|Classification and external resources|
Chronic bronchitis is a chronic inflammation of the bronchi (medium-size airways) in the lungs. It is generally considered one of the two forms of chronic obstructive pulmonary disease (COPD), the other being emphysema. It is defined clinically as a persistent cough that produces sputum (phlegm) and mucus, for at least three months per year in two consecutive years.
Signs and symptoms 
Bronchitis may be indicated by a cough that produces sputum (also known as a productive cough), shortness of breath (dyspnea) and wheezing. Occasionally chest pains, fever, and fatigue or malaise may also occur. Mucus is often green or yellowish green and also may be orange or pink, depending on the pathogen causing the inflammation.
Chronic bronchitis is caused by recurring injury or irritation to the respiratory epithelium of the bronchi, resulting in chronic inflammation with infiltration of CD8+ T cells, macrophages, and neutrophils, edema (swelling), and thickened fibrotic bronchial walls with luminal narrowing. Increased numbers of mucus-producing cells in the bronchi and bronchioles and enlargement of the tracheal mucus glands results in an increased secretion of mucus. Airflow resistance characteristic of chronic bronchitis is primarily due to goblet cell metaplasia creating mucus plugs in the bronchioles with concurrent bronchiolar fibrosis and inflammation.
A variety of tests may be performed in patients presenting with cough and shortness of breath:
- Pulmonary Function Tests (PFT) (or spirometry) must be performed in all patients presenting with chronic cough. An FEV1/FVC ratio below 0.7 that is not fully reversible after bronchodilator therapy indicates the presence of COPD, that requires more aggressive therapy and carries a more severe prognosis than simple chronic bronchitis.
- A chest X-ray that reveals hyperinflation; collapse and consolidation of lung areas would support a diagnosis of pneumonia. Some conditions that predispose to bronchitis may be indicated by chest radiography.
- A sputum sample showing neutrophil granulocytes (inflammatory white blood cells) and culture showing that has pathogenic microorganisms such as Streptococcus spp.
- A blood test would indicate inflammation (as indicated by a raised white blood cell count and elevated C-reactive protein).
- Neutrophils infiltrate the lung tissue, aided by damage to the airways caused by irritation.
- Damage caused by irritation of the airways leads to inflammation and leads to neutrophils being present
- Mucosal hypersecretion is promoted by a substance released by neutrophils
- Further obstruction to the airways is caused by more goblet cells in the small airways. This is typical of chronic bronchitis
- Although infection is not the reason or cause of chronic bronchitis it is seen to aid in sustaining the bronchitis.
- High Resolution Computed Tomography (HRCT) — This is a special type of CT scan that provides your doctor with high-resolution images of your lungs. Having a HRCT is no different than having a regular CT scan; they both are performed on an open-air table and take only a few minutes.
Only about 5-10% of bronchitis cases are caused by a bacterial infection. Most cases of bronchitis are caused by a viral infection and are "self-limited" and resolve themselves in a few weeks. For acute exacerbations of chronic bronchitis, if antibiotics are used, amoxicillin or doxycycline is recommended.
In 2009, it was estimated that approximately 10 million Americans were diagnosed with chronic bronchitis by a physician with rates highest in the 18–44 year old age population. American women were diagnosed with chronic bronchitis at twice the rate as American men.
Dr. Charles Badham first distinguished bronchitis from other respiratory disorders in 1808. Before this distinction was made, early medical systems such as Ayurveda, ancient Greek medicine, and Traditional Chinese Medicine proposed numerous hypotheses to explain pulmonary disease. The majority of these hypotheses centered on the premise that respiratory disease resulted from an imbalance in fundamental forces such as Qi or the four humors. Treatments used to treat respiratory disease were varied and were often unrelated to the prevailing medical hypotheses and included: incense drugs, spices, herbs, certain foods, expectorants, and venesection (venipuncture). Modern pharmaceutical approaches to bronchitis expanded greatly in the twentieth century after pharmacologically active compounds demonstrated to have bronchodilating properties were isolated from earlier mainstream therapies. Isolated agents included adrenergic drugs such as adrenaline and ephedrine, anticholinergic agents such as atropine and scopolamine, the expectorant acetylcysteine, and theophylline.
Acute exacerbations 
Acute exacerbations of chronic bronchitis (AECB) are episodes of difficulty in breathing in a person with chronic bronchitis.
During AECB, breathing becomes much more difficult because of further narrowing of the airways, in addition to increased secretion of mucus, which often is thicker than usual.
Treatment of AECB may include:
- Cough suppressants
- Inhaled bronchodilators
- Antibiotics are used if a bacterial infection is the suspected cause. However, antibiotics will not treat exacerbations caused by viruses.
- Oxygen therapy
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|Wikisource has the text of the 1911 Encyclopædia Britannica article Bronchitis.|
- About.com - Chronic Bronchitis
- NIH Medline Plus - Bronchitis
- Familydoctor.org - Chronic Bronchitis
- eMedicineHealth - Bronchitis