Esophagopharyngeal acid regurgitation: dual pH monitoring criteria for its detection and insights into mechanisms

BACKGROUND & AIMS

A valid technique for the detection of esophagopharyngeal acid regurgitation would be valuable to evaluate suspected reflux-related otolaryngologic and respiratory disorders. The aim of this study was to derive pH criteria that optimally define esophagopharyngeal acid regurgitation and to examine patterns of regurgitation.

METHODS

In 19 healthy controls and 15 patients with suspected regurgitation, dual or quadruple pH sensors were used to monitor pharyngeal and esophageal pH. For each combination of the 2 variables, DeltapH and nadir pH, proportions of pH decreases that occurred during or independent of esophageal acidification were calculated to determine the likelihood that an individual pharyngeal pH decrease was a candidate regurgitation event or a definite artifact.

RESULTS

Overall, 92% of pharyngeal pH decreases of 1-2 pH units and 66% of pH decreases of this magnitude reaching a nadir pH of <4 were artifactual. Optimal criteria defining a pharyngeal acid regurgitation event were a pH decrease that occurred during esophageal acidification, had a DeltapH of >2 units, and reached a nadir of <4 units in less than 30 seconds. Regurgitation occurred more frequently in subjects in an upright (32 of 35) than in a supine (3 of 35 events; P </= 0.0001) position and was more frequently abrupt (synchronous with esophageal acidification) than delayed (P </= 0.05).

CONCLUSIONS

Accepted criteria for gastroesophageal reflux are not applicable to the detection of esophagopharyngeal acid regurgitation, and most regurgitation occurs abruptly and in upright position.

Temperature dependence of responses of esophageal smooth muscle to electrical field stimulation

Strips of smooth muscle, cut transversely from the smooth-muscle segment of opossum esophagus, were superfused with oxygenated Krebs-Ringer solution at 37 degrees C in a system that allowed electrical field stimulation of the intrinsic nerves. Three-to-five-second trains of rectangular pulses (0.5 ms long at 10 Hz) were delivered at 30-s intervals at supramaximal maximal current strength. In strips from the esophageal body, each train resulted in a twitch which followed after the end of train with a particular latency, the off-response. Strips from the esophagogastric sphincter relaxed during the train. Temperature was varied above and below 37 degrees C to observe the temperature dependence of the responses. Latency of the off-response varied exponentially with temperature. Amplitude of the off-response showed a linear decline with changes in temperature, both above and below 35 degrees C, the zero-intercepts being 19.6 and 42.3 degrees C, respectively. Amplitude of relaxation of strips from the junction varied little between 20 and 37 degree C but declined sharply beyond those limits, the zero-intercepts being 14.2 and 42 degrees C, respectively.

Arterial vasoconstrictor therapy for bleeding oesophageal varices

Upper gastrointestinal bleeding in patients with hepatic cirrhosis carries considerable mortality. Difficulties are encountered both in determining the source of bleeding and in controlling blood loss. The techniques of selective visceral angiography not only supply diagnostic information, but can be used to administer selective intra-arterial vasoconstrictor therapy to control blood loss. We report our experience with 28 patients in whom angiography was performed with particular reference to six patients treated with selective vasoconstrictor therapy. Although the precise role of the technique is not yet established, early experience is most promising. We believe it will play an important role in a difficult group of patients in the future and may well supplant present methods of controlling bleeding.

Experimental gastroesophageal reflux in the Australian brush-tailed possum

It has been suggested that the lower esophageal sphincter (LES) plays an important role in preventing gastroesophageal reflux. This study was designed to determine if abolition of the LES alone is sufficient to induce gastroesophageal reflux and esophagitis. Studies were performed in the Australian brush-tailed possum (Trichosurus vulpecula) which has a lower esophagus resembling that of man. Esophageal manometry, esophagoscopy, and contrast radiography of the lower esophagus and stomach were performed before and after surgery in a group of animals undergoing cardioplasty and in a group of sham operated control animals. In the animals undergoing cardioplasty, LES pressure fell from a preoperative level of 12.6 +/- 1.3 mm Hg to 0 mm Hg. This was followed by the development of gastroesophageal reflux and esophagitis. Sham operation did not alter LES pressure or result in either gastroesophageal reflux or esophagitis. In 4 of 5 animals undergoing cardioplasty, LES activity returned after 10 weeks, and this time gastroesophageal reflux ceased and esophagitis healed. It is concluded that abolition of the LES alone can induce gastroesophageal reflux and esophagitis.