reveal decreased intensity of breath sounds, wheeze (rhonchi) and prolonged expiration. Most doctors rely on the presence of a persistent dry or wet cough as evidence of bronchitis.

Laboratory Findings

Acute bronchitis is usually a diagnosis of exclusion. A careful history and physical examination are very useful in doing a correct diagnosis. Other laboratory testings like antigen testing via multiplex PCR (polymerase chain reaction) and serological markers, can act as useful adjunct to the diagnosis. Nevertheless, these tests should be limited only for conditions when a pathogen is highly suspected, epidemic with a pathogen is present (influenza). These tests have limited availability and have not shown to be cost effective in outpatients department.

Treatment

Medical Therapy

Bronchitis is usually caused by a viral agent. The treatment of bronchitis is usually symptomatic with analgesics, decongestants, cough suppressant (codeine or hydrocodone-containing preparations or inhaled corticosteroids). Use of antibiotics should be limited to conditions when a diagnosis with a definitive pathogen is there. Oseltamivir for influenza (during influenza epidemics), and azithromycin for atypical bacterias like mycoplasma,chlamydiae has been shown useful in clinical trials.

References

  1. ↑ Bronchitis (Chest Cold) - Get Smart: Know When Antibiotics Work. Centers for Disease Control and Prevention (2015). http://www.cdc.gov/getsmart/community/for-patients/common-illnesses/bronchitis.html Accessed on July 28, 2016
  2. ↑ WALSH JJ, DIETLEIN LF, LOW FN, BURCH GE, MOGABGAB WJ (1961). "Bronchotracheal response in human influenza. Type A, Asian strain, as studied by light and electron microscopic examination of bronchoscopic biopsies". Arch. Intern. Med. 108: 376–88. PMID 13782910.
  3. ↑ Cosio MG, Saetta M, Agusti A (2009). "Immunologic aspects of chronic obstructive pulmonary disease". N. Engl. J. Med. 360 (23): 2445–54. doi:10.1056/NEJMra0804752. PMID 19494220.
  4. ↑ Kumar P, Clark M (2005). Clinical Medicine, 6ed. Elsevier Saunders. pp 900-901. ISBN 0702027634.
  5. ↑ McDonough JE, Yuan R, Suzuki M, Seyednejad N, Elliott WM, Sanchez PG, Wright AC, Gefter WB, Litzky L, Coxson HO, Paré PD, Sin DD, Pierce RA, Woods JC, McWilliams AM, Mayo JR, Lam SC, Cooper JD, Hogg JC (2011). "Small-airway obstruction and emphysema in chronic obstructive pulmonary disease". N. Engl. J. Med. 365 (17): 1567–75. doi:10.1056/NEJMoa1106955. PMC 3238466. PMID 22029978.
  6. ↑ Jonsson JS, Sigurdsson JA, Kristinsson KG, Guthnadóttir M, Magnusson S (1997). "Acute bronchitis in adults. How close do we come to its aetiology in general practice?". Scand J Prim Health Care. 15 (3): 156–60. PMID 9323784.
  7. ↑ Boivin G, Abed Y, Pelletier G, Ruel L, Moisan D, Côté S, Peret TC, Erdman DD, Anderson LJ (2002). "Virological features and clinical manifestations associated with human metapneumovirus: a new paramyxovirus responsible for acute respiratory-tract infections in all age groups". J. Infect. Dis. 186 (9): 1330–4. doi:10.1086/344319. PMID 12402203.
  8. ↑ Louie JK, Hacker JK, Gonzales R, Mark J, Maselli JH, Yagi S, Drew WL (2005). "Characterization of viral agents causing acute respiratory infection in a San Francisco University Medical Center Clinic during the influenza season". Clin. Infect. Dis. 41 (6): 822–8. doi:10.1086/432800. PMID 16107980.
  9. ↑ 9.0 9.1 9.2 9.3 Wenzel RP, Fowler AA (2006). "Clinical practice. Acute bronchitis". N. Engl. J. Med. 355 (20): 2125–30. doi:10.1056/NEJMcp061493. PMID 17108344.
  10. ↑ Irwin RS, Madison JM (2000). "The diagnosis and treatment of cough". N. Engl. J. Med. 343 (23): 1715–21. doi:10.1056/NEJM200012073432308. PMID 11106722.
  11. ↑ Macfarlane J, Holmes W, Gard P, Macfarlane R, Rose D, Weston V, Leinonen M, Saikku P, Myint S (2001). "Prospective study of the incidence, aetiology and outcome of adult lower respiratory tract illness in the community". Thorax. 56 (2): 109–14. PMC 1746009. PMID 11209098.
  12. ↑ Ferri FF. Ferri's Clinical Advisor 2016, 5 Books in 1. Elsevier Health Sciences; 2015.
  13. ↑ wrongdiagnosis.com > Prevalence and Incidence of COPD Retrieved on Mars 14, 2010
  14. ↑ 14.0 14.1 Gonzales R, Sande MA (2000). "Uncomplicated acute bronchitis". Ann. Intern. Med. 133 (12): 981–91. PMID 11119400.
  15. ↑ Albert RH (2010). "Diagnosis and treatment of acute bronchitis". Am Fam Physician. 82 (11): 1345–50. PMID 21121518.
  16. ↑ MedicineNet.com - COPD causes
  17. ↑ MedlinePlus Medical Encyclopedia
  18. ↑ Landau LI (2006). "Acute and chronic cough". Paediatr Respir Rev. 7 Suppl 1: S64–7. doi:10.1016/j.prrv.2006.04.172. PMID 16798599.


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