Upper esophageal sphincter (UES) function during gastroesophageal reflux events is not completely elucidated because previous studies addressing this issue yielded conflicting results. We reexamined the UES pressure response to intraluminal esophageal pressure and pH changes induced by reflux events. We studied 14 healthy, asymptomatic volunteers (age 49 +/- 6 yr) and 7 gastroesophageal reflux disease patients (age 48 +/- 5 yr). UES pressure, intraesophageal pressure, and pH were monitored at the distal, middle, and proximal esophagus concurrently in the supine position 1 h before and 2 h after a 1,000-calorie meal. A total of 321 reflux events were identified by the development of abrupt reflux-induced intraesophageal pressure increase (IPI); 285 events occurred in patients and 36 in control subjects. In control subjects 33 of 36 and in patients 252 of 285 IPI events were associated with a pH drop. Among patients and control subjects, 99% and 100%, respectively, of all IPI events irrespective of pH drop were associated with abrupt increase in UES pressure (34 +/- 2 and 27 +/- 6 mmHg, respectively). The average percentage of maximum UES pressure increase over prereflux values ranged between 66% and 96% (control subjects) and 34% and 122% (patients). IPIs induced by both acidic and nonacidic reflux events evoke strong UES contractile responses.

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Radial asymmetry of the upper oesophageal sphincter high-pressure zone (UESHPZ) is an accepted notion based on manometric studies. Our aim was to evaluate the effect of the catheter diameter and configuration on the resting pressure profile of the UES. We studied 14 young (30 +/- 2 years) and 14 healthy elderly volunteers (77 +/- 2 years) using the station pull-through technique. We used a specially designed water perfused manometric assembly that incorporated a proximal round cross-section (4.8 mm) and a distal flat cross-section (4.8 x 1.2 mm). Anterior and posterior manometric sites on the round catheter measured significantly higher pressure values than did the sites oriented laterally at the same level (P < 0.001) in both young and elderly. In contrast, the flat-shaped catheter measured statistically indistinguishable pressures from all four orientations in both age groups. In both young and elderly the anterio-posterior, but not lateral pressures by the round catheter were significantly higher (P < 0.001) than those of the flat catheter. An exaggerated anteriorly and posteriorly oriented pressure may be recorded compared with lateral pressures depending on the diameter and non-conforming shape of the recording catheter with respect to the UES producing the appearance of radial asymmetry in the UESHPZ.

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