Pressure exposure and catheter impingement affect the recorded pressure in the Manoscan 360™ system.

BACKGROUND: The accuracy of pressure measurements by Manoscan high-resolution manometry (HRM) system is affected by pressure drift (PD). The PD is partly related to temperature and study duration, but other factors that contribute to errant pressure recording have not been systematically evaluated. The aim of this study was to investigate and quantify contributing factors to pressure recording error. METHODS: In total, 660 in vitro experiments were conducted on seven HRM catheters to determine the effects of sustained pressure exposure, catheter impingement, temperature, duration of study, and immersion in saline or acid on recorded pressure and PD. KEY RESULTS: At room temperature and without application of pressure, the PD was negligible. Application of sustained pressure significantly increased PD and catheter impingement of even 15° produced remarkable increases in the recorded pressure as well as post-recording PD. There was significant variability across sensors in their propensity to develop PD with temperature. Body (37°C) and freezing (0°C) temperatures resulted in significantly higher absolute value of PD in the opposite algebraic direction, respectively (for individual sensors). Although the overall trend was for higher PD with increasing temperature, some of the pressure sensors demonstrated inherently negative PD at body temperature. CONCLUSIONS AND INFERENCES: In addition to the known effects of temperature, both sustained pressure exposure and catheter impingement significantly affect the recorded pressure and the magnitude of the PD observed at the end of the recording. These effects can be substantial enough to result in erroneous manometric diagnoses.

Determinants of pressure drift in Manoscan(™) esophageal high-resolution manometry system.

BACKGROUND: Manoscan(™) is one of the commonly used high-resolution manometry (HRM) systems with declared measurement accuracy of 1-2 mmHg. However, the accuracy of pressure measurements is limited by development of pressure drift (PD) throughout recording. To date, there has been no systematic investigation to identify the factors contributing to PD. The aim of the present study was to characterize the frequency and magnitude of PD in Manoscan(™) system and identify the factors contributing to PD. METHODS: Records of 560 consecutive clinical esophageal HRM studies recorded by six distinct HRM catheters were retrospectively reviewed. PD was defined as the residual pressure measurement by each sensor immediately after removal of the catheter. Non-parametric locally weighted regression analysis was performed to assess the effect of duration of study, number of prior uses of a catheter, peak and average pressure exposure during a study on the PD. KEY RESULTS: The majority (95%) of clinical manometry studies showed a non-negligible PD of more than 5 mmHg. The overall PD was 13 ± 5 mmHg and the sensor with greatest amount of PD showed 23 ± 12 mmHg of drift. The upper esophageal sphincter showed the highest PD. Average pressure exposure of a sensor throughout the recording was the most important predictor of PD. PD inversely correlated with number of prior uses of a catheter. CONCLUSIONS & INFERENCES: The PD preferentially affects esophageal high-pressure zones, and strongly correlates with 'average pressure exposure' of a sensor during manometry. Available algorithms of the analysis software do not adequately correct the PD.

Radial asymmetry of the upper oesophageal sphincter pressure profile: fact or artefact.

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.

Potential control of gastroesophageal reflux by local modulation of transient lower esophageal sphincter relaxations.

Transient lower esophageal sphincter relaxations (TLESRs) are neurally mediated abrupt reductions in lower esophageal sphincter (LES) pressure. TLESRs are not usually associated with deglutition or secondary peristalsis but are thought to be necessary for venting swallowed air from the stomach. Their central role in acid reflux, however, makes them a compelling therapeutic target for patients with gastroesophageal reflux disease. Pharmacologic approaches for reducing TLESR frequency are being studied, but theoretically more promising are endoscopic approaches that interfere with mechanoreceptor function. Further study into the mechanisms of action of these approaches is needed, as are controlled clinical trials to define the true utility of these techniques and identify patients who will receive the most benefit.

Management of idiopathic achalasia: short-term and long-term outcomes.

This article reviews current trends in management of esophageal achalasia, highlighting short-term outcome and cost comparisons of three treatments: botulinum toxin injection, pneumatic dilation, and laparoscopic myotomy. The quality of life resulting from these palliative treatments is also discussed, as are long-term outcomes.

Discrete ulcers in Barrett's esophagus: relationship to acute gastrointestinal bleeding.

BACKGROUND AND STUDY AIMS: Although discrete ulcers are a recognized complication of Barrett's esophagus, it is not clear how common discrete ulceration is in Barrett's mucosa. Furthermore, the relationship of gastrointestinal hemorrhage to Barrett's ulceration is unknown. These issues were investigated in this paper. METHODS: Seventy-eight patients with histologically confirmed Barrett's esophagus were monitored by endoscopic surveillance over 1 to 11 years (mean 3.3 years). The incidence of a Barrett's ulcer was noted and its site recorded. The frequency of gastrointestinal hemorrhage at diagnosis or on follow-up was documented and the source of the bleeding was identified. RESULTS: Discrete ulcers were identified in 36 of 78 patients (46%) at some time over the period of follow-up. Eight patients had two or more ulcers. Most of ulcers were in the distal esophagus; 86% of these were within 3 cm of the anatomic gastroesophageal junction. Nineteen patients (24%) either presented with active gastrointestinal bleeding or had bleeding at follow-up. In 15 of the 19 patients with bleeding (79%) a discrete Barrett's ulcer was the source of the hemorrhage. CONCLUSIONS: Ulceration is a common complication of Barrett's esophagus. These ulcers are usually located close the gastroesophageal junction and have a high incidence of bleeding.

Initiation of esophageal secondary peristalsis by slow fluid infusion in the opossum: effect of hydrochloric acid.

We investigated the mechanisms of slow fluid infusion-induced secondary peristalsis and the effects of hydrochloric acid on this response. In 13 chronically esophagostomized opossum, acidic and neutral barium sulfate were infused into the distal esophagus at a rate of 1.1 ml/min, while recording the esophageal dimension by videofluoroscopy and esophageal intraluminal pressure concurrently. The effects of atropine, tetrodotoxin, capsaicin, and bilateral cervical vagotomy on the response to slow fluid infusion were examined. Acidic barium initiated secondary peristalsis more frequently and at shorter latency with less increase of preperistaltic intraesophageal pressure than neutral barium (P < 0.05). Atropine abolished secondary peristalsis initiated by neutral barium. For acidic barium, atropine decreased the incidence of secondary peristalsis, increased the latency for initiation of secondary peristalsis, and initiated secondary peristalsis more distally (P < 0.05). Tetrodotoxin or vagotomy and capsaicin abolished activation of secondary peristalsis. We concluded that secondary peristalsis can be stimulated in response to slow distension by minute amounts of fluid. This peristalsis is atropine and capsaicin sensitive and vagally mediated. The presence of acid significantly lowers the threshold for stimulation of secondary peristalsis induced by slow fluid distension. This effect seems to be atropine resistant.

Determinants of lower esophageal sphincter relaxation induced by esophageal balloon distension in humans.

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.

Pathological pharyngo-esophageal interactions.

Because of their normally coordinated function and physical contiguity, the pharynx and esophagus are subject to pathologic interactions in various disease or iatrogenic states. A useful conceptualization of these pathologic interactions is that of abnormal bolus transport. Specific clinical examples are given in which abnormal pharyngo-esophageal interactions appear to result in abnormal bolus transport, with its attendant consequences.

Cytomegalovirus infection causing pseudomembranous colitis.

A liver transplant patient with previous episodes of diarrhea and pseudomembranous colitis due to Clostridium difficile subsequently developed pseudomembranous colitis due to cytomegalovirus. The patient responded to ganciclovir. Cytomegalovirus infection should be considered in the differential of pseudomembranous colitis in immunocompromised patients, particularly when C. difficile toxin assays or cultures are negative.

Hospital discharges resulting from esophagitis among Medicare beneficiaries.

Despite the frequent occurrence of gastroesophageal reflux disease, until now only very few studies have dealt with the epidemiology of this common disorder. The Health Care Financing Administration complies annually 10 million records of all hospital discharges among Medicare beneficiaries distributed throughout the United States. The purpose of the present study was to take advantage of this large data set and analyze the demographic characteristics of patients discharged with esophagitis, esophageal ulcer, or esophageal stricture. The hospital discharge rates of all three diagnoses showed an age-related rise, the rise being most pronounced for esophageal stricture and, less significant, esophageal ulcer. The marked age dependency of esophageal stricture and ulcer may reflect the time necessary for complications to develop. While simple esophagitis affected women more frequently than men, significantly more men contracted its severe forms involving ulcers and strictures. All forms were more common in whites than blacks, and living in the southern parts of the United States was associated with an increased risk for esophagitis and strictures. The data suggest that besides varying exposure to environmental risk factors, differences in the pathophysiology among demographically stratified groups contribute to the occurrence of esophagitis.

Investigations of the regulation of specific 2-[125I]iodomelatonin binding sites in Siberian hamsters by endogenous and exogenous melatonin.

These studies used quantitative in vitro autoradiography to investigate whether endogenous or exogenous melatonin modulate specific 2-[125I]iodomelatonin binding sites in the pars tuberalis or suprachiasmatic nuclei of Siberian hamsters. Saturation analyses were conducted on tissue sections from hamsters that were pinealectomized, exposed to constant illumination (72 h), or injected with melatonin, and from hamsters that were treated as controls. High affinity (Kd approximately 20-75 pM) specific 2-[125I]iodomelatonin binding sites were detected in the suprachiasmatic nuclei and pars tuberalis of all animals. Neither pinealectomy nor constant illumination significantly affected either the affinity or the density of the specific 2-[125I]iodomelatonin binding sites in either region. Melatonin injections led to a decrease in specific 2-[125I]iodomelatonin binding to the pars tuberalis at 3-4 h after the last injection. However, washing the sections before incubation with 2-[125I]iodomelatonin eliminated this effect, suggesting that melatonin was occupying the binding sites rather than decreasing their actual number. Furthermore, when hamsters were sacrificed 18 h after the last melatonin injection, no effect of melatonin on either the affinity or density of specific 2-[125I]iodomelatonin sites was observed. These data suggest that 2-[125I]iodomelatonin binding sites in Siberian hamsters are not regulated by changes in circulating melatonin levels.

Determinants of intrabolus pressure during esophageal peristaltic bolus transport.

Previous manometric studies of esophageal fluid bolus transport in humans have generally ignored the hydrodynamic distinction between intrabolus pressure and pressure within the lumen-occluded, contracting esophageal segment. In this study we obtained concurrent esophageal videofluoroscopic and intraluminal manometric recordings in supine normal volunteers using different bolus volumes and viscosities and abdominal compression. Intrabolus pressure increased with bolus volume, viscosity, and abdominal compression. Esophageal diameter increased with larger bolus volumes, and this increase was correlated with increases in intrabolus pressure. Intrabolus pressure was highest in the bolus tail. Peak intraluminal pressures > 20 mmHg above basal intrabolus pressure almost invariably were associated with effective peristalsis, whereas values of this pressure differential < 20 mmHg frequently were associated with ineffective peristalsis and retrograde bolus escape. Intrabolus pressure can serve as an important indicator of the forces resisting peristaltic transport and the occurrence of ineffective bolus transport.

Epidemiology of hospitalization for achalasia in the United States.

Achalasia is an uncommon esophageal motility disorder of unknown etiology. To gain insights into possible etiologic risk factors, demographic and comorbidity data were obtained from Medicare hospital discharge data files from 1986-1989 on patients aged 65 and older. Age-adjusted sex- and race-specific occurrence rates were calculated for each US state. The rate of comorbid illness occurrence in achalasia patients was compared to that of the entire hospitalized Medicare population. Records of 15,000 achalasia discharges were available for analysis. Achalasia discharge rates increased linearly from age 65 to 94 years. They were similar in males and females as well as whites and nonwhites. High rates were observed in the South and low rates in most states of the East North Central region around the Great Lakes and in the Pacific region. The same geographic pattern was observed in men and women as well as in the two separate subsets of data representing the periods 1986-1987 and 1988-1989. Achalasia was associated with a significantly increased risk for pulmonary complications, malnutrition, and gastroesophageal cancer. The concordant occurrence of achalasia in patients with Parkinson's disease, depressive disorder, and various other myoneural disorders indicated a possible etiologic relationship. Achalasia appears to represent the clinical end point of several different pathways. Besides aging, different neurologic diseases may contribute to a loss in control of esophageal motility. The geographic pattern could suggest the influence of environmental factors.

The use of intraluminal manometry to assess upper esophageal sphincter function.

The UES is a striated muscular structure that exhibits substantial variation in tone in response to a wide variety of stimuli as well as during deglutition. It is an asymmetric structure subject to substantial axial movement. Hence the findings on UES manometry are highly dependent upon the manometry equipment used, positioning of this equipment in relation to the UES, and external stimuli. There is considerable intrasubject and intersubject variation in some parameters from UES pressure recordings. These factors must be taken into accout in the clinical use of UES manometry.

Alteration of the upper esophageal sphincter belch reflex in patients with achalasia.

Some patients with achalasia have been reported to develop airway obstruction from a massively air-distended esophagus, which may represent an abnormality in the upper esophageal sphincter belch reflex. When questioned carefully, 95% of our achalasia patients reported difficulty with belching. The upper esophageal belch reflex in 23 consecutive achalasia patients and 12 healthy controls was studied using an upper esophageal sphincter sleeve manometry catheter and rapid injection of 20-50 mL of air into the midesophagus. Compared with normal subjects, achalasia patients were significantly less likely to have an esophageal belch for all volumes tested and were more likely to have an increase rather than a decrease in upper esophageal sphincter pressure in response to air injection. This study systematically documents that many achalasia patients have an alteration in the upper esophageal sphincter belch reflex that may be a contributory mechanism for some of the chest and upper airway symptoms reported by some patients during acute esophageal distension.

Evaluation of a voice recognition system for generation of therapeutic ERCP reports.

We evaluated a computerized report-generating system using voice recognition technology (EndoSpeak) for producing therapeutic ERCP reports. For 30 consecutive ERCP cases, reports using both EndoSpeak and standard dictation were generated at the end of the procedure. The cases were scored for overall difficulty and the number of component procedures performed. The time to generate a report with EndoSpeak was significantly longer than with dictation (10.0 +/- 2.9 (SD) min vs. 6.5 +/- 1.6 min, p less than 0.0001), and this difference was greater for more lengthy reports (r = 0.85, p less than 0.001). The procedure difficulty score and the number of component procedures were both significant predictors of the physician's report generation time for EndoSpeak and dictation. Dictated reports were judged to have a higher information content than EndoSpeak reports for 90% of the cases (p less than 0.00001). Several specific difficulties were encountered with the EndoSpeak software. Although EndoSpeak offers promise, substantial software modifications will be required before this system can become competitive with dictation for therapeutic ERCP reports.

Abnormal esophageal motility. An analysis of concurrent radiographic and manometric findings.

The findings of concurrent esophageal videofluoroscopy and manometry in 15 patients with major disturbances of esophageal motor function were evaluated and the data were analyzed from a fluid mechanical perspective. Each of 153 fluoroscopic barium swallow sequences was analyzed on a swallow-by-swallow basis. Two distinct pressure domains were identified: intrabolus pressure and pressure within a bolus-free contracting esophageal segment. Analyses in terms of these pressure domains showed specific and consistent correlations between the radiographic and manometric findings. Radiography was insensitive to contractions occurring in esophageal segments devoid of bolus fluid, whereas manometry was insensitive to contractions that did not occlude the lumen. It is concluded that using fluid mechanical principles of bolus transport allows meaningful comparison of esophageal motility as recorded by radiography and intraluminal manometry. However, the inherent limitations in the range of physical phenomena recorded by each modality make these techniques complementary for evaluating esophageal motor function.

Effect of swallowed bolus variables on oral and pharyngeal phases of swallowing.

In this investigation, we studied the effects of bolus volume and viscosity on the quantitative features of the oral and pharyngeal phases of swallowing. Concurrent videofluoroscopic and manometric studies were done in 10 healthy volunteers who were imaged in lateral projection. Videofluorography was done at 30 frames/s while concurrent manometry was done with 5 intraluminal transducers that straddled the pharynx and upper esophageal sphincter (UES). Submental electromyography was recorded also. Swallows of 2-20 ml were recorded for low-viscosity liquid barium and high-viscosity paste barium. Analysis indicated that the major effect of increases in bolus volume was an earlier onset of anterior tongue base movement, superior palatal movement, anterior laryngeal movement, and UES opening. These events provide receptive adaptation for receiving a swallowed bolus. Earlier UES opening was associated with an increase in the duration of sphincter opening and sphincter diameter. The major effects of high bolus viscosity, unrelated to bolus volume, were to delay oral and pharyngeal bolus transit, increase the duration of pharyngeal peristaltic waves, and prolong and increase UES opening. Thus the specific effect of bolus viscosity per se differs substantially from that of bolus volume. We conclude that 1) specific variables of swallowing are affected significantly by the variables of the swallowed bolus, such as volume and viscosity; 2) overall, bolus volume and viscosity affect swallowing in a different manner; and 3) the study findings have implications about the neural control mechanisms that govern swallowing as well as about the diagnosis and treatment of patients with abnormal oral-pharyngeal swallowing.