Combined esophageal and gastric pH-metry in healthy volunteers. Influence of cable through LES and effect of misoprostol

Wireless pH recording immediately above the squamocolumnar junction improves the diagnostic performance of esophageal pH studies

BACKGROUND AND AIMS

The optimal position for pH electrode placement in the diagnosis of gastroesophageal reflux disease (GERD) is unknown. The aim of this study was to evaluate the discriminatory power of targeted pH recording immediately above the squamocolumnar junction (SCJ) and to compare the results with those obtained by simultaneous recording at the conventional level for pH monitoring.

SUBJECTS AND METHODS

Sixty-two patients with typical reflux symptoms and 49 asymptomatic volunteers underwent 48-h simultaneous wireless pH monitoring with two endoscopically placed pH recording capsules, one immediately above the SCJ and one at the traditional position, 6 cm above the SCJ. The diagnostic accuracy, sensitivity, and specificity of pH monitoring at the two levels were analyzed using receiver operating characteristics (ROC) curves.

RESULTS

Of the 62 patients (39 men and 23 women, median age 48 yrs), 32 patients had erosive esophagitis and 30 had no endoscopic evidence of mucosal injury. Analysis of the area under the ROC curve (AUC) indicated that the total percent time with pH<4 for the entire 48-h period was the parameter that best distinguished GERD patients from controls. pH monitoring performed directly above the SCJ significantly increased the number of patients correctly classified with GERD compared to standard electrode placement. With a predefined test specificity of 90%, pH monitoring immediately above the SCJ increased the sensitivity of the test from 63% to 86% in all patients, from 78% to 97% in patients with esophagitis and from 47% to 73% in patients with no esophagitis.

CONCLUSIONS

Compared to standard electrode placement, wireless pH recording immediately above the SCJ improved the diagnostic performance of esophageal pH monitoring in patients with GERD.

Acid reflux immediately above the squamocolumnar junction and in the distal esophagus: simultaneous pH monitoring using the wireless capsule pH system

OBJECTIVES

The pattern of reflux in the most distal esophagus of asymptomatic individuals is largely unknown. Using a wireless technique we compared the degree and the pattern of acid reflux just above the squamocolumnar junction (SCJ) with that measured at the conventional level for pH monitoring.

METHODS

Fifty-three asymptomatic volunteers underwent endoscopy with transoral placement of two pH recording capsules, one immediately above and one 6 cm above the SCJ. Ambulatory pH monitoring was performed during 48 h.

RESULTS

Three subjects were excluded as the distal capsule was inadvertently placed with the pH electrode below the SCJ. The median percent time with pH < 4 and the median number of reflux episodes were significantly higher immediately above the SCJ compared with that found more proximally (1.6%vs 0.9% and 67 vs 26, p < 0.0001). Of all acid reflux events, 69% were isolated episodes immediately above the SCJ. Only 26% of reflux episodes detected at the SCJ extended to the more proximal pH electrode. Reflux events occurring just above the SCJ were more acidic. The number of reflux events with a minimum pH below 2 or 3 was significantly higher at the SCJ compared with that recorded by the upper capsule (16% and 44%vs 6% and 34%, p < 0.0001).

CONCLUSIONS

Conventional pH monitoring substantially underestimates the degree of acid exposure in the most distal esophagus. In healthy subjects, acid exposure immediately above the SCJ was considerably higher and was characterized by shorter reflux episodes that had a lower minimum pH compared with that measured at the traditional level for pH monitoring.

Wireless oesophageal pH monitoring: feasibility, safety and normal values in healthy subjects

OBJECTIVE

A new wireless technique for oesophageal pH monitoring has recently been introduced (Bravo). To implement this technique in clinical practice, values of normal oesophageal acid exposure need to be defined in a large age- and gender-matched healthy population. The aims of this study were to investigate the feasibility and safety of the wireless technique and to establish normal values for oesophageal acid exposure.

MATERIALS AND METHODS

Fifty-seven asymptomatic subjects underwent upper gastrointestinal endoscopy with transoral placement of a radio-transmitting capsule 6 cm above the squamocolumnar junction. Oesophageal acid exposure was monitored via a portable receiver during 48 h.

RESULTS

Seven men were excluded from the study: capsule dysfunction in 1 and oesophagitis in 6. Fifty subjects (25 M, 25 F, median age 42 years) were included in the study. The radio-transmitting capsule was successfully attached to the oesophageal mucosa in all cases and there were no complications. During pH monitoring 2 capsules were prematurely detached after 32 and 36 h, respectively. The median percentage time with oesophageal pH of less than 4 was 0.7% on day 1 and 1.0% on day 2 (p = 0.033) and the 95th percentile for the 48-h recordings was 4.4%.

CONCLUSIONS

Ambulatory pH monitoring using the Bravo system is feasible and appears to be safe. This is the first study to establish normal values for oesophageal acid exposure in a large age- and gender-matched healthy population and offers a basis for the use of the wireless technique in clinical practice.

Does the supplementation of the formula with fibre increase the risk of gastro-oesophageal reflux during enteral nutrition? A human study

BACKGROUND & AIMS

Fibre-supplements in enteral feeding could increase the risk of gastro-oesophageal reflux (GOR). The aim of this study was to assess in humans the physiological effects of the supplementation of the enteral diet with different types of dietary fibre on gastro-oesophageal reflux episodes, gastric acidity and gastric emptying.

METHODS

pH profiles were compared in 12 healthy volunteers between three different formula (500 kcal, 250 mL x h-1) delivered in a random order and containing either no fibre, either soy polysaccharide fibre only or mixed fibre from pea and inuline. Enteral diets were instilled through a nasogastric tube. Oesophageal and gastric pH recordings were combined with the ultrasound measurement of gastric antral area during the infusion.

RESULTS

More GOR were observed with a fibre-free diet (median 4, range 1-10) than with a mixed (median 1.5, range 0-5) (P=0.04) or soy polysaccharide fibre (median 1.5, range 0-5) (P=0.04) diet. The median duration of GOR was longer with the mixed fibre (median 3.6, range 1.8-7.2) than with the fibre-free diet (mean 1.8 min, range 1-3.6) (P<0.05). The number of GOR episodes lasting more than 5 min, the duration of the longest GOR and the percent of time under pH 4 were not significantly different with the three diets. The intragastric pH profile and the ultrasound antral area were not different with all three diets.

CONCLUSIONS

Addition of fibre to the enteral formula had limited effects on the onset of GOR episodes. It decreased the number of GOR but increased their duration. These effect were more pronounced with the formula containing soluble fibre. At variance, the addition of fibre had no significant effect on gastric emptying and gastric acid secretion.

Does the size of nasogastric tubes affect gastroesophageal reflux in children?

BACKGROUND

To evaluate the effects of nasogastric tube insertion and different nasogastric tube sizes on gastroesophageal reflux in children.

METHODS

During a prospective randomized study, 29 patients aged 1 month to 4 years (median, 9 months) underwent 24 hours of continuous esophageal pH monitoring to rule out gastroesophageal reflux as the cause of severe pulmonary problems. Each patient was monitored without nasogastric tube for 16 hours (baseline), and thereafter the first nasogastric tube, small (8-Fr) or large (10-Fr or 12-Fr), was placed. Four hours later, the original nasogastric tube was replaced by a new one of large (instead of small) size or of small (instead of large) size. We selected the times of wakefulness in these study periods and compared the number of reflux episodes (NREs), the number of reflux episodes that lasted more than 5 minutes (NRE>5), and the percentage of time with esophageal pH less than 4 (PTP<4).

RESULTS

The 12-Fr group in comparison with the 8-Fr group and baseline showed significant difference (P<0.05) in the NRE>5 and PTP<4 parameters. No significant differences were found when comparing 8-Fr versus 10-Fr groups and baseline. In children with (n = 20) and without (n = 9) gastroesophageal reflux, comparison of the various reflux parameters between baseline and the different sizes of nasogastric tubes showed the same results.

CONCLUSIONS

Size of the nasogastric tubes is a significant factor in predisposing the child to gastroesophageal reflux. Large nasogastric tubes interfere with the clearance of the refluxed acid from the esophagus.

Endoscopic grading of reflux oesophagitis: what observations correlate with gastro-oesophageal reflux?

BACKGROUND

The recognition of minor endoscopic changes is important in correctly diagnosing patients with reflux oesophagitis, but the significance of minor lesions and what observations to use in endoscopic classification are disputed. Our aim was to relate endoscopic observations in reflux oesophagitis with the severity of gastro-oesophageal reflux.

METHODS

On endoscopy of 64 consecutive untreated patients with uncomplicated reflux oesophagitis, accurate records were made prospectively of the following variables: axial extent of endoscopic changes, width of the lesions, presence of whitish exudate in the lesions, and presence and length of a hiatal hernia. Multiple linear regression analysis examined which of these factors were significantly related, at the 5% level, with gastro-oesophageal reflux as measured at intraoesophageal 24-h pH-metry.

RESULTS

Presence of whitish exudate and width of lesions were significantly associated with severity of gastro-oesophageal reflux. Median fraction of the recording period with pH <4 was 5.9% in patients with narrow red lesions, 12.5% in patients with narrow, whitish lesions, and 20.3% in patients with broad lesions (P < 0.0001). The mean duration of reflux episodes was significantly longer and the number of nocturnal episodes lasting more than 5 min was significantly higher in patients with broad lesions.

CONCLUSION

Red spots and streaks, even without whitish exudate, are significantly related to pathologic gastro-oesophageal reflux. Whitish exudate is related to more severe reflux, and broad lesions to a longer mean duration of the episodes. The presence of whitish exudate in lesions and the width of the lesions are important observations to use in the classification of reflux oesophagitis.

Effect of general anaesthesia on prolonged intraoesophageal pH monitoring

Investigation of gastro-oesophageal reflux often includes endoscopy, usually under general anaesthesia, and pH monitoring. In most cases, the pH probe is passed when the child is awake and is poorly tolerated. The effect of general anaesthesia on pH monitoring is unknown. The aim of the study was to determine if placing the probe in the anaesthetised child gives a representative pH study. Twenty children aged 4 months to 13 years underwent oesophago-gastroduodenoscopy under general anaesthesia. A pH electrode was placed under direct vision in the distal oesophagus. pH monitoring was begun after completion of anaesthesia and continued for 18-24 hours. The study was repeated within 14 days without anaesthetic. The reproducibility of values of percent pH < 4, number of reflux episodes/hour, reflux episodes lasting > 5 min, and longest reflux episode was 85%, 90%, 75%, and 75% respectively. These results are comparable with those in adults and children in whom pH studies were performed on consecutive days (without anaesthetic) keeping all variables constant. Therefore pH data collected in a child within 24 hours of endoscopy under general anaesthesia are representative.

Simultaneous gastroesophageal pH monitoring and the diagnosis of alkaline reflux

The diagnosis of alkaline gastroesophageal reflux (AGER) by esophageal pH-monitoring is elusive because several other causes may raise esophageal pH above 7. This study approaches the issue by simultaneously recording esophageal and gastric pH with a 2.1 mm assembly of two antimony electrodes in refluxing (n = 69) and nonrefluxing (n = 40) children. On the basis of the information gathered, patients were divided into four groups: acid refluxers (GER, n = 40 or 57%), alkaline refluxers (AGER, n = 8 or 11%), alkalacid refluxers (AAGER, n = 15 or 22%), and silent refluxers or false negatives (SGER, n = 6 or 9%). Children with AGER could not be differentiated from other refluxers nor from controls by esophageal pH information alone. Prolonged gastric buffering or alkalinization could be documented in both AGER and AAGER children, indicating extended duodenogastric reflux (DGR) in them. The incidence of esophagitis was not significantly different between the groups of refluxers: 75% for AGER and AAGER, 73% for GER, and 67% for SGER. AGER, a disorder involving both pyloric and gastroesophageal barriers, is as significant a problem in children as in adults and may lead to severe complications even in the absence of excessive acid exposure. Monitoring esophageal pH alone is insufficient for making the diagnosis of AGER. The diagnosis can be made with little more expense and similar patient discomfort using the two-probe test. We suggest the need for a critical reassessment of the current antacid and prokinetic GER treatments and of antireflux operations which leave DGR intact while correcting GER.

Gastric acidity and gastroesophageal reflux patterns in patients with esophagitis

Esophageal pH-metry is the test of choice for diagnosing gastroesophageal reflux. However, although it allows acid refluxes to be distinguished, it is of limited value for identifying alkaline or mixed (acid mixed with alkaline material) refluxes. To evaluate the ability of dual pH-metry to identify alkaline or mixed refluxes, the gastric acidity and gastroesophageal reflux pattern were evaluated simultaneously in 64 patients with mild-moderate esophagitis, in 28 patients with severe or complicated esophagitis, and in 20 healthy subjects. A dual esophageal gastric pH-probe allowed three different types of esophageal reflux to be distinguished: (a) acid refluxes, defined as a drop in esophageal pH to values less than 4 together with a gastric pH less than 4; (b) mixed refluxes, defined as a drop in esophageal pH from baseline to values greater than 4 associated with rises in gastric pH to greater than 4 values; (c) alkaline refluxes, defined as a rise in esophageal pH to greater than 7 associated with a simultaneous increase in gastric pH to greater than 4. Gastric acidity was more significantly reduced in patients with severe or complicated esophagitis than it was in healthy subjects (P less than 0.01). The reflux pattern in both mild-moderate and severe esophagitis was characterized by mainly acid refluxes and a marked increase in the time the esophagus mucosa was exposed to acid (P less than 0.001). Pure alkaline refluxes were rare (less than 1%) in both healthy subjects and esophagitis patients. The number of mixed refluxes was considerably higher in severe esophagitis patients than it was in either mild-moderate esophagitis patients or controls (P less than 0.05). The finding of mixed refluxes in severe or complicated esophagitis suggests that biliary acids and/or pancreatic enzymes are involved in the pathogenesis of severe forms of esophagitis.

Oesophageal pH-metry: should meals be standardized?

To assess the effect of a late-evening, high-fat meal on nocturnal supine gastro-oesophageal reflux, eight healthy volunteers (aged 20 to 38 years) underwent two ambulatory oesophageal pH-metry recordings, the first after a standardized light meal at 1930 h and the second after a high-fat meal including peppermint and chocolate, at 2130 h. Between 2300 and 0700 h, when subjects were supine, the median acid exposure time (percentage recording with pH less than 4) increased from 0.0% (range, 0.0-6.8%) after the standardized meal to 7.9% (0.0-17.8%) after the high-fat meal (p = 0.031). Similarly, the median number of reflux episodes increased from 0 (0 to 11) after the standardized meal to 7 (0 to 26) after the high-fat meal (p = 0.031). Reflux occurred after both meals, but, in general, persistent nocturnal reflux was observed only after the high-fat meal. Thus, the analysis of oesophageal pH recordings should consider the effects of meal composition and timing on oesophageal acid exposure.

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 greater than 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.

Reproducibility of long-term ambulatory esophageal combined pH/manometry

Long-term ambulatory esophageal manometry is used increasingly, but normal values and data on the reproducibility of the method are not available. Thus, studies were conducted using paired 24-hour recordings, separated by 1-4 weeks, in 24 healthy volunteers (aged 19-50). Computerized analysis of each two-channel pressure recording (5 and 15 cm above lower esophageal sphincter) determined mean contraction amplitude, duration, area under the curve, contractility and propagation velocity, and the proportion of propagated contractions during day and night periods. A combined glass pH electrode (5 cm above lower esophageal sphincter) was used to register acid reflux. Visual analysis of the 24-hour contractility patterns showed marked intraindividual reproducibility but, although most subjects showed similar meal-associated increases and sleep-associated decreases in contraction frequency and amplitude, considerable interindividual variation was observed. This was confirmed by comparing the variation between subjects in the first and second recordings with the variation between recordings in the same subject; for all pH and manometry variables, the coefficient of variation was two to three times greater between subjects than between recordings in the same subject. The recordings were highly reproducible within subjects (nighttime contraction duration, P less than 0.05; all other variables, P less than 0.01). Thus, computerized ambulatory pH manometry is reproducible and because healthy volunteers have a characteristic individual pattern of esophageal motility, the method is perfectly suitable for repeated-measure design physiological and pharmacological studies. However, generally applicable normal values are difficult to define.

Intragastric and intraoesophageal pH monitoring in duodenal ulcerpatients: effect of the new histamine H2-receptor antagonist ramixotidine

The effect of the new histamine H2-receptor antagonist ramixotidine 750 mg p.o., administered at 22.00 h, on intragastric and intraoesophageal pH monitored from 22.00 h to 08.00 h, was studied in a double-blind cross-over trial in 11 duodenal ulcer patients. Placebo and ramixotidine were given to each patient on 2 consecutive days in a randomized sequence. Three patients were excluded from the intragastric pH analysis as the records on the second study day were technically inadequate. No significant carry-over or sequence effect was noted. Intragastric hydrogen ion activity was significantly lower (p = 0.01) after ramixotidine than after placebo: median (range) 24 (9-100) vs 97 (27-188) mmol/l. The percentage of time with intraoesophageal pH less than 4 was less than 5% in all but three recordings, with a maximum value of 12%, and it was not significantly different after the two treatments.