Bronchitis is the medical term for inflammation of the lining of the bronchial tree, including the bronchi and/or bronchioles. It often involves the terminal part of the trachea as well. The walls of the bronchi and/or bronchioles become swollen due to inflammation and secrete excessive amounts of mucus. This causes a narrowing of the airway leading to a difficulty breathing (dyspnea), wheeze and a persistent cough.
Bronchitis may be acute, lasting less than 3 weeks (usually 10 to 14 days) or chronic, which is considered as a productive cough present for at least 3 months that recurs in 2 consecutive years.
Often acute bronchitis does not occur on its own. It may be preceded or accompanied by inflammation elsewhere in the respiratory tract, namely pharyngitis (pharynx) or laryngitis (larynx). Acute bronchitis frequently occurs with viral infections, particularly seasonal flu or the common cold, and may often be a complication related to the inadequate treatment and poor management of upper respiratory tract infections. Inflammation that extends further down the respiratory tract, beyond the bronchial tubes and into the lung tissue is known as pneumonia.
Chronic bronchitis is a result of recurrent inflammation of the bronchi and/or bronchioles. Eventually there is degeneration in this part of the airway with subsequent narrowing that is long lasting or sometimes permanent. This ultimately affects the ventilation which is a core function of the respiratory system. Therefore chronic bronchitis falls into the broader category of chronic obstructive pulmonary disease and has to be managed appropriately to prevent long term complications.
Bronchitis and Asthma
These are two airway diseases that are commonly mistaken for each other. Both affect the lower respiratory tract.
Asthma is the narrowing of the airways as a result of bronchospasm (spasm of the muscles lining the bronchial tubes). Similar to bronchitis, mucus secretion and bronchial wall swelling may also occur in asthma. It is mainly a result of immune mediated hypersensitivity (allergies) or heightened airway reactivity. In the past, asthma used to be known as ‘wheezy bronchitis’.
Bronchitis also results in narrowing of the airway as a result of mucus hypersecretion and bronchial wall swelling. Bronchospasm is usually not a key feature of this disease unlike in asthma. It is often a result of infectious and chemical agents irritating the airway.
Abnormal breathing sounds like a wheeze are present in both asthma and bronchitis.
- Laryngotracheobronchitis – inflammation of the lining of the respiratory tract extending from the larynx to the bronchi and/or bronchioles. Also known as croup.
- Tracheitis – inflammation of the lining of the trachea (wind pipe).
- Tracheobronchiolitis – inflammation of the airway lining extending from the trachea to the bronchioles (tracheobronchial tree).
- Bronchiolitis – inflammation of the lining of the bronchioles. Often used synonymously with the term bronchitis because the bronchioles are part of the bronchial tree.
- Bronchopneumonia – inflammation of the lining of the lower airways extending from the bronchi to the lung parenchymal tissue.
Article reviewed by Dr. Greg. Last updated on September 16, 2010