Multichannel intraluminal impedance and pH monitoring in gastroesophageal reflux disease

The role of acid is very well established in the pathogenesis of gastroesophageal reflux disease and acid suppression constitutes the main approach to its medical treatment. With the current frequent use of proton pump inhibitors, we are seeing increasing numbers of patients in whom symptoms persist despite pharmacological acid suppression. Reflux monitoring has been traditionally performed through esophageal pH measurement to detect acid reflux (i.e., drops in esophageal pH to below 4.0). Multichannel intraluminal impedance and pH measurement constitutes an important development in reflux monitoring because, in addition to detecting acid reflux, it enables measurement of nonacid reflux (i.e., with a pH > 4.0, also known as ‘weakly acidic’ for pH > 4 but < 7, or ‘weakly alkaline’ if pH > 7), which may be responsible for symptoms in some patients who are being treated with proton pump inhibitors. This review describes the approach to measuring nonacid reflux, the possible mechanisms responsible for symptoms due to this type of reflux, the clinical importance of this phenomenon and available treatment options; and the role of multichannel intraluminal impedance and pH monitoring in the evaluation of refractory gastroesophageal reflux disease.     

Multichannel intraluminal impedance in esophageal function testing and gastroesophageal reflux monitoring

Multichannel intraluminal impedance (MII) is a new technique for evaluating esophageal function and gastroesophageal reflux. This technique depends on changes in resistance to alternating current between two metal electrodes produced by the presence of bolus inside the esophageal lumen. Combined MII and manometry (MII-EM) provides simultaneous information on intraluminal pressure changes and bolus movement, whereas combined MII and pH (MII-pH) allows detection of pH episodes irrespective of their pH values (ie, acid and non-acid reflux). Combined MII-EM studies are performed very similarly to standard manometry. Based on studies in healthy volunteers and patients, combined MII-EM challenges current existing criteria that define the effectiveness of esophageal body function. Combined MII-pH testing brings a shift in gastroesophageal reflux testing paradigm. In MII-pH studies, reflux events are no longer detected by pH. Refluxate presence, distribution, and clearing are primarily detected by MII and simply characterized as acid versus non-acid based on pH change and as liquid, gas, or mixed based on MII. MII determines refluxate clearance time, whereas pH measures acid clearance time. MII-pH shows promise to become an important clinical tool, particularly to assess gastroesophageal reflux in the postprandial period and in patients with persistent symptoms on therapy and with atypical symptoms.     

Multichannel intraluminal impedance for the assessment of post-fundoplication dysphagia

Dysphagia often occurs after fundoplication, although its pathophysiology is not clear. We sought to better understand postfundoplication dysphagia by measuring esophageal clearance with multichannel intraluminal impedance (MII) along with more traditional work-up (manometry, upper gastrointestinal imaging [UGI], endoscopy). We evaluated 80 consecutive patients after laparoscopic fundoplication between April 2002 and November 2004. Patients were evaluated clinically and underwent simultaneous manometry and MII, 24-hour pH monitoring, endoscopy, and UGI. For analysis, patients were divided into the following groups based on the presence of dysphagia and fundoplication anatomy (by UGI/endoscopy): (1) Dysphagia and normal anatomy; (2) Dysphagia and abnormal anatomy; (3) No dysphagia and abnormal anatomy; and (4) No dysphagia and normal anatomy. Patients with dysphagia (Groups 1 & 2) had similar peristalsis (manometry), but were more likely to have impaired clearance by MII (32 pts, 62%) than those without dysphagia (9 pts, 32%, P = 0.01). Patients with abnormal anatomy (Groups 2 & 3) were also more likely to have impaired esophageal clearance (66%vs. 38%, P = 0.01). Finally, of patients that had normal fundoplication anatomy, those with dysphagia were much more likely to have impaired clearance (12 pts, 52%) than those with dysphagia (4 pts, 21%, P = 0.03). MII after fundoplication provides objective evidence of esophageal clearance, and is commonly abnormal in patients with abnormal fundoplication anatomy and/or dysphagia. Esophageal clearance is impaired in the majority of patients with postoperative dysphagia, even with normal fundoplication anatomy and normal peristalsis. MII may detect disorders in esophageal motility not detected by manometry.     

Multichannel intraluminal esophageal impedance: a new frontier in motility]

Multichannel intraluminal impedance is a new technique for evaluating esophageal function and gastroesophageal reflux disease (GERD). This technique relies on the monitoring of electric conductivity in the esophagus though electrodes, and on changes developing in this variable as a result of bolus passage. The proximal distribution and duration of non-acid reflux events can now be quantified, and combined manometry defines the effectiveness of esophageal body function, until now only indirectly evaluated with pH changes. We discuss the case of a woman with persistent cough in whom intraesophageal multichannel impedance demostrates a minor acid reflux that could not be demonstrated with other diagnostic methods previously, and how this technique excludes any association between cough and non-acid reflux.     

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 20s of each other. RESULTS: Six premature infants [three male; median gestational age 31 weeks (range 27-36); birth weight 1335g (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 30s 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 30s.     

Multichannel intraluminal impedance and esophageal manometry data for unrestricted swallowing: establishing normal values

SUMMARY.    Standard esophageal manometric testing evaluates swallowing in the supine position using small boluses, with a recovery period imposed between swallows. Manometric tests of more physiologic unrestricted swallowing have had limited practical application due to highly variable results. The purpose of this study is to apply multichannel intraluminal impedance and manometry (MII-EM) to test esophageal function during unrestricted upright meal consumption, and to assess results in a normal healthy population. Ten healthy volunteers with normal esophageal impedance and manometry by published criteria underwent MII-EM testing using a combined 5-channel catheter. After transnasal placement of the catheter, each subject sat upright and consumed a meal that consisted of two pieces of toasted bread and two ounces of Gatorade. There were no restrictions placed on chewing, swallowing, or eating time. All data assessed by the MII-EM meal test were normally distributed. Impedance results with limited variability included the meal duration, number of swallows, postprandial emptying time and the percent of bolus presence times at 15, 10, and 5 cm above the lower esophageal sphincter. Manometric results with limited variability included the number of peristaltic sequences, mean time between these sequences and their distal esophageal amplitudes. MII-EM can be used to collect data with minimal variability in healthy subjects during unrestricted upright meal consumption. This technique may be used to identify abnormal motility patterns during physiologic swallowing.     

The importance of multichannel intraluminal impedance in the evaluation of children with persistent respiratory symptoms

OBJECTIVES: Previous evidence suggests an association between gastroesophageal reflux disease and chronic respiratory disease in children. Despite antisecretory antacid therapy, respiratory symptoms often persist supporting a role for nonacid reflux. The aim of this study was to determine whether nonacid reflux occurs in children with chronic respiratory disease. METHODS: Twenty-eight children (mean age: 6.5 +/- 5.6 yr) with persistent respiratory symptoms on antacid medications underwent 24 h pH/multichannel intraluminal impedance (pH/MII) recording. The symptom index (SI) and the symptom sensitivity index (SSI) were calculated for each patient. Logistic regression was performed to determine which reflux characteristics were associated with a high degree of symptom correlation present during the occurrence of symptoms. RESULTS: A total of 1,822 reflux episodes were detected by pH/MII, 45% of which were nonacidic. The mean SI increased using pH/MII (35.7 +/- 28.5) compared to pH probe alone (14.6 +/- 18.9; p= 0.002); no differences in the mean SSI using pH/MII compared to pH probe alone were identified. Significantly more patients had a positive SI using pH/MII than pH probe alone (p= 0.035); there was no difference in the number of patients with a positive SSI using pH/MII compared to pH probe alone. Multivariate analysis revealed that symptoms occurred more frequently when the reflux was nonacidic, mixed, and full column. Also, younger children were more likely to have the simultaneous occurrence of symptoms and reflux. CONCLUSIONS: Nonacid reflux may be an important predictor of respiratory symptoms. pH/MII provided important information in the evaluation of children with intractable respiratory symptoms.     

Oesophageal intraluminal impedance can identify subtle bolus transit abnormalities in patients with mild oesophagitis

In a subgroup of patients with non-erosive gastroesophageal reflux disease (GORD) or mild oesophagitis, acid clearance is prolonged in spite of favourable gravity and normal or minimally impaired oesophageal peristalsis. Dysphagia is rare in this group but might also be present or develop after anti-reflux surgery. The causal relationship between prolonged clearance or dysphagia and oesophageal body dysmotility in these patients is not completely clear. New techniques are now available to assess oesophageal motility and transit and might help to detect more subtle defects underlying functional impairment in patients with GORD. Combined video-fluoroscopy and intraluminal impedance indicate an excellent correlation between both methods in detecting oesophageal bolus transit. Combined intraluminal impedance and manometry has the capability to evaluate oesophageal contractions and bolus transit without the use of radiation. Subtle bolus transit abnormalities were identified in a small proportion of patients with mild oesophagits and normal oesophageal peristalsis. Outcome data are needed to evaluate the prognostic value of combined manometry-impedance in patients with GORD undergoing anti-reflux surgery.     

Combined multichannel intraluminal impedance and pH monitoring is helpful in managing children with suspected gastro-oesophageal reflux disease

BackgroundGastro-oesophageal reflux is very common in the paediatric age group. There is no single and reliable test to distinguish between physiologic and pathological gastro-oesophageal reflux, and this lack of clear distinction between disease and normal can have a negative impact on the management of children.AimsTo evaluate the usefulness of 24-h oesophageal pH-impedance study in infants and children with suspected gastro-oesophageal reflux disease.MethodsPatients were classified by age groups (A–C) and reflux-related symptoms (typical and atypical). All underwent pH-impedance study. If the latter suggested an abnormal reflux, patients received therapy in accordance with NASPGHAN/ESPGHAN recommendations, while those with normal study had an additional diagnostic work-up. The efficacy of therapy was evaluated with a specific standardized questionnaire for different ages.ResultsThe study was abnormal in 203/428 patients (47%) while normal in 225/428 (53%). Of those with abnormal study, 109 exhibited typical symptoms (54%), and 94 atypical (46%). The great majority of the patients with abnormal study were responsive to medical anti-reflux therapy.ConclusionsWe confirm the utility of prolonged oesophageal pH-impedance study in detecting gastro-oesophageal reflux disease in children and in guiding therapy. Performing oesophageal pH-impedance monitoring in children with suspected gastro-oesophageal reflux disease is helpful to establish the diagnosis and avoid unnecessary therapy.     

多通道食管腔内阻抗-pH监测对胃食管反流性咳嗽的诊断价值

 目的 探讨多通道食管腔内阻抗-pH监测（MII-pH）对胃食管反流性咳嗽（GERC）的诊断价值和局限性。方法 选择2010年5月—2011年7月在同济大学附属同济医院呼吸内科门诊就诊的可疑GERC患者,进行MII-pH,并经药物抗反流治疗证实诊断。分析MII-pH对GERC诊断的灵敏度、特异度、假阳性率、假阴性率、总符合率、阳性预计值和阴性预计值,并计算AUC_ROC和Kappa值。结果 在接受MII-pH的56例患者中,35例结果阳性,30例（85.7%）确诊为GERC,其中酸反流引起者25例（83.3%）,非酸反流引起者5例（16.7%）。在21例MII-pH阴性结果患者中,有6例（28.6%）经药物抗反流治疗,GERC诊断得到证实。MII-pH对GERC的诊断灵敏度为83.3%,特异度75.0%,假阳性率25.0%,假阴性率16.7%,总符合率80.4%,阳性预测值85.7%,阴性预测值71.4%,AUC_ROC 0.792,Kappa值0.577。结论 MII-pH能识别包括非酸反流在内的所有GERC,是较灵敏可靠的GERC诊断手段。     

Combined multichannel intraluminal impedance and pH monitoring assists the diagnosis of sliding hiatal hernia in children with gastroesophageal reflux disease

Background

The role of combined multichannel intraluminal impedance and pH monitoring (MII-pH) in diagnosing sliding hiatal hernia in gastroesophageal reflux disease (GERD) children remains unclear. We aimed to explore the clinical efficacy of MII-pH as a supplement diagnostic method for sliding hiatal hernia.

Methods

A total of 104 symptomatic GERD children [mean ± standard deviation (SD) age = 4.5 ± 5.5 years] were recruited. All of them were diagnosed as GERD with and without sliding hiatal hernia by barium and/or esophagogastroduodenoscopy study. All subjects received 24 h MII-pH monitoring to test the efficacy of this new modality.

Results

Sixteen children were diagnosed to have sliding hiatal hernia, and nine (56.3 %) of them received fundoplication. None of non-hiatal hernia children were indicated for fundoplication [risk difference (RD) 0.56; P < 0.001]. Impedance probes detected more reflux episodes than pH-probe in the whole study population (mean ± SD = 62.1 ± 47.8 vs. 47.8 ± 48.1 episodes; P = 0.02, paired t test). Due to the presence of pH-only reflux, the reflux episodes detected by impedance probes is less than that by pH probe in sliding hiatal hernia children (mean ± SD = 49.2 ± 78.9 vs. 103.7 ± 60.4 episodes; P = 0.01, paired t test). Ratio of reflux episodes detected by pH-probe to that by impedance probes >1 was more frequently noted in sliding hiatal hernia children than non-sliding hiatal hernia children (Odds ratio 58.33, P < 0.001). The sensitivity and specificity of this diagnostic tool to predict sliding hiatal hernia in GERD children are 93.8 and 79.6 %, respectively.

Conclusions

Ratio of reflux episodes detected by pH-probe to that by impedance probes >1 demonstrated by MII-pH study is a good screening test of sliding hiatal hernia in GERD children.     

Evaluation of esophageal function in patients with esophageal motor abnormalities using multichannel intraluminal impedance esophageal manometry

INTRODUCTION Esophageal manometry has been considered the “gold standard” test for the evaluation of esophageal motility. Esophageal manometry allows physicians to assess peri- stalsis by using informations about the shape, amplitude and duration of the…     

Characteristics of nighttime reflux assessed using multichannel intraluminal impedance pH monitoring and a portable electroencephalograph

Gastroesophageal reflux disease (GERD) is strongly associated with sleep disturbances. Although the mechanisms of this association have not been fully elucidated, nighttime reflux plays a central role. However, the detailed characteristics of nighttime reflux occurring during sleep are unknown. The aim of the present study was to examine the characteristics and prevalence of nighttime reflux in the natural sleep environment of GERD patients. Seventeen patients experiencing daily moderate‐to‐severe heartburn and/or regurgitation were studied using multichannel intraluminal impedance pH monitoring and electroencephalography off‐proton pump inhibitor treatment. Nighttime reflux was divided based on reflux type (liquid or gas), acidity (acidic, weakly acidic, or alkaline) and extent (distal only or proximal migration) according to the standard criteria. Nighttime phases were divided as follows: recumbent‐awake before falling asleep, nonrapid eye movement, rapid eye movement, awakening from sleep, and post‐awakening in the morning. Among 184 nighttime refluxes, 43 (23%) occurred during recumbent‐awake before falling asleep, 28 (15%) during nonrapid eye movement, 14 (8%) during rapid eye movement, 86 (46%) during awakening from sleep, and 13 (7%) during post‐awakening in the morning. Liquid reflux was more common in awakening during sleep (92%), nonrapid eye movement (100%), and rapid eye movement (100%) compared with awakening before falling asleep (68%). The prevalence of proximal migration was significantly lower in nonrapid eye movement and rapid eye movement than in the other phases. There were no differences in acidity and bolus clearance time among the phases. Thirteen (65%) of 20 events with GERD symptoms had nighttime reflux, suggesting that only 7.1% (13 of 184) of nighttime refluxes were symptomatic. Nighttime reflux was observed in 48 (11%) of 425 awakening episodes during sleep. Different reflux patterns at each phase during nighttime might explain the pathogenesis of GERD and its related sleep disturbances.     

The sensitivity of multichannel intraluminal impedance and the pH probe in the evaluation of gastroesophageal reflux in children.

BACKGROUND & AIMS: Multichannel intraluminal impedance (MII) has been incorporated into gastroesophageal reflux evaluations in children despite a lack of evidence comparing it to the gold standard pH probe. The aim of this study was to compare these two technologies. METHODS: Twenty-five consecutive, untreated children undergoing pH-MII recording were studied. Sensitivities for the pH probe and MII were defined as: (acid+pH-only episodes)/(acid+non-acid+pH-only episodes) and (acid+non-acid episodes)/(acid+non-acid+pH-only episodes), respectively. Sensitivities were compared using paired t testing. After the analysis was performed, the pH-MII tracings of 25 age-matched children taking acid suppression therapy were compared and sensitivity calculations were performed. RESULTS: In untreated patients, 1845 reflux episodes were detected, and 1702 were detected in treated patients. The mean sensitivities of pH probe and MII in untreated patients were 80.6 +/- 18.2% and 76.1 +/- 13.5%, respectively (P = .41). The mean sensitivities of pH probe and MII in treated patients were 47.2 +/- 36.0% and 80.3 +/- 21.1%, respectively (P = .005). Twenty-five percent of reflux episodes were pH-only episodes. There were no differences in the mean number of acid or non-acid reflux episodes in patients with normal and abnormal pH probe studies. Instead, there were significantly more pH-only episodes in patients with abnormal probe studies. CONCLUSIONS: The sensitivity of MII equals that of the pH probe in untreated patients but is superior to the pH probe in treated patients. pH-only episodes are numerous in pediatrics and should be included in pH-MII analyses.     

Aerophagia, gastric, and supragastric belching: a study using intraluminal electrical impedance monitoring

BACKGROUND: Patients with aerophagia are believed to have excessive belches due to air swallowing. Intraluminal impedance monitoring has made it possible to investigate the validity of this concept. METHODS: The authors measured oesophageal pH and electrical impedance before and after a meal in 14 patients with excessive belching and 14 healthy controls and identified patterns of air transport through the oesophagus. The size of the gastric air bubble was measured radiographically. In four patients prolonged oesophageal manometry was performed simultaneously. RESULTS: In all subjects, impedance tracings showed that a significant amount of air is propulsed in front of about a third of the swallow induced peristaltic waves. Two types of retrograde gas flow through the oesophagus (belch) were observed. In the first type air flowed from the stomach through the oesophagus in oral direction ("gastric belch"). In the second type air entered the oesophagus rapidly from proximal and was expulsed almost immediately in oral direction ("supragastric belch"). The incidence of air-containing swallows and gastric belches was similar in patients and controls but supragastric belches occurred exclusively in patients. There was no evidence of lower oesophageal sphincter relaxation during supragastric belches. Gastric air bubble size was not different between the two groups. CONCLUSIONS: In patients with excessive belching the incidence of gaseous reflux from stomach to oesophagus is similar to that in healthy subjects. Their excess belching activity follows a distinct pattern, characterised by rapid antegrade and retrograde flow of air in the oesophagus that does not reach the stomach.     

经胸阻抗监测在慢性心力衰竭患者中的临床应用观察

目的评估植入性器械经胸阻抗监测功能识别慢性心力衰竭患者中液体潴留的有效性。方法对10例植入带有经胸阻抗监测功能植入式器械的慢性心力衰竭患者进行定期随访,观察经胸阻抗的变化,并分析其可能原因。结果10例患者出现经胸阻抗的变化并达液体潴留报警阈值水平4例共7次报警,生活方式变化、停用抗心力衰竭药物、感染及再次植入术引起各1次,另3次为心功能下降所致。结论经胸阻抗监测在慢性心力衰竭患者中是一项有用的工具,能尽早预警心力衰竭患者的失代偿。