A cough is a sudden expulsion of air through the large breathing passages that can help clear them of fluids, irritants, foreign particles and microbes. As a protective reflex, coughing can be repetitive with the cough reflex following three phases: an inhalation, a forced exhalation against a closed glottis, and a violent release of air from the lungs following opening of the glottis, usually accompanied by a distinctive sound.Frequent coughing usually indicates the presence of a disease. Many viruses and bacteria benefit, from an evolutionary perspective, by causing the host to cough, which helps to spread the disease to new hosts. Most of the time, irregular coughing is caused by a respiratory tract infection but can also be triggered by choking, smoking, air pollution, asthma, gastroesophageal reflux disease, post-nasal drip, chronic bronchitis, lung tumors, heart failure and medications such as angiotensin-converting-enzyme inhibitors (ACE inhibitors). Treatment should target the cause; for example, smoking cessation or discontinuing ACE inhibitors. Cough suppressants such as codeine or dextromethorphan are frequently prescribed, but have been demonstrated to have little effect. Other treatment options may target airway inflammation or may promote mucus expectoration. As it is a natural protective reflex, suppressing the cough reflex might have damaging effects, especially if the cough is productive. Presentation
Complications
The complications of coughing can be classified as either acute or chronic.
Unlike alcohol, the onset and disappearance are near instantaneous. A diver may be quite clear-headed at 20 meters, and yet giddy and silly at 30 meters. Ascending to 20 meters will almost instantly clear the head. High pressure nervous syndrome (HPNS)
Barotrauma
Barotrauma is injury caused by pressure effects on gas spaces. This may occur during ascent or descent. The ears are the most commonly affected body part. The most serious injury is lung barotrauma, which can result in pneumothorax, pneumomediastinum, pneumopericardium, subcutaneous emphysema, and arterial gas embolism. All divers, commercial air travelers, people traveling overland between different altitudes, and people who work in pressurized environments have had to deal with some degree of barotrauma effect upon their ears, sinuses, and other air spaces. At the most extreme, barotrauma can cause ruptured eardrums, bleeding sinuses, exploding tooth cavities, and the lung injuries described above. This is the reason why divers follow a procedure of not holding their breath during ascent. By breathing continuously, they keep the airways open and avoid pressure differences between their lungs and ambient pressure. Arterial gas embolism (AGE)
Arterial gas embolism (AGE) is a complication of lung barotrauma of ascent. It occurs when breathing gas is introduced to the circulation on the arterial side via lung over-pressure trauma. AGE can present in similar ways to arterial blockages seen in other medical situations. Affected people may suffer strokes, with paralysis or numbness down one side; they may suffer heart attacks; they may suffer pulmonary embolism with shortness of breath and chest pain.