Intraluminal impedance: an ideal technique for evaluation of pediatric gastroesophageal reflux disease

Multichannel Intraluminal Impedance and pH Monitoring: A Step Towards Pediatric Reference Values

Background/Aims

Combined multichannel intraluminal impedance and pH monitoring (MII/pH) is considered the most accurate test to detect gastroesophageal reflux (GER), however lacking reference values. We aim to determine reference values for the pediatric population and to correlate these values with age and postprandial/fasting period.

Methods

We evaluated MII/pH traces from patients (newborns, infants, and children) admitted to 3 Italian hospitals and who underwent MII/ pH for suspected GER disease. Patients with MII/pH traces that showed significant symptom-reflux associations and/or a pathological reflux index (> 6% for newborns and infants, > 3% for children) were excluded. Traces were analysed in their entirety, and in the postprandial period (first hour after a meal) and the fasting period (the following hours before the next meal) separately.

Results

A total of 195 patients (46 newborns, 83 infants, and 66 children) were included. Age positively correlated with frequency of acidic GER events (r = 0.37, P < 0.05) and negatively associated with weakly acidic GER events (r = 0.46, P < 0.05).

Conclusions

This study describes the distribution of MII/pH values in a pediatric population with normally acidic GER exposure and no significant association between GER events and symptoms. These MII/pH values may be used as reference values in clinical practice for a corrected GER disease diagnosis in the pediatric population.

Esophageal Bolus Transit in Newborns with Gastroesophageal Reflux Disease Symptoms: A Multichannel Intraluminal Impedance Study

PURPOSE

The aim of this study was to evaluate bolus transit during esophageal swallow (ES) and gastroesophageal reflux (GER) events and to investigate the relationship between the characteristics of ES and GER events in a population of term and preterm newborns with symptoms of gastroesophageal reflux disease (GERD).

METHODS

The study population consisted of term and preterm newborns referred to combined multichannel intraluminal impedance (MII) and pH monitoring for GERD symptoms. The frequency and characteristics of ES and GER events were assessed by two independent investigators. Statistical significance was set at p<0.05.

RESULTS

Fifty-four newborns (23 preterm) were included in the analyses. Median bolus head advancing time corrected for esophageal length (BHATc) was shorter during mealtime than during the postprandial period (median, interquartile range): 0.20 (0.15-0.29) s/cm vs. 0.47 (0.39-0.64) s/cm, p<0.001. Median bolus presence time (BPT) was prolonged during mealtime: 4.71(3.49-6.27) s vs. 2.66 (1.82-3.73) s, p<0.001. Higher BHATc (p=0.03) and prolonged BPT (p<0.001) were observed in preterm newborns during the postprandial period. A significant positive correlation between BHATc and bolus clearance time was also observed (ρ=0.33, p=0.016).

CONCLUSION

The analysis of ES and GER events at the same time by MII provides useful information to better understand the physiopathology of GERD. In particular, the analysis of BHATc during the postprandial period could help clinicians identify newborns with prolonged esophageal clearance time due to impaired esophageal motility, which could allow for more accurate recommendations regarding further tests and treatment.

A new method to estimate catheter length for esophageal multichannel intraluminal impedance monitoring in children

BACKGROUND

Multichannel intraluminal impedance combined with pH (MII-pH) is the gold standard test for diagnosing gastro-esophageal reflux disease (GERD). It provides an opportunity to study acid and non-acid GOR and temporal association between symptoms and reflux. Accurate catheter placement is essential to prevent erroneous recording of reflux events. The aims of our study were to assess the accuracy of our devised method in predicting the catheter length for MII-pH in children (Great Ormond Street Hospital (GOSH) Table) and to compare the results with Strobel and Monreau methods.

METHODS

Retrospective review of all records of infants and children who underwent MII-pH studies between January to October 2014. Desired catheter position was calculated using Strobel, Monreau and GOSH formulas and compared to X ray position.

KEY RESULTS

One hundred and forty-four children were included; mean age was 5.1 (±4.5) years, 73 males and 71 females. In the whole group, the correlation between desired catheter position and GOSH Table was 0.95, for Strobel was 0.84, and Monreau was 0.85. In the first group (age <3 years), the correlation was: GOSH Table 0.91, Strobel 0.56, and Monreau 0.6; in the second group (3-10 years): GOSH Table 0.78, Strobel 0.82, and Monreau 0.82; the third group (>10 years): GOSH 0.81, Strobel 0.43, and Monreau 0.43.

CONCLUSIONS & INFERENCES

GOSH Table is an accurate method to estimate the insertion length of MII-pH catheters from nares to a point of approximately two vertebral bodies above the diaphragm in children. Although radiography is required to confirm final catheter position, using GOSH Table will reduce the need for repeated catheter manipulation after initial insertion and will reduce the use of a mathematically complicated formulae.

Can MII-pH values predict the duration of treatment for GERD in preterm infants?

BACKGROUND

Little is known regarding the prognostic role of Multichannel Intraluminal Impedance and pH monitoring (MII/pH) parameters in preterm infants with Gastro-Esophageal Reflux Disease (GERD).

AIM

Our study aimed to evaluate the relationship between MII/pH variables and the duration of pharmacological therapy for GERD, in preterm infants with gestational age (GA) ≤34weeks.

SUBJECTS, STUDY DESIGN, OUTCOME MEASURES

We retrospectively reviewed data of all newborns with GA ≤34weeks that underwent MII/pH in our Neonatal Intensive Care Unit (NICU) and pharmacological treatment for GERD. We included them in a 12-month follow-up program. MII/pH parameters were used as independent variables and the duration of pharmacological therapy as dependent variable in linear regression models.

RESULTS

16 patients (GA 28.4±1.8weeks, BW 1122±427g) were enrolled into the study. Regression analysis performed on all reflux events reported a significant correlation between the duration of pharmacological treatment and MII-BEI (r(2)=0.36, p=0.01) and MII-reflux frequency (r(2)=0.33, p=0.02). Moreover, regression analysis performed on all events classified according to the corresponding pH change - acidic (ac.), weakly acidic (w.ac.) or weakly alkaline (w.a.) - showed a significant correlation between the duration of pharmacological treatment and MII-w.ac.BEI (r(2)=0.26, p=0.05), MII-w.ac. reflux frequency (r(2)=0.44, p=0.01), and MII-proximal w.ac. reflux frequency (r(2)=0.35, p=0.02). No statistically significant correlation was found between pH-Reflux Index and the duration of treatment.

CONCLUSION

The study shows how, in our population of preterm infants, MII-parameters could have not only a diagnostic role, but also a prognostic value in terms of the duration of pharmacological treatment.

Prognostic values of multichannel intraluminal impedance and pH monitoring in newborns with symptoms of gastroesophageal reflux disease

OBJECTIVE

To evaluate the relationship between multichannel intraluminal impedance and pH monitoring (MII/pH) values in newborns with symptoms of gastroesophageal reflux disease (GERD) and clinical history in their first 3 years of life.

STUDY DESIGN

Sixty-four newborns with GERD symptoms who underwent MII/pH in the first weeks of life were enrolled into a clinical follow-up program. Follow-up visits were programmed at 1, 3, 6, 9, 12, 18, 24, and 36 months. Patients were divided into 3 groups according to duration of symptoms: short (1-3 months), medium (4-9 months), and long (>9 months), and MII/pH values in these groups were compared.

RESULTS

Fifty-three patients completed the 3-year follow-up. The number of patients with GERD symptoms decreased each month. A comparison of MII/pH values of the 3 lifetime symptom groups revealed differences in the impedance bolus exposure index (F = 83; P = .012) and proximal reflux frequency (F = 410; P = .022). These 2 MII variables showed an increasing trend from the short lifetime symptom group to the long lifetime symptom group. Weakly acidic reflux events, but not acidic events, were responsible for these differences.

CONCLUSION

MII/pH in newborns has prognostic value regarding the duration of GERD symptoms and provides useful information that clinicians may give parents about the prognosis of symptomatic infants. Impedance bolus exposure index and proximal reflux frequency seem to be the variables with the highest predictive value. Weakly acidic reflux events play an important role in determining the duration of GERD symptoms in newborns.

[Comparison between conventional ph measurement and multichannel intraluminal esophageal impedance in children with respiratory disorders]

INTRODUCTION

Gastroesophageal reflux (GER) is associated with respiratory symptoms. The link between non-acid GER and the pathogenesis of respiratory disease has been demonstrated. Esophageal multichannel intraluminal impedance (MII) is able to detect non-acid and alkaline GER, as well as reflux height. The objective of the study was to compare the diagnostic effectiveness of dual-channel pH-meter and MII.

PATIENTS AND METHODS

A prospective study was conducted on patients diagnosed with uncontrolled asthma, persistent cough, or chronic laryngitis. Patients were monitored continuously for 24 hours using a combination of MII and a dual-channel pH-meter. A descriptive and comparative analysis of the techniques was performed using the t test for comparison between groups and McNemar test for non-parametric data.

RESULTS

A total of 49 patients with respiratory disease between September 2008 and April 2010 (79.6% uncontrolled asthma, 10.2% persistent cough, and 10.2% chronic laryngitis) were included in the study. The mean number of refluxes detected was 18.3 (range 0-93) using the pH-meter and 39.2 (11-119) using MII (P<.001). Acid GER was detected using pH in 7 children and using MII in 25 children (8 acid, 10 alkaline and 7 mixed). A mean of 21 proximal refluxes were detected using MII.

CONCLUSIONS

MII makes it possible to diagnose a greater number of refluxes, whether acid or alkaline, than conventional pH measurement in children with respiratory disease that is poorly controlled with their usual treatment. MII can also detect proximal refluxes.

Combined oesophageal impedance-pH monitoring in preterm newborn: comparison of two options for layout analysis

Gastro-oesophageal reflux (GOR) is common in preterm infants. Combined multichannel intraluminal impedance and pH monitoring (pH-MII) is emerging as an useful tool to study both acid and non-acid GOR in this population. We aimed to highlight main advantages and limits of pH-MII in preterm infants and to test whether the inclusion of GOR episodes detected only by pH monitoring details better the features of GOR. Fifty-two symptomatic preterm infants underwent a 24-hour, continuous and simultaneous measurement of pH-MII. Each layout was analyzed using two different options: option 1 included GOR episodes detected by MII and then classified as acid or non-acid according to the associated pH change; option 2 included GOR episodes detected by MII and also GOR episodes detected only by pH sensor. By adopting option 1, a total number of 2834 GOR episodes was detected by MII: 2162 of them were characterized as non-acid and 672 were characterized as acid. The median (range) number of acid MII-GOR episodes was 10 (1-52); the median (range) number of non-acid MII-GOR episodes was 36.5 (2-119). Median (range) acid MII-GOR-bolus exposure index was 0.28% (0.02-2.73%); median (range) non-acid MII-GOR-bolus exposure index was 1.03% (0.06-38.15%). By adopting option 2, an average of 53.2 acid GOR episodes and an average of 11% oesophageal exposure to acid GOR more than by option 1 was detected. An accurate and detailed description of GOR in preterm infants can be obtained only by including in the analysis all acid GOR episodes detected by pH sensor.

Evaluation of gastroesophageal reflux in pediatric patients with asthma using impedance-pH monitoring

OBJECTIVES

To determine the proportion of acid and nonacid reflux events in children with asthma suspected to have gastroesophageal reflux (GER) using combined impedance-pH monitoring, and to determine the symptom index (SI) for nonacid and acid reflux events.

STUDY DESIGN

This was a prospective study of children with asthma (age 5 months to 6 years) referred for evaluation of GER. Exclusion criteria were congenital anomalies, cerebral palsy, mental retardation, and cardiac disease. The children underwent a 20-hour multichannel intraluminal impedance (MII)-pH study.

RESULTS

A total of 24 children (17 male; mean age, 33 months) were enrolled from March 2004 to February 2005. MII-pH detected 1184 reflux events, versus 419 reflux events by pH alone; 51% (605 events) were nonacid. The proportion of nonacid reflux events decreased with time elapsed from last meal (P < .0001 by Pearson's chi2 test). A total of 555 symptoms were recorded, including 331 cases of cough, 243 of which (73.4%) were not associated with a reflux event. The SI for MII-pH was significantly different than that for the pH probe (37% vs 0%; P = .008).

CONCLUSIONS

Acid and nonacid reflux occurs with equal frequency in children with asthma. Most symptoms occur in the absence of a reflux event.

Ultrasonographic study of postcibal gastro-esophageal reflux and gastric emptying in infants with recurrent respiratory disease

AIM

To check the utility of postcibal ultrasonography for the evaluation of reflux in relation to gastric emptying in infants with recurrent respiratory symptoms and to link imaging with clinical data.

METHODS

Esophageal reflux (hyperechoic retrograde filling) and gastric emptying (antral areas) were quantified before and after ingestion of a standard formula in 35 untreated infants (13 with chronic cough, 22 with recurrent bronchitis) and in 31 controls.

RESULTS

The prevalence of abnormal (> or =8 episodes) postcibal refluxes was 74% in patients and 3% in controls. Number, duration of the longest episode and extent of refluxes were significantly higher in patients compared to controls. Number of refluxes was higher in patients with symptomatic refluxes than in those without. Infants with recurrent bronchitis had more refluxes than those with chronic cough and controls. Extent and timing of gastric emptying were similar in patients and controls.

CONCLUSION

Esophageal ultrasonography is a useful and physiological test in infants with recurrent respiratory diseases, which have a high prevalence of abnormal postcibal esophageal reflux and a gastric emptying similar to that of normal controls. Esophageal reflux is more severe in subjects with recurrent bronchitis than in those with chronic cough.

Evaluation of infantile acid and nonacid gastroesophageal reflux using combined pH monitoring and impedance measurement

OBJECTIVE

Characterize the proportion of acid and nonacid esophageal reflux events in young infants with suspected gastroesophageal reflux (GER) using combined pH-multichannel intraluminal impedance (MII) monitoring. Determine the symptom index correlation with nonacid reflux and acid reflux events.

STUDY DESIGN

Prospective study of children, aged 2 weeks to 1 year, referred to The Children's Hospital of Denver Gastroenterology Clinic for evaluation of GER. Exclusion criteria were congenital anomalies or syndromes, cerebral palsy, mental retardation, and pulmonary or cardiac disease. The children were admitted to The Children's Hospital General Clinical Research Center for a 20 hour pH-MII study. Acid suppression was either never used or discontinued 2 weeks before testing.

RESULTS

Thirty-four infants were enrolled from February 2004 to February 2005. Ages ranged from 2 months to 11 months, median = 7 (20 females/14 males). One thousand eight hundred ninety reflux events were detected by MII, and 588 reflux events were detected by pH probe alone. The percent of reflux that was acid was 47% (888 events) versus 53% of (1,002 events) nonacid reflux events. The proportion of nonacid reflux decreased with age (P < 0.0001 by Pearson chi test) and with increasing time elapsed from last meal. There were 958 total symptoms evaluated. The most frequently reported symptom was fussiness/pain, which correlated with nonacid reflux events 24.6% and acid reflux 25.2%. The proximal height of a reflux was predictive for symptoms of fussiness/pain, arching, and burping.

CONCLUSION

MII detects more reflux events than pH monitoring alone. The proportion of nonacid reflux to acid reflux events in infants is more similar to adults than previously reported. Combined pH-MII esophageal monitoring identifies more reflux events and improves clinical correlation with symptoms.

Combined multichannel intraluminal impedance and pH-metry: a novel technique to improve detection of gastro-oesophageal reflux literature review

Ambulatory pH monitoring is currently the best method for detection of gastro-oesophageal reflux. However, pH electrodes are able to measure only acid reflux, and therefore, non-acid reflux episodes, a potentially important cause of symptoms, are ignored by this technique. Multichannel intraluminal electrical impedance has recently been proposed as a novel method to overcome the above limitation of pH testing. Impedance (expressed in ohms) is a measure of the total opposition to current flow between adjacent electrodes. As refluxed contents are characterised by different conductivity, which is the inverse of impedance, for the first time a pH-independent accurate and practical qualitative analysis of refluxate is possible. For instance, the conductivity of air is almost zero and then impedance increases compared with baseline, whereas the conductivity of liquid is much higher and the impedance curve decreases remarkably. The combination of electrical impedance with traditional pH monitoring has the only aim of differentiating acid from non-acid liquid reflux. Moreover, the impedance catheter contains multiple pairs of ring electrodes along the oesophagus, so that an exact assessment of the proximal extent of refluxed material can be achieved. From a clinical point of view, electrical impedance + pH-metry could be useful for identifying the number and percent times of gas, acid and non-acid reflux episodes, to improve the yield of symptom index, to evaluate the reasons for poor response of reflux symptoms to proton pump inhibitors and to know the proximal extent of reflux events in patients with atypical symptoms. Thus, this technique has the potential to become a useful tool for improving our knowledge of gastro-oesophageal reflux disease and optimising the management of these patients.

Pathophysiological mechanisms of gastroesophageal reflux disease in children

Gastroesophageal reflux (GER) is an extremely common pediatric problem, but only in the past few years have we developed a better understanding of its pathophysiology. This is related to the wider use of investigative tools such as flexible endoscopy, 24-hour pH monitoring, and more recently, micromanometric methods and noninvasive breath tests, which have been particularly useful in infants. This paper reviews our current understanding of the esophageal and gastric mechanisms contributing to the pathophysiology of GER. In this context, we also highlight areas where new therapeutic approaches may be beneficial.

Evaluation of gastroesophageal reflux events in children using multichannel intraluminal electrical impedance

The majority of gastroesophageal reflux (GER) episodes in infants and children are nonacidic (pH >4). However, extraesophageal symptoms (e.g., breathing irregularities, apnea, aspiration) apparently can be caused by both acidic (pH <4) and nonacidic reflux. The standard diagnostic tool for suspected GER is pH monitoring. However, physicians should be aware of the limitations of pH monitoring in the pediatric population, because most reflux episodes in this age group are undetectable by this method. In contrast, the pH-independent multiple intraluminal electrical impedance technique (IMP) allows all bolus movements in the esophagus to be detected. Data can be analyzed for bolus composition and reflux height, duration, and clearance. Combining IMP with pH monitoring on a single catheter has proved to be a valuable tool for diagnosing GER and associated symptoms in infants and children.

Effects of thickened feeding on gastroesophageal reflux in infants: a placebo-controlled crossover study using intraluminal impedance

OBJECTIVE

Thickening of formula feedings is part of the therapeutic approach for gastroesophageal reflux (GER) in infants. However, its mechanism of action, especially regarding the occurrence of nonacid (pH >4) GER, has not yet been clearly described. The aim of this randomized, placebo-controlled crossover study was to examine the influence of formula thickened with carob (St. John's bread) bean gum on acid and nonacid GER.

METHODS

Infants with recurrent regurgitation and without other symptoms were fed alternately (A-B-A-B-A-B) with thickened (A) and nonthickened (B) but otherwise identical formula. Documentation of GER episodes during the study was performed by simultaneous intraesophageal impedance measurement (intraluminal electrical impedance; IMP) and pH monitoring. The IMP technique is able to detect bolus movements inside a luminal organ. The use of multiple measuring segments on a single catheter allowed the analysis of direction, height, and duration of the bolus transport. Continuous videorecording and visual surveillance of regurgitation frequency and amount resulted in a severity score.

RESULTS

Fourteen infants (42 +/- 32 days old) were examined during 6 feeding intervals each for a total measuring time of 342 hours. A total of 1183 GER episodes and 83 episodes of regurgitation were registered. Regurgitation frequency (15 vs 68 episodes) and amount (severity score 0.6 vs 1.8) were significantly lower after feedings with thickened formula. The difference regarding the occurrence of GER documented by IMP was also pronounced (536 vs 647 episodes). Although not statistically significant, maximal height reached by the refluxate in the esophagus was decreased after thickened feedings. Mean GER duration and the frequency of acid (pH <4) GER were not altered.

CONCLUSIONS

Thickened feeding has a significant effect on the reduction of regurgitation frequency and amount in otherwise healthy infants. This effect is caused by a reduction in the number of nonacid (pH >4) GER episodes, but also because of a decrease of mean reflux height reached in the esophagus. However, the occurrence of acid GER is not reduced. The combination of IMP and pH monitoring allows the complete registration and description of these GER episodes. Thickening of formula feedings with carob bean gum is an efficient therapy for uncomplicated GER in infants.

Esophageal pH monitoring and impedance measurement: a comparison of two diagnostic tests for gastroesophageal reflux

BACKGROUND

pH monitoring is the standard diagnostic tool for gastroesophageal reflux in infants. However, this method does not document the reflux of all kinds of fluid from the stomach into the esophagus, but only documents acid material. The parameters that define reflux episodes by pH monitoring have been derived empirically from observations of many infants considered healthy and ill. Acid reflux is a continuum, some reflux is normal and doubt exists as to how much reflux is abnormal. In this study, one of the standardized protocols for analyzing pH recordings was evaluated and compared with simultaneously obtained intraesophageal impedance measurement (IMP), a pH-independent method of detecting bolus movement within the esophagus.

METHODS

The esophagi of 50 infants with reflux symptoms were measured, using both standard pH probe and multiple-site impedance measurement. A standard protocol for analyzing esophageal pH records was used. The sampling rate for pH values was 15/min. Acid reflux was defined as pH less than 4.0 (threshold pH) for at least 15 seconds (minimal duration) with at least 30 seconds (latency time) between separate episodes. The software used could adjust independently or in combinations the sampling rate and these reflux criteria. Thereby it was determined whether changes in the criteria for acid reflux improved the sensitivity and predictive value of pH monitoring when compared with reflux episodes defined by IMP.

RESULTS

During 318 hours of recording in 50 infants, 1,887 episodes of reflux occurred according to IMP. Only 282 (14.9%) of the IMP-determined episodes were acid reflux episodes. No alkaline reflux episodes occurred. Among the 270 pH probe-determined episodes using the standard criteria of acid reflux, only 153 (sensitivity, 54.3%; positive predictive value, 56.7%) were accompanied by unmistakable retrograde bolus movement using IMP measurements. Retrograde bolus movement did not accompany the other 117 episodes. Using a sampling rate of 15/min, a pH threshold of 4.0, a minimal duration of reflux episodes of 8 seconds, and a latency time of 60 seconds, the positive predictive value of pH probe results increased to 60.7%. Variations in the sampling rate or criteria for defining acid reflux did not significantly improve the accuracy of the pH probe results versus IMP-defined episodes.

CONCLUSIONS

Most reflux episodes that occur in infants are undetectable by standard pH probe monitoring. pH monitoring does not detect all reflux in the esophagus but is useful for detecting acidity in the esophagus and determining the duration of its presence. Combining pH monitoring with impedance measurement is a valuable diagnostic tool for gastroesophageal reflux in infants.

Chronic vomiting in children: New insights into diagnosis

Chronic vomiting disorders with diverse causes are seen in children of all ages and present diagnostic and therapeutic challenges to pediatric gastroenterologists. Most patients are diagnosed by history, physical examination, and a basic work-up aimed at excluding obstructive and inflammatory causes. Intractable cases warrant further evaluation for clarification of the diagnosis. This review focuses on the pathophysiology of vomiting and four of the syndromes manifesting as chronic vomiting. It also includes a detailed exploration of the new tools available for evaluation of these syndromes.