Gastroesophageal reflux disease, commonly known as GERD, is the third-most common cause of chronic unexplained cough. A chronic unexplained cough is a cough that lasts for longer than three weeks in patients with no prior history of chronic respiratory disease and for whom cough is the only symptom present. Cough caused by GERD is triggered by both upper respiratory tract irritation (by esophageal-tracheobronchial reflex) and the lower respiratory tract (by aspiration).
Prevalence
GERD is a common affliction, with approximately ten percent of the adult population suffering from daily heartburn. Diagnostic testing confirms GERD to be the cause of the chronic cough between ten and 40 percent of cases, depending upon the tests performed (the highest percentage is found when doctors perform the 24-hour esophageal pH testing).
Symptoms
Common symptoms of a GERD-related cough include heartburn, oral regurgitation of acid and water brash, which is the sour taste in your mouth. Approximately 50 percent of patients do not exhibit classical symptoms of GERD, so they must pay attention to when and which foods may trigger cough. Hoarseness in the morning, nighttime cough or cough that is worse after lying down or exercising can indicate GERD. Cough following the consumption of chocolates, caffeine, alcohol or peppermint is also indicative of GERD.
Esophageal-Tracheobronchial Reflex
The reflux of acid into the distal (farthest) part of the esophagus stimulates the esophageal-tracheobronchial reflex. The distal portion contains pulmonary stretch receptors, also known as irritant receptors, which are the sensory nerves that stimulate the cough center in the brain. The distal portion of the esophagus also contains C-fibers and slowly adapting pulmonary stretch receptors, both of which are believed to modulate cough.
Microaspiration
Microaspiration occurs when a small amount of the fluid from the reflux enters the bronchial tubes and/or lungs. This can cause inflammation of the larynx or the bronchi, leading to a cough that is sometimes accompanied by hoarseness.
The Cycle
The mechanism of coughing often causes the lower esophageal sphincter to relax, thereby inducing acid reflux. When the cause of the cough is GERD, acid reflux causes the cough, and the cough makes the acid reflux worse, creating a perpetual cycle. The only way to break the cycle is to effectively manage both the cough and the acid reflux.
Management
Aggressive anti-reflux therapy leads to resolution of the cough in most cases when GERD is the only cause. Effective management involves a combination of dietary, mechanical (such as sleeping with your head raised) and drug therapies. Changing your diet to include high protein and low-fat foods, along with eliminating acidic or spicy foods can greatly reduce GERD symptoms and related cough. In addition, limiting large meals and in-between meal snacks helps to reduce symptoms.
Drug therapies include prokinetic agents, which work to enhance gastrointestinal motility, thereby reducing reflux activity and gastric acid inhibitors. There are two types of inhibitors--H2 antagonists, which block the action of histamine in the stomach and reducing the production of acid; and proton pump inhibitors, which block the enzyme system of the cells in the stomach and inhibit acid secretion.
