Coughing

Larry A. Law

The respiratory tract is abundant in nerve endings, some of which are known as cough receptors, located in the throat, vocal cords, and upper airway of the lungs. They react to foreign substances and stimuli; when activated, they trigger the cough reflex to expel mucus or foreign objects. Coughing isn't a disease, but sometimes it can feel like it. According to Dr. Klan Fan Chung at the National Heart & Lung Institute at the Imperial College London, "Coughing is very much a natural and protective thing; it protects our lungs." When we cough, there is usually a deep gasp which allows air to penetrate our lungs. Then, the glottis (part of the larynx consisting of the vocal cords and the opening between them) closes, covering the airway, while muscles in the chest and abdomen contract forcefully. This involuntary movement induces a significant increase in chest pressure. Finally, the glottis opens suddenly and air rushes out at speeds close to 50 miles per hour. Mucus and foreign particles are carried out with that release of air. Incredibly, during vigorous coughing, the air speed approaches the speed of sound, ​creating the barking noise that we call a cough.

Causes of a Cough

A cough can be a conscious, voluntary act or an uncontrollable, involuntary reflex. In the latter case, stimulation of nerves in the larynx ("voice box") and respiratory tract initiates the entire process. These nerves can be irritated by infections, allergies, cold air, tumors, chemical agents such as smoke, mechanical factors such as dust particles, or by normal body fluids such as nasal mucus or stomach acid. It's no wonder, then, that so many different things can trigger a cough.

Cough Types

The picture above featured in The Epoch Times shows the 3 types of coughs governed by the length of time exhibited. Observing the types of secretions expelled during coughing is also important as it can indicate if there is a bacterial infection. Everyone coughs, and nobody worries about an occasional cough. Many acute illnesses — ranging from hay fever and the common cold to bronchitis and pneumonia — produce recurrent coughs. But the cough that accompanies acute illnesses resolves in a matter of a few days to a few weeks. In contrast, a chronic cough is defined as one that lingers for more than three to eight weeks, sometimes lasting for months or even years.

Chronic, Persistent Coughs

Chronic coughing is common — so frequent that it rates as one of the most common reasons for seeing a doctor. In addition to worry about the cause of the cough, patients experience frustration and anxiety, especially if diagnosis and treatment stretches out over weeks, which is often the case. Coughing interrupts sleep, producing fatigue and impairing concentration and work performance. Coughing can also have important physical consequences, ranging from urinary incontinence to fainting and broken ribs. Between medical tests, lost productivity at work, remedies that don't help, and treatments that do, coughing can become expensive. Upper airway cough syndrome, cough-variant asthma, and acid reflux account for two-thirds of all diagnoses of chronic cough.

Refractory Chronic Cough

​If a doctor treats the patient for all three of these possible underlying causes, and the cough has no improvement, “at that point, it’s a cough [that] meets the definition of refractory chronic cough,” explained Dr. Peter Dicpinigaitis, professor of medicine in the Division of Critical Care Medicine at the Albert Einstein College of Medicine. Refractory chronic cough is caused by “a hypersensitivity of the cough reflex,” he said. In his experience, approximately 30 percent to 40 percent of patients with chronic cough belong in this category.

Individuals with unidentified causes tend to be older than age 40, with an average age of 55. They are predominantly female, outnumbering males by two to one, according to Dr. Chung. These patients experience hypersensitivity in their nerves, akin to an overly-sensitive security alarm system in a house triggered by the slightest breeze. Factors such as changes in temperature, the scent of perfume, or even laughter can set off this alarm.

Furthermore, the role of the brain is crucial. According to Dr. Chung, if there are issues with the brain’s control of cough signals, it is comparable to having an unreasonable circuit breaker setting behind the alarm system, leading to frequent false alarms. A doctor’s strategy for managing these types of coughs is to suppress them as much as possible to reduce patient suffering, according to Dr. Dicpinigaitis (professor of medicine at Albert Einstein College of Medicine). “However, we do not have any particularly good baseline effective medications to treat this refractory chronic cough,” he said. Fortunately, these patients often take proactive measures to identify triggers causing their coughs and engage in self-learning, adopting measures such as sucking on lozenges, ice, and staying hydrated.

Dr. Chung also emphasized the importance of keeping the throat moist, as dryness can stimulate cough receptors, making them more sensitive. It is always advisable to carry a small bottle of water. Additionally, stay in a warm environment and avoid cold stimuli. Chronic cough may also be related to vocal cord dysfunction. Dr. Chung mentioned that some experienced speech therapists can guide patients in attempts to suppress the urge to cough.

In addition, mental factors and stress can produce many physical symptoms, including cough. Psychogenic coughing increases at times of stress and disappears during sleep. Unfortunately, some people may never identify the cause of their cough, Dr. Rizzo (chief medical officer of the American Lung Association and clinical assistant professor of medicine at the Sidney Kimmel Medical College of Thomas Jefferson University) said.