The determinants of the lower esophageal sphincter relaxation response to esophageal distension have not previously been systematically examined in humans. In this study, 14 healthy subjects were tested using a manometry catheter with a sleeve device and three balloons spaced 5 cm apart. Subjects had up to five distensions with each balloon at four different diameters and two different durations of inflation. The results indicated that 1,170 separate distensions were available for analysis. Sphincter relaxation occurred more frequently (P < 0.005) with larger balloon diameters, yet occurred in only 84% of inflations at the largest diameter. Sphincter relaxation was more often observed with the proximal balloon (P < 0.005) during longer distensions (P < 0.05) and when esophageal contractions occurred above the balloon (P < 0.005). Once sphincter relaxation occurred, its magnitude was essentially independent of balloon site and diameter, distension duration, and the presence of proximal contractions. In conclusion, even large balloon distensions do not uniformly produce or maintain lower esophageal sphincter relaxation. Sphincter relaxation is more likely with proximal esophageal distension. The association of sphincter relaxation with vagally mediated proximal contractions suggests vagal modulation of this response.
Abstract 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 × 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.
The frequency characteristics and wave form of peristaltic pressure complexes occurring in the pharynx and esophagus of normal subjects were studied. For each of five subjects, five peristaltic waves were selected for analysis from the proximal and distal pharynx as well as the proximal, middle, and distal esophagus. Thus, 25 peristaltic waves were analyzed from each of the five regions studied, giving a total of 125 in all. After digitization of the peristaltic waves, pressure values were entered into a computer algorithm that performed a Fourier transformation to determine frequency content and wave slope. The computer analysis revealed that a frequency response flat to 5 Hz was adequate to record 98% of esophageal peristaltic waves with 98% accuracy. In contrast, recording accuracy up to 48 Hz was needed for high-fidelity recording in the pharynx. Rates of pressure change were substantially greater for pharyngeal peristaltic pressure complexes compared with esophageal peristaltic complexes. The results suggest that appropriately designed infused-catheter systems can readily meet the requirements for accurate recording of peristaltic pressure waves in the esophagus but not in the pharynx. Consequently, different instrumentation, such as an intralum-inal strain gauge probe, is needed for accurate manometric recording of pharyngeal peristalsis.
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