What is acid reflux?

Extraesophageal Manifestations
It has been suggested that GER may be the cause of a wide spectrum of conditions including noncardiac chest pain, asthma, posterior laryngitis, chronic cough, recurrent pneumonitis, and even dental erosion. Some of these patients have classical reflux symptoms, but many are “silent refluxers,” contributing to problems in making the diagnosis. Furthermore, it may be difficult to establish a causal relationship even if GER can be documented by testing (e.g., pH studies), because patients may simply have two common diseases without a cause-and-effect relationship.

Chest Pain

GER-related chest pain may mimic angina pectoris. The chest pain is usually described as squeezing or burning, substernal in location, and radiating to the back, neck, jaw, or arm. It often is worse after meals, awakens the patient from sleep, and may worsen during periods of emotional stress. Heavy exercise, even treadmill testing, may provoke GER. Reflux-related chest pain may last minutes to hours, often resolves spontaneously, and may be eased with antacids. Most patients with GERD-induced chest pain have heartburn symptoms. Early studies suggested that spastic motility disorders were the most common esophageal cause of chest pain. However, more recent studies using ambulatory esophageal pH and pressure monitoring suggest that about 25% to 50% of patients with noncardiac chest pain have GERD. Overall, these series of reports found that 41% of patients had abnormal 24-hour pH test results, whereas 32% had chest pain that was clearly associated with acid reflux. Patients with coronary artery disease commonly have coexisting esophageal diseases, but the evidence that GER causes ischemic pain is controversial. The mechanism for GERD-related chest pain is not clearly understood and probably is multifactorial, related to H + ion concentration, volume and duration of acid reflux, and secondary esophageal spasm.

Asthma and Other Pulmonary Diseases

The association of GERD and pulmonary diseases was recognized by Sir William Osler, who recommended that asthmatic patients should “learn to take their large daily meal at noon to avoid nighttime asthma which occurred if they ate a full supper.” More recent studies suggest the coexistence of the two diseases in up to 80% of asthmatic patients, irrespective of the use of bronchodilators. GERD should be considered in asthmatic patients who present in adulthood, those without an intrinsic component, and those not responding to bronchodilators or steroids. Up to 30% of patients with GERD-related asthma have no other esophageal complaints. Other pulmonary diseases associated with GERD include aspiration pneumonia, interstitial pulmonary fibrosis, chronic bronchitis, bronchiectasis, and possibly cystic fibrosis, neonatal bronchopulmonary dysplasia, and sudden infant death syndrome. Proposed mechanisms of reflux-induced asthma are either aspiration of gastric contents into the lungs with secondary bronchospasm or activation of a vagal reflex from the esophagus to the lungs causing bronchoconstriction. Animal and human studies report bronchoconstriction after esophageal acidification, but the response tends to be mild and unpredictable. In contrast, intratracheal infusion of even small amounts of acid induces profound and reproducible bronchospasm in cats. The reflux of acid into the trachea as compared with the esophagus alone predictably caused marked changes in peak expiratory flow rates in asthmatic patients. Although either mechanism may be responsible for reflux-induced asthma, most patients probably suffer from intermittent microaspiration.

Ear, Nose, and Throat Diseases

GERD may be associated with a variety of laryngeal conditions and symptoms, of which reflux laryngitis is perhaps the most common. These patients present with hoarseness, globus sensation, frequent throat clearing, recurrent sore throat, and prolonged voice warmup. Ear, nose, and throat signs attributed to GERD include posterior laryngitis with edema and redness, vocal cord ulcers and granulomas, leukoplakia, and even carcinoma. These changes usually are limited to the posterior third of the vocal cords and interarytenoid areas, both in close proximity to the upper esophageal sphincter. GERD is the third leading cause of chronic cough (after sinus problems and asthma), accounting for 20% of cases. Dental erosion, defined as the loss of tooth structure by chemical processes not involving bacteria, can be caused by GER in healthy persons and in patients with bulimia. Despite the association between ear, nose, and throat diseases and GERD, overt esophagitis usually is absent, and most patients have only mild reflux symptoms, if any. Microaspiration of gastric contents is the most likely cause of these complaints. Animal studies find that the combination of acid and pepsin is very injurious to the larynx. Human studies report that proximal esophageal acid exposure, especially at night while sleeping, is significantly increased in patients with laryngeal symptoms and signs.