The LES Locator: Accurate Placement of an Electrode for 24-Hour pH Measurement with a Combined Solid State Pressure Transducer

Twenty-four-hour esophageal pH monitoring is the gold standard for diagnosing gastroesophageal reflux disease. A possible limitation to the widespread use of this test is that manometry is required for accurate placement of the pH electrode 5 cm above the lower esophageal sphincter. We compared the accuracy of a single solid state pressure transducer, combined with a pH electrode, in determining the proximal border of the lower esophageal sphincter (LES) with the values obtained from stationary manometry in 40 patients referred to our laboratory for 24-h pH studies. Not only was there a strong correlation (r = 0.9) between LES values obtained by the two techniques, but none of the values obtained by the single solid state transducer were outside the clinically accepted range of greater than +/- 3 cm. The presence of a hiatal hernia or low sphincter pressure did not affect these measurements. The larger probe was tolerated somewhat less well (p = 0.02) than a standard antimony electrode during the prolonged pH studies. In conclusion, a single solid state pressure transducer on a pH probe with the help of a LES locator accurately identifies the proximal border of the LES. Therefore, stationary esophageal manometry is no longer needed prior to 24-h pH monitoring, potentially making this important clinical tool available to a wider variety of clinicians at all levels of the health care system, in investigating gastroesophageal reflux and its protean clinical presentations.     

Esophageal pH monitoring: are you sure that the electrode is properly placed?

OBJECTIVE: A crucial methodological aspect of ambulatory 24-h esophageal pH monitoring is electrode placement. Lower esophageal sphincter (LES) location is recommended for standard electrode positioning. The aim of the present study was to evaluate prospectively whether LES manometric location and intragastric pH acid confirmation suffice to guarantee that the pH electrode is properly placed. METHODS: We evaluated data from 402 consecutive patients undergoing esophageal pH monitoring. LES location was determined by manometry, and the pH electrode was introduced until a pH recording <3 was obtained. Subsequently, it was positioned 5 cm above the proximal LES border. Thereafter, adequate catheter placement and absence of bends or loops were checked by fluoroscopy. Patients with bent or rolled catheters were instructed to have breakfast immediately, and catheter placement was checked again by fluoroscopy. RESULTS: When checked by fluoroscopy, the catheter was properly placed in 383 patients (95.3%). In the other 19 (4.7%), it was not located in the distal part of the esophagus owing to bending or rolling: 14 in the esophagus and five in the pharynx. After breakfast, 14 of the 19 malpositioned catheters were properly positioned whereas five remained bent or rolled. Those bent in the esophagus were more prone to unbending (12 of 14) than those bent or rolled in the pharynx (two of five). CONCLUSIONS: After LES location by manometry and demonstration of acid pH during the pH step-up technique, the pH electrode was properly placed in more than 95% of cases. Nevertheless, it cannot be completely guaranteed that the pH catheter will not bend or roll, and the pH electrode will not be malpositioned. Eating immediately after electrode placement resolves this problem in the majority (75%) of cases. Therefore, we recommend that patients undergoing esophageal pH-metric studies be instructed to eat as soon as possible after electrode placement to minimize these possible pitfalls.     

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.     

Gastroesophageal pH step-up inaccurately locates proximal border of lower esophageal sphincter

Limiting the widespread use of 24-hr pH monitoring is the necessity of manometrically placing the pH probe 5 cm above the proximal lower esophageal sphincter (LES) border. Therefore, we prospectively compared LES localization by gastroesophageal pH step-up with manometry in 71 patients and 14 asymptomatic volunteers. The gastroesophageal pH step-up significantly correlated with the proximal LES border in patients (r=0.53, P<0.0001) and volunteers (r=0.91, P<0.0001). Based on previously published criteria, the pH step-up value was considered acceptably accurate if it was within ±3 cm (6 cm total span) of the manometrically determined proximal LES border. In 58% of patients and 29% of volunteers the pH step-up occurred outside this accuracy range. Esophagitis (P=0.015) and abnormal reflux parameters (P=0.002) were variables contributing to this error. Subsequent analysis found that the pH step-up overestimated the proximal LES border and occurred at the midportion of the sphincter. The pH step-up still inaccurately located the mid LES in 34% of patients. Therefore, manometry should remain the standard for accurate LES localization prior to placing the pH probe.     

Safety and tolerability of transoral Bravo capsule placement after transnasal manometry using a validated conversion factor

OBJECTIVES: To prospectively calculate and validate a conversion factor in healthy volunteers that allows accurate nonsedated, transoral (TO) Bravo capsule placement after transnasal (TN) manometry, and to evaluate the ease and safety of nonendoscopic Bravo placement compared with endoscopic placement. METHODS: Part 1. Twenty-five healthy volunteers underwent sequential TN and TO esophageal manometry to measure the distance to the lower esophageal sphincter (LES). A TN to TO conversion factor was calculated from these measurements. Part 2. Twenty volunteers underwent TN manometry followed by unsedated TO Bravo capsule placement using the conversion factor calculated in part 1. TN endoscopy then measured the location of the Bravo capsule in relationship to the squamocolumnar junction (SCJ). Part 3. During an 18-month period, 370 consecutive patients referred for a Bravo procedure underwent nonendoscopic, unsedated TO placement (308 patients) or standard endoscopically assisted placement (62 patients). RESULTS: Part 1. All 25 volunteers completed TN and TO manometry; a conversion factor of 4 cm was calculated. Part 2. Using the calculated conversion factor of 4 cm, a Bravo capsule was deployed TO 5 cm above the proximal border of the LES. The mean +/- standard deviation (SD) TN endoscopic distance to the capsule was 6.0 cm (+/-0.3 cm) above the SCJ. Part 3. A total of 333 patients completed the entire study (90%). Analysis of 48-h pH measurements did not reveal any significant differences between the two groups. CONCLUSIONS: A reliable and valid conversion factor of 4 cm following TN manometry permits accurate TO placement of the Bravo capsule without endoscopy. TO, unsedated Bravo placement is safe, well tolerated, and may minimize costs and potential risks associated with endoscopy.     

酸袋在反流性食管炎中作用的研究

目的 探讨酸袋在反流性食管炎中的作用.方法 应用胃食管反流病问卷(RDQ量表)和胃镜检查确诊15名健康者和24例反流性食管炎患者.使用4通道食管测压系统确定受试者下食管括约肌(LES)位置,将单通道pH电极置于LES远端下方1 cm处监测空腹pH值o.5 h,给予标准餐后继续监测pH值2 h,然后将探针移至LES近端上方5 cm处行24 h动态pH临测.结果 16例反流性食管炎患者(66.67%)与10名健康者(10/15)存在酸袋.反流性食管炎组较健康组酸袋出现时间早[11.00(4.25～17.00)min比30.00(15.50～54.25)min,P＜0.05]、平均pH值低[1.84(1.59～2.19)比2.32(1.96～2.71),P＜0.05].而餐前胃食管连接部平均pH值及酸袋持续时间差异无统计学意义.结论 反流性食管炎患者有异常食管酸反流,且酸袋出现时间早、平均pH值低,其食管黏膜损伤可能与此有关.     

Comparison of the Bravo wireless and Digitrapper catheter-based pH monitoring systems for measuring esophageal acid exposure

INTRODUCTION: We compared esophageal acid exposure data obtained during simultaneous esophageal pH studies using the Bravo wireless and the Slimline catheter-Mark III Digitrapper pH systems. METHODS: Twenty-five asymptomatic subjects underwent endoscopy with endoclip placement at the squamocolumnar junction (SCJ) and manometry to localize the lower esophageal sphincter (LES). A Bravo capsule was placed 6 cm above the SCJ and a Slimline catheter 5 cm above the LES. Relative positions were checked fluoroscopically. Synchronized pH data were compared by manual extraction into Excel spreadsheets. An in vivo pH reference was established with swallows of orange juice (pH 3.88). RESULTS: Median acid exposure time was greater with the Slimline compared to the Bravo system (Slimline, 3.4%; Bravo, 1.76%, p < 0.05) but electrode positions were similar. The dominant source of discrepancy between systems was an offset in recorded pH values around pH 4 as evidenced by the recorded values of the swallowed orange juice. Bench-top testing suggested that this offset was mainly attributable to the software designed to compensate for the difference in electrode recording characteristics between room and body temperature. After adjusting the pH data sets to accurately reflect actual orange juice pH, acid exposure between systems was similar (Slimline, 0.90%; Bravo, 1.15%). CONCLUSION: The Slimline system on average over-recorded esophageal acid exposure compared to the Bravo system largely because of a flawed software scheme for electrode thermal calibration. Accuracy of pH data sets from both systems can be improved by scrutiny for artifacts and use of an in vivo pH reference.     

Correlation of esophageal pH and motor abnormalities with endoscopic severity of reflux esophagitis

Motility abnormalities, common in gastroesophageal reflux disease, are likely to be related to endoscopic esophagitis. We studied pH and manometry parameters in relation to the severity of esophagitis. Forty-seven patients with symptomatic gastroesophageal reflux disease for > 3 months were evaluated by: (i) endoscopy (grading of esophagitis by Savary-Miller classification); (ii) mucosal biopsy; (iii) manometry; and (iv) 24-h pH-metry. We found Savary-Miller's grades of: 0 (9 patients out of 47), I (16/47), II (16/47), III (4/47), IV (2/47). Distal esophageal contraction amplitude was lower in severe (grade II to IV) as compared with mild (grade 0 and I) esophagitis (49 [7-182] versus 83 [27-196] mmHg [P = 0.001]). The length and pressure in the lower esophageal sphincter (LES), duration and velocity of contraction in the body, number of episodes of reflux and long-duration reflux, longest reflux, median pH, per cent of time with pH < 4 and DeMeester scores were not significantly different between the two groups. The area under pH 4 showed a negative correlation with LES pressure and amplitude of distal esophageal contractions. We conclude that higher endoscopic grades of esophagitis are associated with lower amplitude of contraction in distal esophagus. Lower LES pressure and distal esophageal contraction amplitude are associated with greater area under curve for pH below 4.     

正常人和胃食管反流病人的昼夜食管pH和动力变化

目的:为探讨正常人和胃食管反流病(gastroesophageal reflux disease,GERD)病人昼夜食管运动规律以及食管运动与酸反流的关系。方法:45例GERD病人和10名正常人均接受食管测压和动态食管pH及压力同步监测。结果:(1)下食管括约肌压、远端食管蠕动压及有效食管蠕动百分比在酸反流DeMeester高计分组明显低于低计分组(P<0.05),在反流性食管炎组也明显低于非反流性食管炎组(P<0.05)。(2)有GERD症状或食管炎的卧位有效蠕动百分比明显低于立位(P<0.05)。反流性食管炎组80％有夜间或伴有夜间反流,而不伴反流性食管炎的GERD无1例出现夜间反流。结论:昼夜食管pH和压力动态监测有利于进一步探讨GERD的运动病理,除LES功能外,食管清除功能在GERD发病中起重要作用。     

Effects of transjugular intrahepatic portosystemic shunt (TIPS) on esophageal motor function and gastroesophageal reflux

The effects of transjugular intrahepatic portosystemic shunt (TIPS) placement on esophageal motor function and gastroesophageal reflux were investigated in patients with esophageal varices. In six men with esophageal varices, esophageal manometry and upper gastrointestinal endoscopy were performed before and 15–20 days after TIPS placement. Intraesophageal pH monitoring was performed in the four patients with severe esophageal varices (defined as the largest sized varices) following TIPS placement. Findings were compared with those in six healthy men (controls) who underwent esophageal manometry and intraesophageal pH monitoring. The esophageal varices resolved or were reduced after TIPS placement. Resting lower esophageal sphincter (LES) pressures were similar in the study group before and after TIPS placement and in the control subjects. The incidence and progression of esophageal contractions were similar in the study group before and after TIPS placement and in the control subjects. At 3 cm above the LES, the amplitude of esophageal contraction after TIPS placement was significantly higher than that before TIPS placement. At 3 and 8 cm above the LES, the amplitude of esophageal contraction in the control subjects was significantly higher than that in the study group before and after TIPS placement. Esophageal acid exposure time after TIPS placement was similar to that in the controls. TIPS placement is a useful treatment that improves esophageal motor function without the occurrence of pathologic gastroesophageal reflux. (Received May 28, 1997; accepted Sept. 26, 1997)     

Gastroesophageal reflux before and after Helicobacter pylori eradication. A prospective study using ambulatory 24-h esophageal pH monitoring

The aim of this study was to assess prevalence of GERD before and after Helicobacter pylori (HP) eradication utilizing 24-h esophageal pH/manometry studies. Helicobacter pylori status was confirmed by the Campylobacter like organism test. Those testing positive underwent 24-h pH/manometry followed by HP eradication therapy and urea breath test. Patients were followed up at 6 months and then at 1 year when they underwent a repeat 24-h pH/manometry. Twenty patients, 10 with non-ulcer dyspepsia (NUD) and 10 with duodenal ulcer (DU) were enrolled, though only 10 patients attended for a repeat 24-h pH/manometry study. The patients were well matched, though patients with NUD had a significantly higher symptom score at entry compared with the DU group (8.5 vs 5.7, P < 0.05). The pH and esophageal manometry data were similar in the two groups. Overall nine patients (45%; DU = 5, NUD = 4) had evidence of GERD prior to HP eradication and it persisted one year after cure of the infection. The reflux disease occurred in the presence of normal LES pressure (mean 15.6 +/- 3.3 mmHg). New onset GERD was uncommon after cure of HP infection, occurring in only one patient with NUD. Overall HP eradication had no impact on percentage of time pH < 4 (4.69 +/- 3 vs 4.79 +/- 3), episodes > 5 min (9.8 +/- 16 vs 15.5 +/- 25.3) and Johnson DeMeester Score (16.8 +/- 7.5 vs 26.8 +/- 18). In addition successful cure of HP produced no significant changes in LES pressure (17.9 +/- 3.8 mmHg vs 19.3 +/- 4.6 mmHg), and other esophageal manometry data. Half of HP-positive patients with NUD and DU have evidence of GERD before HP eradication. This persists after successful cure of the infection. New onset GERD occurs very uncommonly one year after HP eradication.     

胃食管反流病食管测压与24小时pH监测的相关性研究

目的：对５２例有胃食管反流症状的患者进行食管测压及２４小时ｐＨ监测，运用统计学方法分析测压和ｐＨ结果，研究其相关性。方法：应用多导胃肠功能测定仪及便携式ｐＨ监测记录仪，对５２例有胃食管反流症状的患者进行食管测压及２４小时ｐＨ监测。结果：应用多元回归分析发现，ｐＨ的百分比和腹段下食管括约肌（ＬＥＳ）的长度、ＬＥＳ静息压及远端食管的蠕动压明显相关。依据测压及ｐＨ结果，使用ｔ检验方法，结果提示食管蠕动压不仅与ｐＨ＜４的百分化相关，也与酸反流大于５分钟的时间、最长反流时间有关（Ｐ＜００１）。结论：腹段ＬＥＳ的长度及食管下段的蠕动收缩是重要的抗反流屏障。食管酸暴露时间延长减弱食管体部酸清除能力     

Relationship of Intraluminal pH and Pressure within the Lower Esophageal Sphincter

To determine the relationship between lower esophageal sphincter (LES) intraluminal pressure and its intraluminal pH, we studied six healthy volunteers. We recorded intraluminal pressure and pH concurrently using rapid pull-through, slow pull-through, and station pull-through, as well as, rapid push-through and slow push-through techniques. The results showed that LES length was 35 +/- 4 (SE) mm by RPT and 30 +/- 3 mm by SPT. The pressure was maximal in the proximal half of the LES. On rapid pull-throughs, the intraluminal pH rose from about 1.5 to reach a value of about 2.5 at the peak of the high pressure zone. With continued withdrawal into the esophageal body, the recorded pH rose minimally to about 3-4. On push-throughs, the pH recorded along the LES was the same as that of the esophageal body. After the electrode cleared the LES, the pH abruptly fell to gastric pH. During station pull-through with the electrode 0.5-1.5 cm proximal to the distal LES margin, transient pH drops were observed with swallows. With rapid swallows, however, the pH drop did not occur until after the last swallow. This finding suggests that the pH drops with swallows were due to axial LES movement rather than gastroesophageal acid reflux. We conclude that 1) the relationship of the gastroesophageal pH transition zone and LES high pressure zone is better defined by a sphincter push-through than a pull-through; 2) the transition between gastric and esophageal pH occurs either at or slightly distal to the distal LES margin; and 3) swallow-induced axial LES movement may cause spurious recording of acid reflux when the pH probe is positioned within the distal half of the LES.     

Proximal Sensor Data from Routine Dual-Sensor Esophageal pH Monitoring Is Often Inaccurate

Dual-sensor esophageal pH monitoring is routinely used to diagnose GERD. However, the proximal sensor may not be in proximal esophagus in patients with shortened esophagi. Our objective was to determine how often the proximal sensor was misplaced and to determine the effect on pH monitoring. Superior margins of the upper and lower esophageal sphincters (UES and LES) were determined prospectively in consecutive patients. Dual sensors were placed 20 and 5 cm above the LES with a fixed 15-cm spacing pH catheter. Patients were classified into subgroups based on the actual location of the proximal sensor. In 661 patients, the proximal pH sensor was in the hypopharynx in 9% of patients, within the UES in 36%, and in the proximal esophagus in 55%. Spearman's correlation for acid exposure was very good between the dual sensors when the proximal sensor was in the proximal esophagus (R = 0.76) but was poor when the proximal sensor was misplaced in the hypopharynx (R = 0.28). The proximal sensor was misplaced in 45% of patients undergoing dual-sensor esophageal pH monitoring. It is important to locate the UES by manometry before interpreting the proximal esophageal pH data.     

Transient Lower Esophageal Sphincter Relaxations (TLESRs) Are the Major Mechanism of Gastroesophageal Reflux but Are Not the Cause of Reflux Disease

In healthy subjects, the rate of acid reflux during transient lower esophageal sphincter relaxations (TLESRs) is more frequent at the proximal margin of the LES. In this study, we investigated the hypothesis that the rate of acid reflux at the proximal margin of LES during TLESRs is similar in reflux disease to that in healthy subjects. Concurrent esophageal manometry and pH monitoring were performed in the sitting position for 3 hr after a standard meal in 10 patients with reflux disease and 10 age-matched healthy controls. The rate of TLESRs in patients with reflux disease (5.0/hr [3.3–6.7]; median [interquartile range]) was similar to that of controls (4.5/hr [3.7–5.7]). The incidence of acid reflux 7 cm above the LES during TLESRs in patients (48.1% [27.2–71.4%]) was significantly higher than that in controls (10.9% [0.0–18.8%]) but there was no difference 2 cm above the LES (75.0 [69.2–87.5] vs. 74.3 [55.5–90.0%]). The rate of TLESRs and the incidence of acid reflux during TLESRs are not increased in reflux disease. These findings, therefore, indicate that reflux disease is not a disorder of TLESRs and relates more to the proximal extent of the refluxate.     

Noncardiac chest pain of esophageal origin

Opinion Statement Cardiac and musculoskeletal disease should be excluded before considering an esophageal etiology for chest pain. Acid reflux is a common cause of chest pain and should be identified and treated. A therapeutic trial should consist of a proton pump inhibitor (omeprazole 20 mg or lanzoprazole 30 mg) given one or two times per day for at least 6 to 8 weeks. An alternative is to use an ambulatory pH study to confirm reflux. Also, if the patient fails the initial treatment, reflux should be confirmed with pH testing before increasing the dose of proton pump inhibitor or considering combination or surgical therapy. Esophageal manometry should be considered in patients with chest pain and dysphagia. It is also reasonable to perform manometry before a pH study since manometric localization of the lower esophageal sphincter (LES) is needed to ensure accurate pH probe placement. Only after manometric confirmation of a spastic esophageal motility disorder should patients be treated for esophageal spasm. In these patients, it is reasonable to try a long-acting formulation of a calcium-channel blocker or nitrate. Patients with chest pain who have a negative cardiac evaluation and who do not have reflux may have an abnormality in esophageal or cardiac sensation. These patients should be treated with a trial of an antidepressant and considered for referral to a mental health practitioner. All medication trials should continue at least 6 to 8 weeks to avoid a placebo effect and to allow adequate time for a therapeutic response.     

Significantly Reduced Acid Detection at 10 Centimeters Compared to 5 Centimeters above Lower Esophageal Sphincter in Patients with Acid Reflux

Ambulatory pH monitoring of the esophagus is carried out by positioning a pH sensor 5 cm above the lower esophageal sphincter (LES). There are several techniques to locate the LES, and each method has a different margin of error. This work used dual pH sensors to monitor simultaneously at two different levels (5 and 10 cm above the LES) in order to establish the possible magnitude of error that could arise from inaccurate placement of a pH probe. Thirty-four patients with symptoms of gastroesophageal reflux (GER) were studied. They were grouped as 20 patients with pathological reflux (GER group) and 14 patients with physiological reflux, based on a reflux score derived by Johnson and DeMeester for distal esophageal pH monitoring. When the reflux scores were compared, the difference between the two monitoring levels was statistically significant in the GER group ( p < 0.001) but not in the physiological reflux group ( p = 0.09). In the GER group, the difference in the Johnson and DeMeester score accounted for a change in clinical diagnosis in nine of the 20 patients if the pH probe was placed at 10 cm above the upper margin of LES. Proximal reflux episodes (10 cm above LES) were preceded by distal reflux episodes (5 cm above LES) in 97% (878/901) of cases. Accurate probe placement is essential in the diagnosis of GER.     

Effects of a pH electrode across the lower esophageal sphincter

Recent studies have suggested that combined monitoring of the esophagus and stomach for prolonged periods may be the best method for investigating patients with upper gastrointestinal complaints. However, the effects of an electrode across the LES on esophageal reflux parameters have not been extensively studied. We studied 10 healthy volunteers and 10 patients with GERD twice with 24-hr pH monitoring. In phase 1, two glass electrodes were placed 1 cm below the UES and 5 cm above the LES. One week later in phase 2, patients were restudied with one electrode 5 cm above and one 5 cm below the LES. Although total acid exposure remained the same in healthy volunteers, three volunteers who spontaneously refluxed at night had abnormal prolongation of their supine acid exposure during phase 2 of the study. In patients with GERD, the electrode across the LES resulted in significant (P=0.01) increase in supine acid exposure and showed a strong tendency for the number of reflux episodes >5 min supine (P=0.02) and longest reflux episode supine (P=0.06) to increase without a change in the number of reflux episodes. In conclusion, a small glass electrode across the LES results in prolongation of supine acid exposure in both healthy volunteers spontaneously refluxing at night and the majority of patients with GERD. This results from the electrode interfering with clearance of refluxed acid in the supine position. Thus, combined esophageal and gastric pH monitoring may have important limitations in investigating gastroesophageal symptoms.     

Ambulatory esophageal pH testing

Over a 30-month period, 867 esophageal pH studies were conducted in a Canadian teaching hospital; of these, 315 tests were recorded in patients who were first-time referrals having no chest or upper gastrointestinal surgery and taking no medication that would affect the results. Patients were referred by gastroenterologists, general surgeons, ENT surgeons, thoracic surgeons, and a miscellaneous group. Patients were classified based on: pH results [abnormal=% total time pH<4.0 (ie, >6.0%)], manometry (abnormal=LES resting pressure<5 mm Hg and/or abnormal peristalsis), and gender. Fifty-one percent (162/315) of the patient records demonstrated abnormal reflux. Intergroup comparisons of severity of reflux using two-way analysis of variance demonstrated no significant differences (P=0.13). In the 162 patients who refluxed, 70% (N=108) had normal motility studies; however, when the severity of reflux was compared, patients with abnormal motility (N=54) demonstrated significantly more severe reflux (19.8±12.8 vs 16.2±11.3)P=0.02. In those patients with abnormal manometry, no significant differences (P=0.44) in the severity of reflux were found among those with abnormal peristalsis (N=27), low resting pressure (N=17), or a combination of aperistalsis and low LES pressure (N=10). Symptomatic patients with reflux (N=107) demonstrated a significantly greater percent time pH<4.0 than those with asymptomatic reflux (N=55); 18.1±11.5% vs 16.2±12.7%,P=0.04. When the severity of reflux by gender was compared, no significant differences were found [18.3±11.9 (male)N=91 vs 16.2±11.9 (female)N=71,P=0.11]. The results from this study show that: (1) esophageal pH testing is important in subspecialties other than gastroenterology and that the clinical yield is high in all referring groups, (2) esophageal pH testing and manometry are complimentary tests, but that reflux occurs commonly in association with normal manometry, (3) asymptomatic reflux was found in 34% of the patients with abnormal reflux scores, and (4) the severity of reflux in male and female patients is similar.     

Effect of baclofen on the acid pocket at the gastroesophageal junction

Previous studies established that a pocket of highly acidic gastric juice is present postprandially at the gastroesophageal junction in man. The GABA‐B agonist baclofen inhibits postprandial reflux events through its effects on the lower esophageal sphincter (LES). The aim of the current study was to investigate whether baclofen would affect the location and the extent of the postprandial acid pocket in healthy volunteers. Twelve healthy volunteers underwent acid pocket studies on two different occasions, at least 1 week apart. LES position was determined preprandially with pull‐through manometry. Dual pH electrode and manometry probe stepwise pull‐through (1 cm/minute, LES–10 to +5 cm) was performed at 30‐minute intervals for 150 minutes, with administration of placebo or baclofen 40 mg after the first and ingestion of a liquid meal after the second pull‐through. After placebo, a significant drop in intragastric gastric pH was present at the gastroesophageal junction after the meal, reflecting the acid pocket, and this was associated with a drop in LES pressure. Baclofen did not affect the presence of the acid pocket, but prevented the postprandial drop in LES pressure, and the extent of the acid pocket above the upper margin of the manometrically located LES was significantly decreased by baclofen (1.6 ± 0.7 vs. 0.3 ± 0.4 cm at 60 minutes, 2.2 ± 0.6 vs. 0.2 ± 0.6 at 90 minutes, and 1.5 ± 0.5 vs. 0.7 ± 0.7 cm at 120 minutes, all P < 0.05). Baclofen does not alter the intragastric acid pocket, but limits its extension into the distal esophagus, probably through an increase in postprandial LES pressure.