We evaluated the mechanisms of gastroesophageal reflux in 10 patients with reflux esophagitis and compared the results with findings from 10 controls. The patients had more episodes of reflux (35 +/- 15 in 12 hours, as compared with 9 +/- 8 in the controls) and a lower pressure of the lower esophageal sphincter (13 +/- 8 mm Hg as compared with 29 +/- 9 in the controls) (P less than 0.001). Reflux occurred by three different mechanisms: transient complete relaxation of the lower esophageal sphincter, a transient increase in intra-abdominal pressure, or spontaneous free reflux associated with a low resting pressure of the lower esophageal sphincter. In controls 94 per cent of reflux episodes were caused by transient sphincter sphincter relaxation. In the patients 65 per cent of episodes of reflux accompanied transient sphincter relaxation, 17 per cent accompanied a transient increase in intra-abdominal pressure, and 18 per cent occurred as spontaneous free reflux. The predominant reflux mechanism in individual patients varied: some had normal resting sphincter pressure and reflux that occurred primarily during transient sphincter relaxation, whereas others with low resting sphincter pressures had spontaneous free reflux or reflux that occurred during an increase in intra-abdominal pressure.

A B S T R A C T We investigated the mechanism of gastroesophageal reflux (GER) in 10 healthy volunteer subjects. Continuous recordings of intraluminal esophageal pH and pressure were obtained on two consecutive nights from 6:00 p.m. to 6:30 a.m. in each subject. During each study, the subject remained recumbent, except to eat a standardized meal after 1 h of basal recording. A manometric assembly with seven recording lumens monitored: (a) lower esophageal sphincter (LES) pressure via a sleeve device 6.5 cm in length, (b) esophageal-body motor activity, (c) swallowing activity in the pharynx, and (d) gastric pressure. An electrode 5 cm above the LES recorded esophageal pH. Sleep was monitored by electroencephalogram. All subjects showed wide variations ofbasal LES pressure. GER was not related to low steady-state basal LES pressure, but rather occurred during transient 5-30 s episodes of inappropriate complete LES relaxation. The inappropriate LES relaxations were usually either spontaneous or immediately followed appropriate sphincter relaxation induced by swallowing. The majority of GER episodes occurred within the first 3 h after eating. During the night LES relaxation and GER occurred only during transient arousals from sleep or when the subjects were fully awake, but not during stable sleep. After GER the esophagus was generally cleared of refluxed acid by primary peristalsis and less frequently by secondary peristalsis. Nonperistaltic contractions were less effective than peristalsis for clearing acid from the esophagus. We conclude that in asympto-A preliminary communication of this work was abstracted in 1978 (Gastroenterology. 74: 1119.) and was presented at the

Our goals in this study were to evaluate the mechanisms operative in swallow-associated opening of the upper esophageal sphincter (UES) and to determine the dynamics of fluid flow across the sphincter. For this purpose, we obtained concurrent videofluorographic and manometric studies of 2- to 30-ml barium swallows in 15 normal subjects. We found that the resting UES high-pressure zone corresponded closely with the location of the cricopharyngeus. The findings indicated that manometric UES relaxation and anterior hyoid traction on the larynx invariably preceded UES opening. With graded increases in bolus volume, progressive increases occurred in UES diameter, cross-sectional area, flow duration, and transsphincteric flow rate. Intrabolus pressure upstream to the UES and within the UES at its opening during transsphincteric flow of barium remained within a narrow physiological range of less than 10 mmHg up to a bolus volume of 10 ml. With increases in bolus volume, anterior hyoid movement, UES relaxation, and UES opening occurred sooner in the swallow sequence to accommodate the early entry of large boluses into the pharynx. We conclude that during swallowing 1) normal UES opening involves sphincter relaxation, anterior laryngeal traction, and intrabolus pressure, 2) volume-dependent adaptive changes in UES dimension accommodate large bolus volumes and flow rates with minimal requirement for increases in upstream, or intrasphincteric, intrabolus pressure or UES opening duration, and 3) volume-dependent changes in UES dimensions as well as timing of UES relaxation and opening indicate a sensory feedback mechanism that modulates some components of the swallow response generated by the brain stem swallow centers.

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