24-h Multichannel Intraluminal impedance-pH Research Articles

"Normal Values of 24H Multichannel Intraluminal Impedance pH-Metry in a Greek Obese Population Based on Montreal Definition of Gerd".

Although several studies reporting normal values of 24h multichannel intraluminal impedance pH (MIIpH) have been published, none of them has ever studied obese individuals. The purpose of this study is to determine overall frequency and duration of reflux episodes (acid and non-acid, supine-upright, post and preprandial) in obese asymptomatic volunteers. Obese volunteers were enlisted during their preoperative evaluation for bariatric surgery. Volunteers had no gastroesophageal reflux disease (GERD) symptoms and no evidence of esophageal mucosal injury on endoscopy. Participants underwent a 24h MIIpH. In this prospective observational study, data of 22 obese individuals were analyzed. Mean age was 41.9 years and mean BMI was 47.1 kg/m(2). Mean total reflux episodes was 55.6 and 95th percentile was 99.7. Mean percentage of total time with pH <4 was 2.59 % and 95th percentile was 8.57 %. Mean percentage of bolus exposure was 1.84 % with 95th percentile being 4.47 %. Postprandial acid reflux episodes were statistical significant more frequent in comparison to preprandial acid reflux episodes (19.41 vs. 15, p = 0.008). Mean acid clearance duration was 3.6 times higher than median bolus clearance duration (56.05 and 15.55 s, respectively, p = 0.868). Our study is the first to provide normal values of 24h MIIpH of asymptomatic obese. Normal values of 24h MIIpH of obese asymptomatic individuals differ from the reported normal values of non-obese healthy individuals; having more reflux episodes and equal or slightly higher median bolus exposure and acid clearance. Our results imply that new cut-off values should be employed in order to define GERD in obese individuals.

Pathophysiology of functional heartburn based on Rome III criteria in Japanese patients.

To investigate the pathophysiology of functional heartburn (FH) in Japanese patients. A total of 111 patients with proton pump inhibitor (PPI)-refractory non-erosive gastroesophageal reflux disease underwent intraesophageal pressure testing and 24-h multichannel intraluminal impedance-pH (24MII-pH) testing. The patients also completed several questionnaires while they were receiving the PPI treatment, including the questionnaire for the diagnosis of reflux disease (QUEST), the frequency scale for the symptoms of gastroesophageal reflux disease (FSSG), the gastrointestinal symptoms rating scale (GSRS), SF-36, and the Cornell Medical Index (CMI). The subjects were classified into FH and endoscopy-negative reflux disease (ENRD) groups based on the Rome III criteria. Thirty-three patients with esophageal motility disorder were excluded from this study, while 22 patients with abnormal esophageal acid exposure time (pH-POS) and 34 with hypersensitive esophagus (HE) were included in the ENRD group. The FH group included 22 patients with no reflux involvement. Sex, age, and body mass index did not differ significantly between the groups. The mean SF-36 values were < 50 (normal) for all scales in these groups, with no significant differences. The GSRS scores in these groups were not different and showed overlap with other gastrointestinal symptoms. The QUEST and the FSSG scores did not differ significantly between the groups. Neuroticism was diagnosed using the CMI questionnaire in 17 of the 78 included subjects within the pH-POS (n = 4), HE (n = 8), and FH (n = 5) groups, with no significant differences. Clinical characteristics of the FH and PPI-refractory ENRD groups were similar. Therefore, esophageal function should be examined via manometry and 24MII-pH testing to differentiate between them.

Correlation between hypersensitivity induced by esophageal acid infusion and the baseline impedance level in patients with suspected gastroesophageal reflux.

To evaluate the relevance between the pH parameters and baseline impedance level or esophageal hypomotility in patients with suspected gastroesophageal reflux. The recordings of 51 patients with heartburn, acid regurgitation, globus or noncardiac chest pain were analyzed. Evaluation included a 24-h multichannel intraluminal impedance-pH test while on off-proton pump inhibitor therapy over 1week, high-resolution manometry and Bernstein test. Mean baseline impedance level at the most distal portion of the impedance channel was assessed manually. Esophageal hypomotility was evaluated using transitional zone defect (TZD) and distal break (DB) length measurement. In the study subjects (n=51), 6 had a DeMeester score of more than 14.7 and 14 had a positive symptom index. The Bernstein test was positive in ten patients. The baseline impedance level was inversely correlated with the acid exposure time% (r=-0.660, P<0.001). Also, all reflux and weakly acid reflux time % measured by impedance monitoring showed a weak correlation with TZD+DB length (r=0.327 and 0.324, P=0.019 and 0.020, respectively). Although a positive Bernstein test has no relevance for the acid exposure time or acid-related symptoms as represented by the DeMeester score or symptom index, the baseline impedance level was significantly lower in patients with a positive Bernstein test than in those with a negative one (2,628.4±862.7 vs. 1,752.2±611.1Ω, P=0.004). A lower baseline impedance level is closely related to increased esophageal acid exposure. Hypersensitivity induced by esophageal acid infusion might be attributed to acid-induced mucosal changes of the esophagus.

Functional heartburn

Patients with heartburn and normal upper gastrointestinal endoscopy, normal oesophageal acid exposure, no symptom-reflux association and who fail to respond to a proton-pump inhibitor are classified as having functional heartburn (FH). This study aimed (i) to characterize the symptoms and functional abnormalities of patients with FH and (ii) to describe their clinical outcome. Among all patients referred for 24 h multichannel intraluminal impedance-pH (MII-pH), patients with FH were identified. The clinical characteristics and high-resolution oesophageal pressure topography recordings of FH patients were analyzed at the time of the 24-h MII-pH test. A symptom-related and health-related quality-of-life questionnaire was then sent to FH patients to assess the long-term outcome. Forty patients fulfilled the criteria for FH, representing 8.5% of the referred population. Twenty-two months after initial testing, 66% of patients still suffered from heartburn. The rate of mixed reflux (liquid/gas) was higher in patients with persisting heartburn at the final evaluation (63 vs. 50%, P=0.04). Sixty-six per cent of patients had one or more manometric abnormalities. Acid clearance time in MII-pH was significantly higher in patients with weak peristalsis than patients with normal peristalsis (60 ± 45 vs. 31 ± 19 s, P=0.03). A high rate of mixed reflux and/or a manometric abnormality were associated with a higher risk of persistent heartburn. FH is a chronic disorder with persisting symptoms in two-thirds of patients. An increased rate of mixed reflux and/or the presence of manometric abnormalities are associated with a higher risk of persisting symptoms and may help to identify the population with unmet therapeutic needs.

Impedance-pH monitoring and conventional pH monitoring are complementary methods to detect association between gastroesophageal reflux and apnea-related symptoms in preterm infants and neonates

Objective: To investigate the usefulness of Multichannel intraluminal impedance-pH (MII-pH) monitoring as compared with conventional pH monitoring for detecting Gastroesophageal reflux (GER) episodes and apnea-related symptom association in preterm infants and neonates. Methods: Twenty-three infants (16 preterm and 7 term infants) in hospital, who underwent 24-h MII-pH monitoring, were studied retrospectively. GER indices and apnea-related symptom association were measured by both MII-pH and conventional pH based analysis. Results: Of the total 998 GER episodes assessed by MII-pH monitoring, 407 (40.8%) were acidic and 590 (59.1%) were weakly acidic. A total of 1689 GER episodes were detected by conventional pH based analysis and 270 (16%) were related to retrograde bolus movement. A total of 313 apnea-related symptoms were reported. Five patients had a positive symptom association: 3 by MII-pH, 1 by both MII-pH and conventional pH, 1 only by conventional pH. Conclusions: Addition of MII-pH monitoring to conventional pH monitoring improves the diagnostic yield of symptom association analysis in preterm infants and neonates with apnea-related symptoms. Conventional pH monitoring is still important in the era of impedance measurement.

Diagnosis of supra-esophageal gastric reflux: correlation of oropharyngeal pH with esophageal impedance monitoring for gastro-esophageal reflux

Oropharyngeal (OP) pH monitoring has been developed as a new way to diagnose supra-esophageal gastric reflux (SEGR), but has not been well validated. Our aim was to determine the correlation between OP pH and gastro-esophageal reflux (GER) events detected by multichannel intraluminal impedance-pH (MII-pH). Fifteen patients (11 males, median age 10.8 years) with suspected GER were prospectively evaluated with ambulatory 24-h OP pH monitoring (positioned at the level of the uvula) and concomitant esophageal MII-pH monitoring. Potential OP events were identified by the conventional pH threshold of <4 and by the following alternative criteria: (i) relative pH drop >10% from 15-min baseline and (ii) absolute pH drop below thresholds of <5.5, 5.0, and 4.5. The 2-min window preceding each OP event was analyzed for correlation with an episode of GER detected by MII-pH. A total of 926 GER events were detected by MII-pH. Application of alternative pH criteria increased the identification of potential OP pH events; however, a higher proportion of OP events had no temporal correlation with GER (45-81%), compared with the conventional definition of pH < 4 (40%). A total of 306 full-column acid reflux episodes were detected by MII-pH, of which 10 (3.3%) were also identified by OP pH monitoring. Use of extended pH criteria increased the detection of potential SEGR events, but the majority of decreases in OP pH were not temporally correlated with GER. Oropharyngeal pH monitoring without concurrent esophageal measurements may overestimate the presence of SEGR in children.

Reflux patterns in patients with short‐segment Barrett’s oesophagus: a study using impedance‐pH monitoring off and on proton pump inhibitor therapy

In short-segment Barrett's oesophagus (SSBO) heartburn may be absent and oesophageal acid exposure time (OAET) assessed with pH-only monitoring may be normal. By detecting reflux episodes independently of their acidity, multichannel intraluminal impedance-pH (MII-pH) monitoring allows a comprehensive characterization of reflux events, either off or on proton pump inhibitor (PPI) therapy. To assess reflux parameters by MII-pH monitoring in newly diagnosed SSBO, at baseline and as modified with PPI therapy. Short-segment Barrett's oesophagus was defined by oesophageal intestinal metaplasia up to 3 cm in length. 24-h MII-pH monitoring was performed before and during PPI therapy. Fifty patients were studied prospectively. Normal OAET was found at baseline in 15 patients (30%), 8 and 2 of whom with a higher than normal number of acid and weakly acidic refluxes, respectively. Overall, abnormal reflux parameters were detected by MII-pH monitoring in 90% of patients. Reflux events were prevalent in the upright period. On PPI therapy, acid refluxes decreased and a correspondent increase in weakly acidic refluxes was observed (median from 48.5 to 9 and from 16 to 57.5, respectively) (P < 0.001). Acid refluxes, mainly in the upright period, characterize SSBO. PPI therapy transforms acid refluxes into weakly acidic refluxes.

Association of Gastroesophageal Reflux and O2 Desaturation: A Novel Study of Simultaneous 24-h MII–pH and Continuous Pulse Oximetry

BackgroundProof of the relationship between gastroesophageal reflux disease (GERD) and respiratory symptoms remains a challenge. Our aim was to determine the association between reflux events and O2 desaturation in GERD patients with primary respiratory symptoms (RS) compared to those with primary esophageal symptoms (ES) using ambulatory monitoring systems. MethodsOne thousand eight hundred fifty-one reflux episodes were detected by multichannel intraluminal impedance (MII)–pH testing in 30 patients with symptoms of GERD (20 RS, ten ES.) All patients underwent simultaneous 24-h MII–pH and continuous O2 saturation monitoring via pulse oximetry. Reflux-associated desaturation events were determined by correlating synchronized 24-h esophageal pH and/or impedance and O2 desaturation. ResultsOne thousand one hundred seventeen reflux events occurred in patients with RS and 734 in those with ES. Nearly 60% of these 1,851 reflux events were associated with O2 desaturation. Markedly more events were associated with O2 desaturation in patients with RS (74.5%, 832/1,117) than in patients with ES (30.4%, 223/734, p < 0.0001). The difference in reflux desaturation association was more profound with proximal reflux—80.3% with RS vs. 29.4% with ES (p < 0.0001). ConclusionsA remarkably high prevalence of O2 desaturation associated with gastroesophageal reflux was noted in patients with RS. Given further study, simultaneous combined esophageal reflux and O2 saturation monitoring may prove a useful diagnostic tool in this difficult group of patients.

Esophageal Motility in Nonacid Reflux Compared with Acid Reflux

Esophageal motility has been well studied in gastroesophageal reflux disease (GERD) and acid reflux, but not in nonacid reflux. Consecutive patients who had both 24-h multichannel intraluminal impedance-pH (MII-pH) and esophageal motility tests for suspected GERD were studied. Patients were grouped into nonacid refluxers, acid refluxers, and nonrefluxers based on positive symptom correlation and objective findings of acid reflux. Of 96 patients enrolled, 21 patients (22%) were nonacid refluxers, 44 patients (46%) were acid refluxers, and 31 patients (32%) had no objective evidence of reflux. Normal motility was recorded in 86% of nonacid refluxers, 71% of acid refluxers, and 60% of nonrefluxers. Ineffective esophageal motility was seen in 24% of acid refluxers, and 5% of nonacid refluxers (P = 0.11). Symptomatic nonacid reflux events comprised 22% of patients studied for GERD symptoms by MII-pH. Esophageal motility in nonacid reflux is normal 86% of the time.

Altered Esophageal Motility and Gastroesophageal Barrier in Patients with Jejunal Interposition After Distal Esophageal Resection for Early Stage Adenocarcinoma

IntroductionLimited resection of the esophagogastric junction has been proven to be safe and oncologically radical in patients with early esophageal cancer. Reconstruction with interposition of isoperistaltic jejunal loop (Merendino procedure) is supposed to prevent gastroesophageal reflux and therefore the recurrence of intestinal metaplasia at the anastomosis. The aim of this study was to assess the frequency of acid and nonacid refluxes after Merendino procedure using multichannel intraluminal impedance-pH (MII-pH) monitoring. Patients and MethodsBetween 2002 and 2005, 12 patients with esophageal adenocarcinoma underwent limited resection and jejunal interposition. Ten patients agreed to undergo a Gastrointestinal Symptom Rating Scale assessment, upper gastrointestinal (GI) endoscopy, esophageal manometry, and combined 24-h MII-pH monitoring more than 10 months postoperatively. ResultsPostoperatively, 4 (40%) patients reported belching without heartburn or acid regurgitation, 3 of them having a positive symptom index during 24-h MII-pH monitoring. Upper GI endoscopy revealed no inflammation, metaplasia, or stenosis at the esophagojejunal anastomosis. Esophageal manometry showed ineffective esophageal motility in four of ten patients. Combined 24-h MII-pH monitoring revealed normal distal esophageal acid exposure (% time pH < 4: 0.1% [0–1.5]), normal number of acid reflux episodes (3 [0–11]) but a high number of nonacid reflux episodes (82 [33–184]). Overall, eight patients revealed an abnormal number of nonacid reflux episodes. ConclusionThe limited resection with jejunal interposition for early esophageal cancer is efficient in controlling acid but not nonacid reflux. While the clinical relevance of nonacid reflux in the recurrence of Barrett’s esophagus is currently unknown, endoscopic surveillance should be considered in these patients.

Multichannel intraluminal impedance to detect relationship between gastroesophageal reflux and apnoea of prematurity

Background The association between gastroesophageal reflux and apnoea of prematurity is still controversial. Available data are biased by the heterogeneity of the infants enrolled as regard to some confounding factors and by the use of the traditional pH monitoring that is unable to detect non acid reflux events which might be prevalent in infants receiving frequent milk feeding. Multichannel intraluminal impedance has been recently introduced as a pH-independent method to investigate the bolus transport in hollow organs. Objective To assess if combined multichannel intraluminal impedance-pH study could be useful to detect an association between gastroesophageal reflux and apnoea of prematurity. Methods We prospectively evaluated a group of premature infants with apnoea of prematurity in absence of any confounding factors (ventilatory support, treatment with caffeine, permanent nasogastric tube, post-natal age older than 30 days) by simultaneous recording of 24-h multichannel intraluminal impedance-pH and cardiorespiratory monitoring. A temporal relationship between an apnoea and a reflux event was considered if both commenced within 20 s of each other. Results Six premature infants [three male; median gestational age 31 weeks (range 27–36); birth weight 1335 g (range 1200–2350); age at study 17 days (range 7–28)] were studied. A total of 405 reflux events [306 (76%) weakly acid and 99 acid reflux] and 142 apnoeas were detected. The frequency of apnoeas occurring during the reflux events period was significantly greater than the one calculated for reflux-free period [0.42/min (0.00–1.28) versus 0.016/min (0.003–0.028); p < 0.05]. The sub-analysis based on chemical composition and duration of refluxate showed that the frequency of apnoeas associated with weakly acid reflux events was significantly greater than the one calculated for reflux-free period [0.416/min (0.00–1.30) versus 0.016/min (0.003–0.028), respectively; p < 0.05] and that the frequency of apnoeas occurring during reflux events longer than 30 s was significantly higher than those occurring during shorter reflux events (22% versus 11%; p < 0.004). Conclusion Our data show that weakly acidic reflux events are more prevalent than acid reflux events in premature infants, confirming the need for the use of multichannel intraluminal impedance-pH monitoring for diagnosis of gastroesophageal reflux in those patients. Gastroesophageal reflux and apnoea of prematurity are both common occurrences and, in our experience, may be temporally related especially as regard to weakly acid refluxate and reflux events longer than 30 s.