Will esophageal impedance replace pH monitoring?

Oral Care Associated With Less Microaspiration in Ventilated Cardiac Patients

Aspiration is common in mechanically ventilated patients and may predispose patients to aspiration pneumonia, chemical pneumonitis, and chronic lung damage. Pepsin A is a specific marker of gastric fluid aspiration and is often detected in ventilated pediatric patients. We investigated the effect of oral care and throat suctioning in the detection of pepsin A in tracheal aspirates (TAs) up to 4 hours after these procedures.

Methods

Twelve pediatric patients between age 2 weeks to 14 years who underwent intubation for cardiac surgery were enrolled in this study. Six of the 12 patients were consented before their surgery with initial specimen collected at the time of intubation and last one shortly before extubation (intubation duration < 24 hours). The remaining 6 patients were consented after cardiac surgery. All specimens were collected per routine care per respiratory therapy protocol and shortly before extubation (intubation duration > 24 hours). Tracheal fluid aspirates were collected every 4 to 12 hours in the ventilated patients. Enzymatic assay for gastric pepsin A and protein determination were performed. The time of oral care and throat suctioning within 4 hours prior was recorded prospectively.

Results

A total of 342 TA specimens were obtained from the 12 intubated pediatric patients during their course of hospitalization; 287 (83.9%) showed detectable total pepsin (pepsin A and C) enzyme activity (> 6 ng/mL) and 176 (51.5%) samples had detectable pepsin A enzyme levels (>6 ng/mL of pepsin A). Only 29 samples of 76 samples (38.2%) had evidence of microaspiration after receiving oral care, while 147 of 266 (55.3%) samples were pepsin A positive when no oral care was provided. Odds ratio is 0.50 (Cl 0.30-0.84), and the number needed to treat is 5.8 (Confidence interval 3.4-22.3). Testing air filters for pepsin was not beneficial.

Conclusion

Oral care is a highly effective measure to prevent microaspiration of gastric fluid in ventilated pediatric patients. The number needed to treat (5.8) suggests this is a very effective prevention strategy. Our study suggests that pepsin A is a useful and sensitive biomarker that allows identification of gastric aspiration.

Relationship between functional endoscopy and impedance-pH measurement

Classic gastroenterological diagnostic tools have proven to be insufficient in identifying the causal relationship between extra-esophageal symptoms and presumed pathological reflux activity. Some new methodological approaches, such as functional endoscopy (video panendoscopy, VPE), are considered to be helpful. However, there are currently no data objectively verifying the success of this method. In a previous study, we found a good correlation between the reflux symptom index (RSI) according to Belafsky and endoscopic findings. Impedance-pH measurement is considered to be the gold standard in esophageal reflux disease diagnostics. Therefore, the relationship between endoscopic findings and the results of impedance-pH monitoring is now studied in patients with extra-esophageal reflux symptoms. The pathological findings of the VPE correlate with impedance-pH measurements regarding the parameters "number of reflux episodes," "fraction time," and "DeMeester score."

[Relationship between functional endoscopy and impedance-pH measurement. German version]

Classic gastroenterological diagnostic tools are proving increasingly insufficient for analyzing the complex causal relationship between extra-esophageal symptoms and presumed pathological reflux activity. Some new methodological approaches, such as functional endoscopy (videopanendoscopy, VPE), are considered to be helpful. However, there are currently no data objectively verifying the usefulness of this method. In a pilot study, a good correlation between the reflux symptom index (RSI) and endoscopic findings was shown. Impedance-pH measurement is considered to be the "gold standard" in esophageal reflux disease diagnostics. Therefore, the relationship between endoscopic findings and the results of impedance-pH monitoring are now studied in patients with extra-esophageal reflux symptoms. The investigation demonstrates that the pathological findings of VPE correlate well with impedance-pH measurements in terms of the parameters "number of reflux episodes", "fraction time", and "DeMeester score".

The feasibility and efficacy of multi-channel intraluminal impedance monitoring in children

INTRODUCTION

The diagnosis of gastro-oesophageal reflux is currently based on clinical presentation and oesophageal pH monitoring. In recent years, the use of multi-channel intraluminal impedance (MII) monitoring has gained increasing attention in the adult population. However, its use in the paediatric population is still in the developing stage with only limited number of publications. This study aims to review our early experience of MII application in children.

METHODS

A retrospective study of all patients who underwent MII monitoring between 2011 and 2014 at a tertiary referral centre was performed. Patients' medical records were reviewed with demographic data extracted. Number of reflux episodes and other MII parameters were analysed.

RESULTS

In total, 34 patients were identified during the study period, with 20 males and 14 females. Indication for study included previous aspiration pneumonia (n = 13), persistent reflux or vomiting symptom (n = 10) and as part of routine assessment before gastrostomy (n = 11). At the time of study the average age was 69 months (range 9-216 months). 28 patients showed significant gastro-oesophageal reflux. On average patient has 36.1 acidic and 22.3 non-acidic reflux episodes during the 24 h monitoring period. Non-acidic reflux accounts for 38.1 % of the overall reflux episodes. The sensitivity of MII monitoring to detect reflux was higher compared to conventional pH study (73 vs 50 %, p = 0.1).

CONCLUSION

MII monitoring is safe and feasible in children. Non-acid reflux should not be underestimated in paediatric population. MII appears to be more sensitive than conventional pH monitoring in our study, but its true significance is yet to be confirmed by larger study in the future.

Incidence of use of acid suppression medications in infants with oral clefting

OBJECTIVE

Less than 1% of the general pediatric population needs pharmacologic therapy for reflux symptoms; yet, the co-existence of gastroesophageal reflux disease (GERD) with oral clefting remains unclear. The purpose of this retrospective study was to appreciate the difference in the incidence of anti-GERD pharmacotherapy in a sample population of infants with oral clefting compared to the general pediatric population.

MATERIALS AND METHODS

One hundred ninety-six consecutive patients diagnosed with cleft lip only, cleft lip and palate, and isolated cleft palate were analyzed through clinical record review. Demographic and clinical information including but not limited to the type of oral cleft present at birth, reported signs and symptoms of GERD, and anti-GERD medications used were compiled for all subjects. Collected data were analyzed using descriptive statistics.

RESULTS

Sixty-four (33%) of 196 infants with oral clefts had documented signs and symptoms of GERD. Nine percent (18 of 196) of the subjects received anti-GERD medications. The infant subgroup with treated GERD consisted of 11 out of 62 (18%) patients with isolated cleft palate, 5 of 112 (4.5%) with cleft lip and palate, and 2 of 17 (11%) with cleft lip only.

CONCLUSIONS

The incidence of anti-GERD pharmacologic therapy among infants with oral clefts (9%) is significantly higher than among the general pediatric population (<1%). Furthermore, palatal clefts impart a greater risk of GERD symptoms than clefts of the alveolus, lip, or nose. In order to minimize the long-term consequences of GERD, a standardized interdisciplinary clinical protocol is necessary for evaluating infants with oral clefts.

Esophageal pH and Combined Impedance-pH Monitoring in Children

Esophageal pH monitoring is considered the gold standard for the diagnosis of gastroesophageal reflux disease because of the normal ranges across the pediatric age range. However, this method can only detect acid reflux. Multichannel intraluminal impedance-pH (MII-pH) monitoring has recently been used for the detection of bolus reflux in infants and children. This method allows for the detection of liquid, gas or mixed reflux in addition to acid, weakly acidic or weakly alkaline reflux. MII-pH monitoring can record the direction of flow and the height of reflux, which are useful parameters to identify an association between symptoms and reflux. However, the technique is limited by its high cost and the lack of normative data of MII-pH in the pediatric population. Despite certain limitations, MII-pH monitoring will become more common and gradually replace pH monitoring in the future, because pH monitoring is part of MII-pH.

Detection of pepsin in mouth swab: correlation with clinical gastroesophageal reflux in preterm infants

OBJECTIVE

To study the relationship between pepsinogen/pepsin in a mouth swab and clinical gastroesophageal reflux (GER) in preterm infants.

METHODS

Preterm infants (birth weight ≤ 2000 g) on full enteral feeds were enrolled. Mouth swabs from cheek and below the tongue were collected one, two and three hours after feeding. An enzymatic assay with substrate fluorescein isothiocyanate-casein was used to detect pepsin A and C activities with further confirmation by western blot. Blinded investigators reviewed the infant's medical record to clinically diagnose GER.

RESULTS

A total of 101 premature infants were enrolled. Pepsinogen/pepsin was detected in 45/101 (44.5%) infants in at least one sample. A clinical diagnosis of GER was made in 36/101 (35.6%) infants. Mouth swabs were positive in 26/36 (72%) infants with clinical GER and only 19/65 (29%) infants without GER (p < 0.001). Similarly, the levels of pepsinogen/pepsin A and C were higher in the mouth swabs of infants with clinical GER.

CONCLUSION

The detection of pepsinogen/pepsin in a mouth swab correlates with clinical GER in premature infants.

Are contrast swallows a relevant investigation for paediatric stridor?

The contrast swallow has traditionally been used in the investigation of paediatric stridor with the aim of identifying pathology such as vascular rings and confirming the presence of gastro-oesophageal reflux. Currently, a laryngotracheobronchoscopy (LTB) is the gold standard investigation for stridor and frequently, a child is commenced on antireflux medications based on clinical history. We seek to identify whether a contrast swallow has a valuable and cost effective role in the investigation of paediatric stridor. This was a retrospective audit study. All the children who underwent a contrast swallow as part of the investigation for stridor were identified from 2008 to 2011. All requests were made by clinicians from the ENT department at Birmingham Children's Hospital. All patient demographics and radiological reports were reviewed. The final patient list was cross referenced with theatre records to identify those that underwent a LTB The cost of the contrast swallow was identified by the contracting department at Birmingham Children's Hospital. A total of 117 contrast swallows were requested during the study period. The age range was 1 week to 50 months with an average patient age of 6 months. 45/117 (38 %) of contrast swallows identified pathology. 33/45 (73 %) demonstrated reflux. Only 12/117 (10 %) of all cases suggested pathology other than reflux. A total of 51 patients underwent LTB. 22/51 (43 %) had a subsequent contrast swallow. Since the average cost per contrast swallow in the outpatient setting was £ 77, and only 9 cases demonstrated significant unexpected pathology, 108 children had a contrast swallow that did not significantly alter the management of their stridor. 9 cases were identified in which the contrast study results altered the management of the child. An estimated £ 8,000 were spent on investigations that made no impact on the subsequent management of the child. Contrast swallows requested for the investigation of paediatric stridor identified 33 cases of gastro-oesophageal reflux and 12 cases of alternative pathology. Among those children with radiological evidence of reflux, 70 % (23/33) had already been commenced on antireflux medication based on their clinical symptoms. Only 8 % of findings from a contrast swallow investigation resulted in a change to the management of the stridulous child. The authors suggest that it is more cost effective to reserve requests for a contrast swallow until the diagnostic LTB is performed. This strategy will not only reduce exposure to ionising radiation in a significant number of children, but also identifies airway pathology more effectively and ensures that contrast swallows are used as an appropriate adjunctive diagnostic investigation.

[The possibilities of reflux disease diagnosis by the ear, nose and throat specialist]

Reflux disease has gained in importance over the last decade since we know that many of the symptoms and diseases of the upper aerodigestive tract might be associated with reflux. However, a distinction needs to be made between extraesophageal reflux (EER) and gastroesophageal reflux disease (GERD). There are several techniques available for the diagnosis of EER. Furthermore, there are various pH monitoring devices to determine acid contamination of the larynx and the pharynx. In addition, flexible transnasal esophagoscopy is a practicable technique for the rapid examination of reflux, its cause as well as the diagnosis of reflux-induced mucosal changes in the esophagus. The present article describes the instruments used for the diagnosis of reflux against the background of our own experience and the international literature.

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.

Does Cholecystectomy Increase the Esophageal Alkaline Reflux? Evaluation by Impedance-pH Technique

Background/Aims

The aim of this study is to investigate the reflux patterns in patients with galbladder stone and the change of reflux patterns after cholecystectomy in such patients.

Methods

Fourteen patients with cholecystolithiasis and a control group including 10 healthy control subjects were enrolled in this prospective study. Demographical findings, reflux symptom score scale and 24-hour impedance pH values of the 14 cholecystolithiasis cases and the control group were evaluated. The impedance pH study was repeated 3 months after cholecystectomy.

Results

Age, gender, and BMI were not different between the two groups. Total and supine weakly alkaline reflux time (%) (1.0 vs 22.5, P = 0.028; 201.85 vs 9.65, P = 0.012), the longest episodes of total, upright and supine weakly alkaline reflux mediums (11 vs 2, P = 0.025; 8.5 vs 1.0, P = 0.035; 3 vs 0, P = 0.027), total and supine weakly alkaline reflux time in minutes (287.35 vs 75.10, P = 0.022; 62.5 vs 1.4, P = 0.017), the number of alkaline reflux episodes (162.5 vs 72.5, P = 0.022) were decreased with statistical significance. No statistically significant difference was found in the comparison of symptoms between the subjects in the control group and the patients with cholecystolithiasis, in preoperative, postoperative and postcholecystectomy status.

Conclusions

Significant reflux symptoms did not occur after cholecystectomy. Post cholecystectomy weakly alkaline reflux was decreased, but it was determined that acid reflux increased after cholecystectomy by impedance pH-metry in the study group.

Esophageal impedance in children: symptom-based results

OBJECTIVE

To correlate multiple intraluminal esophageal impedance recording with pH-monitoring with symptoms.

STUDY DESIGN

Symptoms occurring within a 2-minute window of a reflux were considered to be associated with reflux. Analyses were performed in 1- to 6-, 6- to 12-, and >12-months-old patients for crying, pain, cough, and vomiting.

RESULTS

A total of 70 of 225 tracings were discarded. Of 2172 symptoms, 1136 (52%) were reflux-associated (45% acid reflux [AR], 51% weakly AR, 3% alkaline reflux). The strongest reflux-symptom association was found for vomiting. Cough-reflux association was higher in infants than in older children. In older patients, symptom-reflux association was more with AR. Symptoms were associated with proximal reflux in 70% of patients. The symptom index and symptom association probability (SAP) were positive (>50% for symptom index and >95% for SAP) for all refluxes in 83% and 46% of patients and for AR in 49% and 47% of patients, respectively. In 1- to 6-month-old infants, symptom index and SAP were higher for weakly AR than for AR. For crying, SAP was independent of AR or weakly AR. For cough, SAP was positive in one-third of patients, predominantly with AR in 6- to 12-month-old infants and with weakly AR in the other infants.

CONCLUSION

Multiple intraluminal esophageal impedance recording with pH-monitoring doubles the probability of documenting an association between symptoms and reflux compared with pH monitoring. In young infants, symptoms are more frequently associated with weakly AR than with AR.

Pediatric specialists' beliefs about gastroesophageal reflux disease in premature infants

BACKGROUND

Wide variation exists in the treatment of suspected gastroesophageal reflux disease (GERD) in premature infants; it is unknown to what degree diagnosis and treatment are affected by the treating physician's medical specialty or interpretation of the medical literature.

METHODS

This study involved an online survey of board-certified neonatologists, pediatric pulmonologists, and pediatric gastroenterologists about their beliefs regarding the symptoms, diagnosis, and treatment of GERD in premature infants in the NICU on the basis of both clinical impression and interpretation of the literature.

RESULTS

A total of 1021 neonatologists, 232 pediatric pulmonologists, and 222 pediatric gastroenterologists participated in the study (47.5% response rate). There was disagreement among specialists in nearly all aspects of the survey. Pulmonologists were most likely to report that respiratory symptoms are caused by GERD (P < .001). Neonatologists were least likely to report that a therapeutic trial of pharmacologic agents would be useful for diagnosing GERD (P < .001) or that lansoprazole, ranitidine, or cimetidine are safe or effective (P < .001). No pharmacologic therapy had >50% of respondents supporting its effectiveness. There was moderate correlation between physician belief based on the medical literature and belief based on clinical impression (Spearman rank correlation: 0.47-0.75). For therapies supported by multiple meta-analyses in infants versus therapies with few infant trials, physicians rated the evidence for effectiveness similarly.

CONCLUSIONS

There is wide variation among pediatric specialists regarding beliefs about GERD in premature infants, as well as about the weight of evidence in the medical literature for this patient population. Physician beliefs do not seem to be driven by the degree of evidence in the neonatal literature. With no agreed-on standard of care in the setting of widespread use of antireflux medications, greater understanding is needed about the ways physicians form clinical impressions, access and process medical evidence, and apply it to patient care.

Reliability of oesophageal pH recording for the detection of gastro-oesophageal reflux

OBJECTIVE

Despite the new gold standard oesophageal impedance monitoring, pH monitoring is still used frequently for detection of gastro-oesophageal reflux (GOR). Besides drops in pH from above to below pH4, drops of > or =1 unit are also used as a marker for GOR. In this study the objective was to investigate the accuracy of drops in pH for detection of GOR, using impedance monitoring as the gold standard.

MATERIAL AND METHODS

Nineteen GORD patients (9 M, 55+/-11 years) underwent combined 24-h pH-impedance recording off acid-suppressive therapy. All drops in pH > or =0.5 pH units, with a duration > or =4 s, reaching the nadir pH within 5 s after onset were included. Reflux events detected with impedance monitoring were taken as the reference.

RESULTS

In total, 2221 drops in pH were found; 47% were acid (nadir pH <4), 47% weakly acidic (nadir pH between pH7 and 4) and 5% were superimposed (pH drop starting below pH4). The sensitivities of acid, weakly acidic and superimposed pH drops > or =1 were 91%, 28%, 24%, respectively, and the percentages of false-positive reflux episodes were 20, 56 and 54, respectively. Acid reflux with a cut-off > or =0.5 and < or =3.3 had a moderate-to-good sensitivity (94-70%) and low false-positive percentages (23-13%). In contrast, weakly acidic and superimposed reflux showed greater false-positive than true-positive percentages for all cut-off values.

CONCLUSIONS

Compared to impedance monitoring, detection of reflux with pH monitoring is clearly inferior. When drops in pH > or =1 are used irrespective of nadir pH as an indicator of reflux episodes, the number of reflux episodes is overestimated. Decreases from above to below 4 with cut-offs between > or =0.5 and < or =3.3 are the most indicative of true reflux episodes.

Apnea, bradycardia and desaturation in preterm infants before and after feeding

OBJECTIVE

A common clinical impression is that both gastroesophageal reflux (GER) and cardiorespiratory events increase after feeding in preterm infants. We aimed to measure objectively the effects of feeding on GER, apnea, bradycardia and desaturations.

STUDY DESIGN

We conducted a retrospective review of premature infants with a gestational age of 23 to 37 weeks at birth and a post-conceptional age of 34 to 48 weeks, who were referred for multichannel intraluminal impedance (MII), pH probe and 12-h apnea evaluation. Cardiorespiratory and GER event rates during pre- and post-feeding intervals were compared.

RESULT

Thirty-six infants met the inclusion criteria. More GER events occurred after a feed than before (P=0.012). After feeds, reflux was less acidic and higher in the esophagus (P<0.05). In contrast, the rates of apnea, bradycardia and desaturations were not altered by infant feeding. Apnea of >5 s occurred at a median frequency of 0 (range 0 to 3) events per hour before a feed and 0 (0 to 2) events per hour after a feed (P=0.61).

CONCLUSION

The frequency, height and pH of GER are significantly altered by feedings in preterm infants. However, the common clinical impression that apnea, bradycardia and desaturations are more prevalent after feeding is not supported.

Addition of pH-impedance monitoring to standard pH monitoring increases the yield of symptom association analysis in infants and children with gastroesophageal reflux

OBJECTIVE

To assess the additional yield of combined multichannel intraluminal pH-impedance (pH-MII) monitoring compared with standard pH monitoring on gastroesophageal reflux (GER) symptom associations in infants and children.

STUDY DESIGN

In 80 patients, 24-hour ambulatory pH-MII monitoring was performed. Tracings were analyzed with established pH-MII criteria. Symptoms of regurgitation and belching were excluded from analysis, because these were considered to be a direct consequence of GER. Standard GER-symptom correlation indices were calculated with: 1) standard pH monitoring; 2) MII detection of liquid and mixed bolus GER; 3) MII detection of all bolus GER (liquid, mixed, and gas); 4) pH-MII detection of all GER, including pH-only GER.

RESULTS

Fifty patients (21 children) were included. MII detection of all bolus GER yielded a significantly greater number of patients who were symptom-positive, 36 (72%) compared with 25 (50%) with standard pH-monitoring (P = .04). A positive symptom association was observed in 8 of 10 (80%) patients with pathological esophageal acid exposure and 28 of 40 (70%) patients with negative pH-findings.

CONCLUSIONS

A high proportion of patients with normal esophageal acid exposure had a positive symptom association on pH-MII monitoring. Including all MII-detected bolus GER and excluding pH-only GER for analysis optimizes the yield of GER-symptom associations in infants and children.

Neonatal apnea: what's new?

Apnea of prematurity (AOP) remains a major clinical problem in present day neonatology that warrants frequent evaluations and imposes challenges in therapeutic strategies. Although the pathogenesis of AOP is poorly understood, it is probably a manifestation of physiologic immaturity of breathing control rather than a pathologic disorder. Immature breathing responses to hypoxia, hypercapnia and exaggerated inhibitory pulmonary reflexes in preterm infants might also contribute to the occurrence or severity of AOP. Recent data suggest a role for genetic predisposition. Although typically resolve with maturation, the role of bradycardia and desaturation episodes associated with AOP in the development of sleep disorder breathing and neurodevelopmental delay needs further clarification. Pharmacological treatment with methylxanthines and CPAP remain the mainstay for treatment of AOP. However, recent studies have implicated central inhibitory neuromodulators including prostaglandins, GABA and adenosine in its pathogenesis, the fact that might provide future specific targets for treatment. This review will summarize new insights involving these issues as well as others involving the pathogenesis, treatment strategies and consequences of apnea in premature infants.

Infant apnea and gastroesophageal reflux: a critical review and framework for further investigation

Gastroesophageal reflux and apnea of prematurity are both common occurrences in premature infants. However, a causal relationship between the two remains controversial. Strong physiologic evidence indicates that a variety of protective reflex responses may elicit laryngeal adduction and apnea. Although a potential link between gastroesophageal reflux and apnea may exist through this pathway, clinical studies can be cited to either support or refute such a link in premature infants. The majority of gastroesophageal reflux episodes do not appear to be related to apnea. In a specific subset of events, a causal relationship may exist. Whether this is related to the character of the reflux episode or to a predisposition in a subpopulation of infants is unclear. This review presents the evidence for and against an association between gastroesophageal reflux and apnea, discusses techniques used in their evaluation, and identifies approaches for future investigation.

Gastro-oesophageal reflux disease: oesophageal impedance versus pH monitoring

Gastro-oesophageal reflux occurs frequently during the first months of life. Infants receive frequent milk feeds, and because milk is a potent buffer of gastric acidity, oesophageal impedance should detect more reflux than pH recording. Indeed, impedance has the advantage over pH monitoring of being independent of pH, and as a consequence, of being better adapted to measure reflux during postprandial periods when reflux is buffered and to detect symptoms associated with non-acid or weakly acid reflux episodes. Numerous episodes are detected by one of these techniques (pH monitoring or impedance) in children. Most studies using the impedance technique consider very small numbers of patients, and there are few reports linking data from diagnostic impedance procedures to clinical outcome in symptomatic patients. Data suggesting that impedance does offer a clear-cut benefit in paediatric clinical practice are missing. The high cost of the material and the investment in time necessary for interpretation of the recording, remains a handicap. It is mandatory, despite ethical difficulties, to obtain normal ranges for intraluminal impedance monitoring.

CONCLUSION

As pH monitoring is part of impedance technology, it is likely that the latter will replace pH monitoring despite the current lack of scientific evidence demonstrating a relation between symptoms, oesophageal damage or response to reflux treatment and impedance-pH results.