Does body posture affect the incidence and mechanism of gastro-oesophageal reflux?

Article Abstract:

During normal digestion, ingested materials are propelled into the stomach by a wave of muscular contraction, passing through the cardiac (gastroesophageal) sphincter, which momentarily relaxes to allow passage. The highly acidic contents of the stomach are then prevented from entering the esophagus, where they would cause inflammation (esophagitis), by closure of the cardiac sphincter. In some cases, acid does manage to enter the esophagus from the stomach (gastroesophageal reflux), causing heartburn or, in more severe cases, physical damage to the esophageal mucosa. It is generally held that gastroesophageal reflux is more frequent when one is in a supine (as opposed to upright) position, resulting from the lack of opposing gravitational force. It is known that transient relaxation of the cardiac sphincter is the predominant cause of gastroesophageal reflux in the supine position. Recent evidence suggests that gastroesophageal reflux in the upright posture may be quite common, especially among patients suffering from reflux disease; the mechanism underlying this is not known. To investigate this issue, simultaneous determinations of esophageal acidity (pH) and pressure levels were performed in eight patients (equal numbers of men and women; average age 43 years) who had experienced daily heartburn for at least six months. Four of the patients had evidence of esophageal damage on endoscopy; two had normal esophageal mucosa, but had heightened sensitivity to esophageal acid. In this group of patients, the incidence of reflux was higher when patients were in the upright (compared with supine) position. In both positions, the predominant mechanism for allowing acid to enter the esophagus was transient relaxation of the cardiac sphincter. There were no differences in total reflux time (the time required to clear the acid from the esophagus) or number of episodes of greater than five minutes duration between the two positions. (Consumer Summary produced by Reliance Medical Information, Inc.)

Risk factors

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Sleep and nocturnal acid reflux in normal subjects and patients with reflux esophagitis

Article Abstract:

Esophagitis is an inflammatory disease of the esophagus, generally believed to result from excessive exposure to the highly acidic content of the stomach. The lower esophageal sphincter, which ordinarily prevents gastric contents from undergoing reflux into the esophagus, may relax inappropriately under certain circumstances allowing the caustic mixture of gastric acid and other stomach contents to come into contact with the mucosa (lining) of the esophagus. To determine whether acid reflux occurs more frequently at night in patients with esophagitis than in normal subjects, a study was conducted with 11 normal individuals and 11 patients suffering from esophagitis (well matched on relevant variables). After ingestion of a standard evening meal, all subjects were equipped with instruments to measure esophageal pressure, acidity, and to record sleep patterns. Patients with esophagitis had significantly more incidents of gastroesophageal reflux during the night than did normal subjects (105 versus 6). Of the 105 total occurrences of gastroesophageal reflux, 92 (88 percent) occurred while the subject was awake, 10 (9.5 percent) occurred during Stage II sleep (a nondream phase of the sleep cycle), and the remaining 2.5 percent occurred during other phases of the sleep cycle (Stage I, Stage III, and REM or rapid eye movement sleep). There were no differences in sleep patterns between the normal subjects and esophagitis patients. Many of the occurrences of reflux took place during brief periods of arousal from sleep. About half the episodes of gastroesophageal reflux resulted from transient relaxation of the lower esophageal sphincter; increased gastric pressure and other mechanisms accounted for the remainder. (Consumer Summary produced by Reliance Medical Information, Inc.)

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Alkaline reflux esophagitis

Article Abstract:

Esophagitis, also referred to as heartburn, is an inflammatory condition affecting the esophagus. Esophagitis is frequently caused by reflux of gastric and duodenal (upper intestinal) contents back into the esophagus. It is widely held that the acidic secretions of the stomach burn the esophagus upon reflux, which they are certainly capable of doing. However, the fact that patients suffering from achlorhydria (absence of gastric acid secretion) and patients who have undergone gastrectomy (stomach removal) may suffer from esophagitis speaks against the notion that only acidic secretions of the stomach can result in esophagitis. Recent research has revealed that not only gastric acid, but also pepsin (a digestive enzyme that is alkaline, or basic in nature) can cause esophagitis. In addition, bile salts (digestive compounds secreted by the liver into the intestine) are also capable of causing similar damage to the mucosa (lining) of the esophagus. An influential hypothesis concerning the etiology of esophageal lesions holds that certain destructive (nonacidic) substances produced by the body can have a synergistic effect, potentiating the inflammatory effects of gastric acid. This would explain why high doses of potent antisecretory drugs are capable of healing esophageal lesions in between 70 and 90 percent of patients (in the face of virtually complete suppression of gastric acid secretion); gastric acid is the most potent inducer of inflammatory damage to the esophagus, enhanced in many cases by other compounds, but not absolutely necessary for the production of damage. (Consumer Summary produced by Reliance Medical Information, Inc.)

Heartburn

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