Cough
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A cough is a sudden, often repetitive, spasmodic contraction of the thoracic cavity, resulting in violent release of air from the lungs, and usually accompanied by a distinctive sound. Coughing is an action the body takes to get rid of substances that are irritating the air passages. A cough is usually initiated to clear a buildup of phlegm in the trachea; air may move through this passage at up to 480 km/h (300 mph) during a contraction. Coughing can also be triggered by a bolus of food going down the trachea instead of the esophagus, due to a failure of the epiglottis, although this may result in choking instead. Frequent or chronic coughing usually indicates the presence of a disease. Provided the patient is a non-smoker and has a normal chest X-ray, the cause of chronic cough in 93% of all patients is due to asthma, reflux (heartburn) or post-nasal drip. Other causes of chronic cough include chronic bronchitis and medications such as ACE inhibitors. Coughing can happen voluntarily as well as involuntarily.
Cause
The physiological action of coughing is responsible in part to the vagus nerve, which runs through the lungs to the brain. The vagus nerve is activated when capsaicin is released, which stimulates the sensory nerve endings. Centrally acting cough suppressants, such as codeine and dextromethorphan, reduce the urge to cough by inhibiting the capsaicin-induced sensory nerve by depolarization of the vagus nerve. One of the common presentations to the medical practitioner is dry cough. The common causes of chronic dry cough include post nasal drip, Gastroesophageal reflux disease, Cough variant asthma, Drugs like beta blockers, ACE inhibitors, Aspirin which should be asked for in people above 40 years, Post viral bronchial hyperresponsiveness and Habitual Cough. It should be noted that when cough lasts for more than few weeks multiple causes are likely and only when all the causes are treated will the patient be symptom free.
Beyond the physiological reasons for coughing there are also psychological reasons for coughing otherwise known as psychogenic coughing or habit coughing. We are all familiar with a person who coughs or clears their throat before a public speech as a means to gain the attention of the audience and perhaps releave their own nerviousness. Steruphilia is a condition of loving the sound of coughing or sneezing. If one has ever sat next to someone who seems to enjoy coughing or sneezing loudly they might have hay-fever, or they might possibly be a steruphiliac.
Coughs can also be used to send information. See the Charles Ingram story.
Complications
The complications of Cough can be classified as Acute or Chronic. Acute complications include Cough Syncope, fainting spells when coughs are prolonged and forceful due to decreased blood flow to the brain secondary to raised intrathoracic pressure due to cough. Other acute complications include inability to sleep, cough induced vomiting, chest pain due to muscular strain of incessant coughing, rupture of bulla causing pneumothorax.In severe cases, prolonged coughing can cause fatigue fractures of lower ribs and costochondritis, an inflammation of the connective tissue between the breastbone and the ribs. Chronic complications are commonly noted. In certain cases, it can even lead to abdominal or pelvic hernias. In women with prolapse uterus cough can cause cough micturition which can be a major social nuisance. Cough defecation can also be noted.
Treatment
Coughs can be treated with cough medicines. Dry coughs are treated with cough suppressants (antitussives) that suppress the body's urge to cough, while productive coughs (coughs that produce phlegm) are treated with expectorants that loosen mucus from the respiratory tract.
See also
- Whooping cough
- Kennel cough
- Cough medicines, including expectorants
- Charles Ingram - famously accused of using coughing to cheat on Who wants to be a millionaire?
- Psychogenic Coughing
- Habit Cough
- Steruphilia - the love of coughing and sneezing