Accurate placement of the esophageal pH electrode for 24-hour pH monitoring using a combined pH/manometry probe

Vitamin C reduces gastric pH in pharmacologically induced hypochlorhydria: a potential approach for mitigating pH-dependent drug-drug interactions of weak-base drugs

Orally administered, poorly soluble, weak-base drugs are subject to gastric pH-dependent drug-drug interactions which can be clinically significant. Proton pump inhibitors (PPIs) have been shown to reduce the bioavailability of kinase inhibitors, antivirals and triazole antifungals, through elevation of gastric pH. The objective of this study was to determine if chewable ascorbic acid (AA) tablets can induce a transient reduction in gastric pH. Healthy volunteers were pretreated with 20 mg omeprazole to induce hypochlorhydria. On the study day, gastric pH was continuously monitored using a catheter-based pH monitoring system. A pH electrode was transnasally placed in the stomach fundus and pH data was collected in real time. 1000 mg AA chewable tablets were ingested by the study participants with 240 mL of water. In five out of six subjects, a significant drop in gastric pH was observed. A mean (± SD) drop in pH of 3.7 (± 1.8) upon AA intake was observed and time taken to reach lowest gastric pH was 91.2 (± 64) min. Area under the pH versus time curve (AUCpH), below median pH over 15 min duration before AA intake, was determined to be 186.8 ± 136.7 (ΔpH.min). This pilot study demonstrates that 1000 mg of AA tablets can significantly reduce gastric pH in individuals receiving treatment with PPIs, providing a potential approach for mitigating pH-dependent drug-drug interactions of weak-base drugs.

Automated Test Assembly for Multistage Testing With Cognitive Diagnosis

Computer multistage adaptive test (MST) combines the advantages of paper and pencil-based test (P&P) and computer-adaptive test (CAT). As CAT, MST is adaptive based on modules; as P&P, MST can meet the need of test developers to manage test forms and keep test forms parallel. Cognitive diagnosis (CD) can accurately measure students' knowledge states (KSs) and provide diagnostic information, which is conducive to student's self-learning and teacher's targeted teaching. Although MST and CD have a lot of advantages, many factors prevent MST from applying to CD. In this study, we first attempt to employ automated test assembly (ATA) to achieve the objectives of MST in the application of CD (called CD-MST) via heuristic algorithms. The mean correct response probability of all KSs for each item is used to describe the item difficulty of CD. The attribute reliability in CD is defined as the test quantitative target. A simulation study with the G-DINA model (generalized deterministic input noisy "and" gate model) was carried out to investigate the proposed CD-MST, and the results showed that the assembled panels of CD-MST satisfied the statistical and the non-statistical constraints.

Clinical Assessment of Gastrointestinal Involvement in Patients with Systemic Sclerosis

Systemic sclerosis (SSc) has the potential to affect any component of the gastrointestinal (GI) tract. GI involvement in SSc is a leading cause of morbidity and overall decreased quality of life in this patient population, identifying a need for a concise approach to work-up. This literature review aims to present a systematic, anatomical approach and differential diagnosis of GI involvement in SSc for the general internist and rheumatologist. Each component of the luminal GI tract has its own specified section, beginning with a review of a clinical approach to diagnosis that includes a differential for clinicians to consider, followed by a discussion of the literature surrounding objective evaluation of these conditions (i.e. serologic studies, imaging, endoscopy). Additionally there is a focused discussion on an approach to GI bleeding in the patient with SSc.

Early referral for esophageal pH monitoring is more cost-effective than prolonged empiric trials of proton-pump inhibitors for suspected gastroesophageal reflux disease

INTRODUCTION

The most cost-effective diagnostic algorithm for gastroesophageal reflux disease (GERD) remains controversial. We hypothesized that prompt referral for esophageal pH monitoring is more cost-effective than prolonged empiric courses of proton-pump inhibitors (PPIs).

DISCUSSION

A cost model was created based on a cohort of 100 patients with possible GERD who underwent pH monitoring. The additional costs incurred from pH monitoring were compared to the potential savings from avoiding unnecessary PPI usage in patients with a negative pH study. The costs of PPI therapy reach equivalence with pH monitoring after 6.4 to 23.7 weeks, depending on the PPI regimen. A total of 21,411 weeks of PPIs were prescribed beyond the recommended 8-week trial, of which 32 % were for patients who had a negative 24-h pH monitoring study. If the sensitivity of pH monitoring was 96 %, early referral for pH monitoring would have saved between $1,197 and $6,303 per patient over 10 years. This strategy remains cost-effective as long as the sensitivity of pH monitoring is above 35 %. Prompt referral for pH monitoring after a brief empiric PPI trial is a more cost-effective strategy than prolonged empiric PPI trials for patients with both esophageal and extraesophageal GERD symptoms.

Determination of pH turning point with pH mapping of the gastroesophageal junction: an alternative technique to orientate esophageal pH monitoring

Manometric location of the lower esophageal sphincter (LES) has been mandatory before esophageal pH monitoring, despite costs and discomfort related with esophageal manometry. The aims of the study were: (i) to map the pH of the gastroesophageal junction (GEJ) to determine a pH turning point (PTP) and its relation with LES; and (ii) to test the feasibility of this technique to orientate esophageal pH monitoring. We studied 310 adult patients who underwent esophageal manometry and pH monitoring off acid-suppressive therapy. GEJ pH mapping was carried out by step-pulling the pH sensor from 5 cm below to 5 cm above LES, and a PTP was determined when pH changed from below to above 4, in centimeters from the nostril. Thirty-six patients referred only for pH monitoring were studied with pH sensor placed at 5 cm above the PTP. Out of 310 patients, a PTP was found in 293 (94.5%): inside LES in 86.3%, into the stomach in 8.2% and in the esophageal body in 5.5% of patients. The median distance between PTP and place where pH sensor monitored reflux was 8 cm. Among 36 patients who performed pH monitoring without LES manometry, there was no gastric monitoring during reflux testing. In adult patients investigated off acid suppressive therapy, GEJ pH mapping with reflux monitoring 5 cm above the PTP can be an alternative technique to perform esophageal pH monitoring when LES manometry is not available. Additional studies are needed before the widespread use of GEJ pH mapping in the clinical practice.

Esophageal impedance monitoring for gastroesophageal reflux

Dual pH-multichannel intraluminal impedance (pH-MII) is a sensitive tool for evaluating overall gastroesophageal reflux disease, and particularly for permitting detection of nonacid reflux events. pH-MII technology is especially useful in the postprandial period or at other times when gastric contents are nonacidic.pH-MII was recently recognized by the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition and the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition as being superior to pH monitoring alone for evaluation of the temporal relation between symptoms and gastroesophageal reflux. In children, pH-MII is useful to correlate symptoms with reflux (particularly nonacid reflux), to quantify reflux during tube feedings and the postprandial period, and to assess efficacy of antireflux therapy. This clinical review is simply an evidence-based overview addressing the indications, limitations, and recommended protocol for the clinical use of pH-MII in children.

The transnasal esophagoscopy documentation dilemma

OBJECTIVE

To determine radiographically the anatomic length difference between the nasal and oral aerodigestive tracts and to clarify gaps in the literature regarding standardized landmark measurements and documentation techniques in transnasal esophagoscopy, as opposed to traditional transoral esophagoscopy.

STUDY DESIGN

This is a prospective radiographic cohort study.

METHODS

Digital computerized tomography measurement techniques were used to determine the difference in length between the nasal and oral aerodigestive tracts. Using sagittal plane images from consecutive patients, the mean nares-cricoid (NC) distance, upper incisor-cricoid (IC) distance, and their mean differences were determined. Male, female, and overall distances and differences were calculated. Standard deviations, 95% confidence intervals, and 90% prediction intervals were also calculated. Mean difference data were applied to reported standard oral esophagoscopy landmark measurements to convert to standard landmark measurements from the nares.

RESULTS

Overall mean NC and IC distances were 175.4 mm and 147.5 mm, respectively. For males, these mean distances were 185.5 mm and 155.0 mm, respectively. For females, these mean distances were 165.3 mm and 140.0 mm, respectively. Overall mean NC to IC difference was 27.9 mm. The mean NC to IC difference for males and females was 30.5 mm and 25.2 mm, respectively.

CONCLUSIONS

Historically, landmark and report measurements in esophagoscopy have been measured and standardized from the upper incisor. This study demonstrates and clarifies the inherent anatomic length difference of the nasal and oral aerodigestive tracts and the resultant documentation dilemma produced by transnasal esophagoscopy techniques. These data provide easy conversion of esophagoscopy measurements reported from the incisors or nares, providing better communication between endoscopists of different disciplines and techniques.

Comparison of air-coupled balloon esophageal and anorectal manometry catheters with solid-state esophageal manometry and water-perfused anorectal manometry catheters

Clinical gastrointestinal manometry studies are currently performed with multilumen water-perfused polyvinyl or strain gauge sensor solid-state catheters. A disposable catheter incorporating air-filled balloons has been developed with performance characteristics suitable for esophageal and anorectal manometry studies. Our aim was to compare esophageal and anorectal pressure measurements using this newly developed catheter with measurements obtained using standard solid-state or water-perfused catheters. Measurements of resting LES pressure, esophageal contraction amplitudes, and anorectal rest and squeeze pressures were obtained in 10 healthy volunteers using a solid-state esophageal catheter, a water-perfused anorectal catheter, and air-filled balloon esophageal and anorectal catheters. Correlation coefficient analysis demonstrated that LES pressures, esophageal contraction amplitudes, and anorectal resting and squeeze pressures were not significantly among between the different catheters. We conclude that recently developed air-filled balloon esophageal and anorectal manometry catheters provide very similar measurements of LES, esophageal body, and anorectal sphincter pressures compared to presently used manometry catheters.

Use of radioisotopic esophageal transit in the assessment of patients with symptoms of reflux and non-specific esophageal motor disorders

The purposes of this study were to assess the esophageal clearance of a radioisotopic bolus in patients with symptoms of reflux and evaluate the impact of manometric abnormalities on scintigraphic esophageal transit. Esophageal clearance was assessed in a supine position and indicated by the retained radioactivity in the esophagus at 10, 20, 30 and 40 s after the ingestion of a liquid bolus labeled with 2 mCi 99 mTc-SC. The study included 214 consecutive patients with symptoms of reflux and 11 normal controls. The results were compared to the motility findings detected on manometry performed on a separate occasion. Esophageal manometry was normal in 93 patients. Nonspecific esophageal motor disorders were identified in 121 patients and were classified into: 'predominantly nonpropagated activity', 'predominantly low-amplitude peristaltic contractions' and 'miscellaneous disorders' diagnosed in 27, 47 and 47 patients, respectively. The radionuclide clearance was significantly delayed in the overall group of patients compared with that of normal controls (P < 0.001); in patients with reflux symptoms and nonspecific esophageal motor disorders compared with patients with reflux symptoms and 'normal manometry' (P < 0.01 at 20 s); and in patients with reflux symptoms and 'normal manometry' compared with the control group (P < 0.01 at 20 s). Abnormal radioisotope clearances were detected in 88% of patients with 'predominantly nonpropagated activity', in 70% of patients with 'predominantly low-amplitude peristaltic contractions' and in 57% of patients with 'miscellaneous disorders'. Radioisotopic esophageal clearance abnormalities are frequently observed in patients with reflux symptoms and are more likely to be associated to hypomotility disorders, i.e. nonpropagated motor activity or low-amplitude contractions.

pH probe positioning for 24-hour pH-metry by manometry or pH step-up

OBJECTIVES

Before pH measurement, manometry is recommended for precise pH probe positioning. We investigated whether the pH probe could be positioned accurately by the pH difference between the oesophagus and the stomach (pH step-up).

METHODS

Dual-channel 24-h pH-metry with probes positioned 5 cm above either the manometrically determined upper lower oesophageal sphincter margin or the pH step-up was performed in healthy volunteers and reflux patients. To determine the pH step-up, the pH probe was pulled back from the stomach until a sudden rise to pH greater than four occurred. Probe position, reflux episodes and the fraction of the time pH was less than four were compared using the Wilcoxon test for difference and the Hodges-Lehman estimate inclusive confidence interval for equivalence. The pH step-up method was evaluated further during proton pump inhibitor therapy and after drug discontinuation.

RESULTS

The pH probe was positioned 2 cm and 1 cm closer to the stomach by the pH step-up method in the volunteers and reflux patients, respectively. A small increase in upright reflux episodes but not in supine reflux episodes was registered by the probe positioned by pH step-up. No significant differences in the fraction of the time pH was less than four were obtained between the two probes. The Hodges-Lehman calculation proved equivalence for both methods of probe positioning for 24-h pH-metry. During proton pump inhibitor therapy, no pH step-up was detectable in three volunteers and in one patient. On the first day after discontinuing therapy, the pH step-up method yielded clear-cut results again.

CONCLUSION

The pH probe for diagnostic 24-h pH-metry and, with some limitations, also for 24-h pH-metry for therapy control, can be positioned accurately by the pH step-up method.

A predictive model for length of Barrett's esophagus with hiatal hernia length and duration of esophageal acid exposure

BACKGROUND

A significant correlation between the duration and height of esophageal acid exposure and the length of Barrett's mucosa has been demonstrated. The aims of this study were to determine if there is a correlation between hiatal hernia length and Barrett's esophagus length, and to develop a predictive model for Barrett's esophagus length by using hiatal hernia length and duration of esophageal acid exposure.

METHODS

Consecutive patients with Barrett's esophagus diagnosed endoscopically were enrolled in the study. Barrett's esophagus was defined by the presence of intestinal metaplasia in biopsy specimens obtained from salmon-colored mucosa extending into the esophagus. Barrett's mucosa 3 cm or greater in length was considered long-segment Barrett's esophagus; and less than 3 cm long was considered short-segment Barrett's esophagus. Hiatal hernia was considered present if the esophagogastric junction was displaced 1 cm or more proximal to the diaphragmatic hiatus.

RESULTS

Twenty-four men (mean age 66.1 +/-2.4 [SE]) with Barrett's esophagus were included in this study. Mean Barrett's length was 4.1 +/-0.7 cm. The Pearson correlation coefficient between hiatal hernia length and Barrett's esophagus length was 0.62 (p < 0.01). Similarly, there was a significant correlation between esophageal acid exposure and Barrett's length (r = 0.62; p < 0.01). Multiple linear regression analysis revealed that hiatal hernia length and duration of esophageal acid exposure were associated significantly with length of Barrett's mucosa (R(2) = 0.54; p < 0.001). A regression equation was developed expressing mean Barrett's length (cm) = 0.79 + (0.68) hernia length (cm) + (0.075) duration of esophageal acid exposure (% time pH < 4).

CONCLUSIONS

The length of Barrett's mucosa correlated with the length of hiatal hernia. A predictive model for Barrett's length by using hiatal hernia length and duration of esophageal acid exposure was developed. This suggested that these two pathophysiologic factors are good predictors of the length of Barrett's mucosa.

Which is the better method for location of the gastro-esophageal junction: radiography or manometry?

PURPOSE

To evaluate whether location of the gastro-esophageal junction (GEJ) could be determined with the same accuracy on radiography as by manometry with special reference to pH probe positioning.

MATERIAL AND METHODS

Ninety patients with suspected esophageal motility disorders underwent simultaneous manometry and video-radiography. The lower esophageal sphincter pressure (LESP) and location was determined, and pressure recordings were made in the body of the esophagus. The GEJ and any structural changes were diagnosed on radiography during single-barium swallows and continuous barium drinking. Simultaneous radiographic and manometric investigations were performed with the pressure-catheter placed 5 cm proximal to the superior border of the GEJ located by manometry, and the distance to the radiographically determined superior border could be measured directly on the videotapes using a radiopaque metric ruler placed under the patient.

RESULTS

On radiography, the GEJ proved to be situated < 2 cm distally as compared to its location determined by manometry in 95.6% of the patients, and the maximal difference was 2.5 cm. The LESP or structural changes had no significant influence on the results.

CONCLUSION

The variation of location of GEJ on radiography as compared with manometric findings was sufficiently small to accept both methods as valid in the positioning of the pH probe properly.

Esophageal motor disorders

Esophageal motor function remains of investigative and clinical interest because of its relevance to symptoms and its relation to the occurrence and management of gastroesophageal reflux disease. Refinement in diagnostic methods continues to occur, and improved tests for identifying the nature or severity of motor disturbances in both the proximal and distal esophageal regions are now well described. Controversy concerning the management of achalasia, the best-understood distal motor disorder, is resolving as the benefits and disadvantages of available treatment options are becoming recognized. The relation of esophageal motor dysfunction to outcomes from antireflux surgery remains incompletely understood.