Air is pulled into the lungs when we breathe, initially passing through the mouth, nose, and larynx (voicebox) into the trachea and continues en route to each lung via either the right or left bronchi (the bronchial tree - bronchi, bronchioles, and alveoli).
Bronchi are formed as the lower part of the trachea divides into two tubes that lead to the lungs. As the bronchi get farther away from the trachea, each bronchial tube divides and gets smaller (resembling an inverted tree) to provide the air to lung tissue so that it can transfer oxygen to the blood stream and remove carbon dioxide (the waste product of metabolism).
Bronchitis describes inflammation of the bronchial tubes (inflammation = itis). The inflammation causes swelling of the lining of these breathing tubes, narrowing the tubes and promoting secretion of inflammatory fluid.
Acute bronchitis describes the inflammation of the bronchi usually caused by a viral infection, although bacteria and chemicals also may cause acute bronchitis.Bronchiolitis is a term that describes inflammation of the smaller bronchi referred to as bronchioles.
In infants, this is usually caused by respiratory syncytial viruses (RSV), and affects the small bronchi and bronchioles more than the large. In adults, other viruses as well as some bacteria can cause bronchiolitis and often manifest as a persistent cough at times productive of small plugs of mucus.
Acute bronchitis is as mentioned above, is a cough that begins suddenly usually due to a viral infection involving the larger airways. Colds (also known as viral upper airway infections) often involve the throat (pharyngitis) and nasal passages, and at times the larynx (resulting in a diminished hoarse voice, also known as laryngitis).
Symptoms can include a runny nose, nasal stuffiness, and sore throat. Croup usually occurs in infants and young children and involves the voice box and upper large airways (the trachea and large bronchi).
Chronic bronchitis for research purposes is defined as a daily cough with sputum production for at least three months, two years in a row. Chronic bronchitis is a diagnosis usually made based on clinical findings of a long term persistent cough usually associated with tobacco abuse. From a pathologic standpoint, characteristic microscopic findings involving inflammatory cells in seen in airway tissue samples make the diagnosis.
When referring to pulmonary function testing, a decrease in the ratio of the volume of airflow at 1 second when compared to total airflow is less than 70%. This confirms the presence of obstructive airways disease of which chronic bronchitis is one type. Certain findings can be seen on imaging studies (chest X-ray, and CT or MRI of the lungs) to suggest the presence of chronic bronchitis; usually this involves an appearance of thickened tubes.
Inflammation of the bronchial tubes narrows the inside opening of the bronchial tubes. Narrowing of the bronchial tubes result in increased resistance, this increase makes it more difficult for air to move to and from the lungs. This can cause wheezing, coughing, and shortness of breath.
The cough may consist of sputum due to the secretions from the inflamed cells that line the bronchi. By coughing, the body attempts to expel secretions that clog the bronchial tubes. If these secretions contain certain inflammatory cells, discoloration of the mucus may result often in a green or yellow color. Sometimes the severity of the inflammation may result in some bleeding.
As with any other infection, there may be associated fever, chills, aches, soreness and the general sensation of feeling poorly or malaise.
Acute bronchitis occurs most often due to a viral infection that causes the inner lining of the bronchial tubes to become inflamed and undergo the changes that occur with any inflammation in the body.
Common viruses include the rhinovirus, respiratory syncytial virus (RSV), and the influenza virus.
Bacteria can also cause bronchitis (a few examples include,Mycoplasma, Pneumococcus, Klebsiella, Haemophilus).
Chemical irritants (for example, tobacco smoke, gastric reflux, solvents) can cause acute bronchitis.
Decreasing inflammation is the goal for treating acute bronchitis. Albuterol inhalation, either with a hand held device (meter dosed inhaler, MDI) or nebulizer will help dilate the bronchial tubes.
Short-term steroid therapy will help minimize inflammation within the bronchial tubes. Prednisone is a common prescription medication that enhances the anti-inflammatory effects of the steroids produced within the body by the adrenal glands. Topical inhaled steroids may also be of benefit with fewer potential side effects.
It is important to keep the patient comfortable by treating fever with acetaminophen or ibuprofen. Drinking plenty of fluid will keep the patient well hydrated and hydration keeps secretions into the bronchial tubes more liquid and easier to expel.
Antibiotics are not necessarily indicated for the treatment of acute bronchitis. Occasionally they may be prescribed should a bacterial infection be present in addition to the usual virus that causes acute bronchitis. However, most acute bronchitis is caused by viruses and no antibiotics are needed.
Although good hydration will help remove secretions into the bronchi, other treatments (for example, Mucinex, Robitussin and others that containguaifenesin) can help clear secretions though this is often a highly variable finding.
Cough is a very violent action that results in dynamic collapse of the airways. This collapse results in the walls of the airways banging against one another. This action of cough can cause further inflammation and help perpetuate the problem by sustaining and increasing inflammation.
Cough suppression with cough drops or other liquid suppressants (for example, Vicks 44, Halls, and cough syrups that contain dextromethorphan) help to break this vicious cycle. In addition, if the person smokes, they should stop. If the acute bronchitis is being caused by inhaled smoke or chemicals, the patient should be removed from these irritant sources.