Characterisation of relaxation of the lower oesophageal sphincter in healthy premature infants

Gastroesophageal reflux disease in children: What’s new right now?

Gastroesophageal reflux (GER) in children is very common and refers to the involuntary passage of gastric contents into the esophagus. This is often physiological and managed conservatively. In contrast, GER disease (GERD) is a less common pathologic process causing troublesome symptoms, which may need medical management. Apart from abnormal transient relaxations of the lower esophageal sphincter, other factors that play a role in the pathogenesis of GERD include defects in esophageal mucosal defense, impaired esophageal and gastric motility and clearance, as well as anatomical defects of the lower esophageal reflux barrier such as hiatal hernia. The clinical manifestations of GERD in young children are varied and nonspecific prompting the necessity for careful diagnostic evaluation. Management should be targeted to the underlying aetiopathogenesis and to limit complications of GERD. The following review focuses on up-to-date information regarding of the pathogenesis, diagnostic evaluation and management of GERD in children.

Review of paediatric gastrointestinal physiology relevant to the absorption of orally administered medicines

Despite much progress in regulations to improve paediatric drug development, there remains a significant need to develop better medications for children. For the design of oral dosage forms, a detailed understanding of the specific gastrointestinal (GI) conditions in children of different age categories and how they differ from GI conditions in adults is essential. Several review articles have been published addressing the ontogeny of GI characteristics, including luminal conditions in the GI tract of children. However, the data reported in most of these reviews are of limited quality because (1) information was cited from very old publications and sometimes low quality sources, (2) data gaps in the original data were filled with textbook knowledge, (3) data obtained on healthy and sick children were mixed, (4) average data obtained on groups of patients were mixed with data obtained on individual patients, and (5) results obtained using investigative techniques that may have altered the outcome of the respective studies were considered. Consequently, many of these reviews draw conclusions that may be incorrect. The aim of the present review was to provide a comprehensive and updated overview of the available original data on the ontogeny of GI luminal conditions relevant to oral drug absorption in the paediatric population. To this end, the PubMed and Web of Science metadatabases were searched for appropriate studies that examined age-related conditions in the oral cavity, esophagus, stomach, small intestine, and colon. Maturation was observed for several GI parameters, and corresponding data sets were identified for each paediatric age group. However, it also became clear that the ontogeny of several GI traits in the paediatric population is not yet known. The review article provides a robust and valuable data set for the development of paediatric in vitro and in silico biopharmaceutical tools to support the development of age-appropriate dosage forms. In addition, it provides important information on existing data gaps and should provide impetus for further systematic and well-designed in vivo studies on GI physiology in children of specific age groups in order to close existing knowledge gaps and to sustainably improve oral drug therapy in children.

Pathophysiology of Pediatric Gastroesophageal Reflux Disease: Similarities and Differences With Adults

Gastroesophageal reflux (GOR) is defined as "the passage of gastric contents into the esophagus with or without regurgitation and vomiting" and gastroesophageal reflux disease (GORD) is defined "when GOR leads to troublesome symptoms affecting the daily functioning and/or complications." This definition was first developed in 2006 by the Montreal consensus group (1) and later on adopted by pediatric gastroenterology societies such as ESPGHAN and NASPGHAN in 2009 (2). The definition of gastroesophageal reflux reveals little about its pathophysiology and is focused on symptomatology. In this way, it acts as an umbrella term for the multifactorial causes of the disease and the various phenotypes encountered; from functional heartburn to hypersensitive esophagus and nonerosive reflux disease, to erosive esophagitis and Barrett's esophagus. This article is devoted to the pathophysiology of pediatric GORD in comparison to adult GORD and is divided in 2 parts. In the first part, we will systematically describe the different mechanisms for the generation and clearance of reflux events, while on the second part we will discuss the mechanisms involved in symptoms generation. Finally, we will discuss the similarities and differences between pediatric and adult GORD.

Diagnostic utility of impedance-pH monitoring in infants of diabetic mothers with oral feeding difficulties

OBJECTIVE

To determine the diagnostic utility of impedance-pH monitoring in infants of diabetic mothers (IDM) with oral feeding difficulties.

STUDY DESIGN

Retrospective review of a consecutive sample of 50 IDM who had impedance-pH monitoring for objective gastroesophageal reflux disease (GERD) diagnosis. Acid reflux index (ARI) ≥ 7 was considered pathological (ARI+).

RESULTS

Impedance-pH monitoring was performed at 42.1-week postmenstrual age. Twenty infants (40%) with ARI+ compared to 30 with ARI < 7 (ARI-). ARI+ had lower weight at study vs. ARI- (p < 0.05). ARI+ had significantly higher reflux parameters but had similar symptom burden and symptom-association scores vs. ARI-. All ARI+ received proton-pump inhibitors (PPI) vs. 7 (23.3%) in ARI- (p < 0.05), but oral feeding outcomes, gastrostomy rate, growth, and hospital length of stay were similar in both groups.

CONCLUSIONS

The diagnostic yield of impedance-pH monitoring in IDM is about 40%. However, GERD diagnosis or treatment with PPI did not modify short-term clinical outcomes.

Verifying the placement and length of feeding tubes in canine and feline neonates

Background

Tube feeding is a common procedure in neonatology. In humans, tube misplacement reportedly occurs in up to 59% of all cases and may lead to perforation in 1.1% of preterm intubated neonates. While numerous studies on optimal tube placement have been performed in human neonates, current recommendations on tube feeding in canine and feline neonatology are based, at best, on studies performed in adult animals. Herein, we aimed to test ultrasonography as a tool to verify tube placement in puppies and kittens and to compare different anatomical predictive markers used in human, canine and feline neonates.

Results

The predictive tube length when held bent between the last rib and the mouth may induce trauma compared to when held straight. A strong positive linear correlation was observed between birthweight and gastric cardia localization. Ultrasonography findings were similar to coeliotomy findings. Stomach volume was less than 2 mL per 100 g in the less-than-one-day-old studied puppies (n = 25) and kittens (n = 28).

Conclusions

A weight-based equation was calculated to help predict appropriate tube placement. Ultrasonography can be used to control gastric tube placement, and neonates less than one-day-old have a smaller stomach capacity. Further studies are required to evaluate whether more-than-one-day-old puppies follow the same linear correlation with their weight. Further in vivo studies are warranted to determine the gold standard procedure for tube feeding in neonatal puppies and kittens.

The influence of Intrapulmonary percussive ventilation on gastroesophageal reflux in infants under the age of 1 year

BACKGROUND

Intrapulmonary percussive ventilation (IPV) is an airway clearance technique used at any age to facilitate the removal of secretions from the respiratory tract. The effect of IPV on gastroesophageal reflux(GER) is not well documented. This study aimed to determine the influence of IPV on GER in infants.

METHODS

During a 24-hour multichannel intraluminal impedance-pH monitoring (MII-pH), infants in the intervention group received a20 minutes session of IPV in upright position, 2 hours postprandial. The control group received no intervention and was placed in the same position for 20 minutes, 2 hours postprandial. The number of reflux episodes (REs) during IPV as compared to the number of REs in the control group during the 20 minutes period.

RESULTS

Fifty infants were included in each group;21 infants in the IPV group and 14 infants in the control group were diagnosed with abnormal MII-pH (P = .142). During IPV, the number of REs was significantly lower than in the control group (P < .001). Also in the subgroups with abnormal or normal MII-pH, a significantly lower number of REs during IPV was found (P = .011, P = .011 respectively).

CONCLUSION

IPV decreases the number of REs in infants independent of the results of MII-pH.

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.

Gastroesophageal Reflux Disease in the Neonatal Intensive Care Unit Neonate: Controversies, Current Understanding, and Future Directions

Gastroesophageal reflux (GER) is considered physiologic and is a normal process; whereas, when aerodigestive consequences are associated, it is often interpreted as GER disease (GERD). However, the distinction between them remains a challenge in infants in the NICU. Reflux-type of symptoms are heterogeneous, and often managed with changes in diet, feeding methods, and acid-suppressive therapy; all these empiric therapies lack objectivity; hence, practice variation is universal. We clarify the current controversies, explain the potential role of GERD in causing symptoms and complications, and highlight current advances. The evidence basis for the diagnostic strategies is discussed.

The enigma of gastroesophageal reflux disease among convalescing infants in the NICU: It is time to rethink

Gastroesophageal reflux (GER) can be a normal physiological process, or can be bothersome, when aerodigestive consequences are associated; the latter is often interpreted as GER disease (GERD). However, the distinction between these two entities remains an enigma among infants surviving after neonatal intensive care (NICU) care. Symptoms related to GERD are heterogeneous, and are often managed with changes in diet, feeding methods, and acid suppressive therapy. However, none of these approaches have been well-tested in neonates; hence practice variation is very high world-wide. In this paper, we explain the variation in diagnosis, pathophysiology of the clinical presentation, and highlight approaches to diagnosis and management.

Relationship Between Tongue Pressure and Pharyngeal Function Assessed Using High-Resolution Manometry in Older Dysphagia Patients with Sarcopenia: A Pilot Study

Tongue pressure is often used to evaluate swallowing muscle strength in dysphagia patients with sarcopenia. However, the amount of tongue pressure that reflects pharyngeal swallowing function is unclear. The aims of this descriptive study were (1) to assess the association between tongue pressure and swallowing function using high-resolution manometry (HRM), (2) to evaluate whether manometric parameters were related to maximum tongue pressure (MTP) and other sarcopenia-related factors, and (3) to evaluate the manometric characteristics of pharyngeal swallowing in sarcopenic dysphagia. Sixteen patients with dysphagia (13 men; mean age 85.0 ± 6.6) who were diagnosed with sarcopenia and sixteen healthy subjects (10 men; mean age 33.6 ± 7.2) were included. Evaluation of HRM parameters including velopharyngeal contractile integral (VPCI), mesohypopharyngeal contractile integral (MHPCI), upper esophageal sphincter (UES) relaxation duration, and UES nadir pressure was performed. HRM parameters of patients were compared with MTP, sarcopenia factors, and manometric parameters of healthy subjects. The VPCI showed no statistically significant differences between patient and healthy groups. In the patient group, the MHPCI was significantly lower (126.1 ± 76.6 vs 193.2 ± 34.1 mmHg cm s; p = 0.003), UES nadir pressure was significantly higher (10.5 ± 27.5 vs - 11.2 ± 6.7 mmHg; p < 0.001), and UES relaxation duration (318.0 ± 152.4 vs 520.6 ± 60.0 ms; p = 0.007) was significantly shorter than those in the healthy group. HRM parameters were not significantly correlated with MTP and sarcopenia factors. Older dysphagia patients with sarcopenia had weaker pharyngeal contractility and UES dysfunction. Manometric evaluation of pharyngeal function may not be significantly associated with MTP and sarcopenia-related factors. Further study is needed to clinically apply tongue pressure for evaluating sarcopenic dysphagia.

Assessment and Management of Gastroesophageal Reflux in The Newborn

Gastroesophageal reflux is the involuntary retrograde passage of gastric contents into the esophagus with or without regurgitation and is considered a normal physiologic process, occurring daily in greater than one-third of all infants. Gastroesophageal reflux disease (GERD) is pathologic reflux associated with poor weight gain, irritability, dysphagia and often requires evaluation and treatment. No gold-standard testing for GERD exists. Measurements made by pH probe or multichannel intraesophageal impedance may provide insight into the quantity and character of reflux. Those events do not correlate well with clinical symptoms. Most cases of GERD can be treated conservatively with alterations in the infant's environment and/or feeding pattern. Proton pump inhibitors remain the mainstay for pharmacotherapy of GERD, although these have been associated with increased rates of infection, especially in the preterm population. Neonatal GERD remains a difficult entity to define and manage, and additional studies to aid in the clinical diagnosis and management are needed. [Pediatr Ann. 2020;49(2):e77-e81.].

Maturation of Esophageal Motility and Esophagogastric Junction in Preterm Infants

BACKGROUND

Preterm infants commonly present with oral feeding problems. The role of maturation of esophageal bolus transport mechanisms herein remains unclear.

OBJECTIVES

To characterize esophageal motility and function of esophagogastric junction (EGJ) during deglutitive swallowing in healthy preterm infants and to describe maturational changes.

METHODS

Four consecutive high-resolution manometry studies with impedance studies were performed weekly to investigate esophageal motility and EGJ function. Esophageal pressure topography and pressure-impedance metrics were derived. Mixed models with repeated measures were used for statistical analysis.

RESULTS

We analyzed 137 nutritive swallows from 36 motility studies in 10 preterm infants. The mean gestational age was 30.17 ± 0.94 weeks; the mean postmenstrual age at time point 1 and 4 was 34.42 ± 0.86 and 37.45 ± 1.16 weeks, respectively. Esophageal peristaltic wave patterns in response to nutritive swallows were observed in all patients. At later time points, esophageal body peristalsis became more rapid, evidenced by a faster distal contractile velocity and shorter distal latency (p = 0.002 and p < 0.0001, respectively). In addition, 4-s integrated relaxation pressures increased and distal contractile integral decreased at later time points (p = 0.003 and p = 0.021, respectively). Bolus clearance also improved at later age (p = 0.008).

CONCLUSIONS

Preterm infants demonstrate peristaltic esophageal motility following nutritive swallows. However, alterations in esophageal bolus transport in relation to peristalsis are demonstrated. Peristaltic progression becomes more rapid, while deglutitive relaxation pressures increase with increasing age. These maturational changes may suggest further development of the enteric nervous system after birth in former preterm neonates.

Characterization of Esophageal Motility in Infants With Congenital Diaphragmatic Hernia Using High-resolution Manometry

OBJECTIVES

The aim of the study was to characterize esophageal motility and esophagogastric junction (EGJ) function in infants who underwent repair of an isolated congenital diaphragmatic hernia (iCDH).

METHODS

High-resolution manometry with impedance was used to investigate esophageal motility and EGJ function after diaphragmatic repair in 12 infants with iCDH (11 left-sided; 9 patch repair). They had esophageal motility studies during neonatal admission (n = 12), at 6 months (n = 10) and at 12 months of life (n = 7). Swallows were analyzed using conventional esophageal pressure topography and pressure flow analysis and were compared with 11 healthy preterm born infants at near-term age.

RESULTS

Esophageal peristaltic motor patterns in patients with iCDH were comparable to controls. EGJ end-expiratory pressure was higher in patients with patch repair compared with controls (P = 0.050) and those without patch (P = 0.009). The difference between inspiratory and expiratory pressures at the EGJ was lower in patients with iCDH with patch (P = 0.045) compared to patients without. Patients with iCDH with patch showed increased Pressure Flow Index, resistance of bolus flow at the EGJ, compared with controls (P = 0.043).

CONCLUSIONS

Normal esophageal wave patterns are present in the investigated patients with iCDH. EGJ end-expiratory pressure seems lower in patients with iCDH without patch suggesting a decreased EGJ barrier function hence increased vulnerability to gastroesophageal reflux. Patch repair appears to increase end-expiratory pressure at the EGJ above that of controls suggesting that patch surgery tightens the EGJ, thereby increasing flow resistance. This is in line with the increased Pressure Flow Index. In infants with a patch, the inspiration-expiration pressure difference is lower, reflecting diminished activity of the crural diaphragm.

Gastroesophageal Reflux Disease in the Neonatal Intensive Care Unit Infant: Who Needs to Be Treated and What Approach Is Beneficial?

Gastroesophageal reflux (GER) and GER disease (GERD) pertaining to infants in the neonatal intensive care unit (NICU) are reviewed, based on research in this specific population. The developmental biology of the gastroesophageal junction, physiology of GER, and pathophysiology of GERD in this setting are summarized, and risk factors for GER and GERD identified. The epidemiology, economic burden, and controversies surrounding GERD in NICU infants are addressed, and an approach to GER and GERD in these patients formulated. Recent advancements in individual assessment of GER and GERD in the NICU infant are examined, and evidence-based guidelines for their adoption provided.

Motility disorders in infants

Gastrointestinal motility disorders are common in the pediatric population and may affect the entire gastrointestinal tract and can vary from mild to severe conditions. They may clinically manifest as gastro-esophageal reflux symptoms, feeding difficulties and failure to thrive, constipation and diarrhea amongst others. This review first highlights the embryologic development of the gastrointestinal tract, after which the prenatal and neonatal development of gastrointestinal motility is discussed. Normal motility patterns as seen in (preterm) infants are described as a background for the discussion of the most common congenital and acquired motility disorders in infancy. This review specifically focuses on the role of preterm birth on the development of these disorders.

Quantitative Analysis of Swallowing Function Between Dysphagia Patients and Healthy Subjects Using High-Resolution Manometry

Objective

To compare swallowing function between healthy subjects and patients with pharyngeal dysphagia using high resolution manometry (HRM) and to evaluate the usefulness of HRM for detecting pharyngeal dysphagia.

Methods

Seventy-five patients with dysphagia and 28 healthy subjects were included in this study. Diagnosis of dysphagia was confirmed by a videofluoroscopy. HRM was performed to measure pressure and timing information at the velopharynx (VP), tongue base (TB), and upper esophageal sphincter (UES). HRM parameters were compared between dysphagia and healthy groups. Optimal threshold values of significant HRM parameters for dysphagia were determined.

Results

VP maximal pressure, TB maximal pressure, UES relaxation duration, and UES resting pressure were lower in the dysphagia group than those in healthy group. UES minimal pressure was higher in dysphagia group than in the healthy group. Receiver operating characteristic (ROC) analyses were conducted to validate optimal threshold values for significant HRM parameters to identify patients with pharyngeal dysphagia. With maximal VP pressure at a threshold value of 144.0 mmHg, dysphagia was identified with 96.4% sensitivity and 74.7% specificity. With maximal TB pressure at a threshold value of 158.0 mmHg, dysphagia was identified with 96.4% sensitivity and 77.3% specificity. At a threshold value of 2.0 mmHg for UES minimal pressure, dysphagia was diagnosed at 74.7% sensitivity and 60.7% specificity. Lastly, UES relaxation duration of <0.58 seconds had 85.7% sensitivity and 65.3% specificity, and UES resting pressure of <75.0 mmHg had 89.3% sensitivity and 90.7% specificity for identifying dysphagia.

Conclusion

We present evidence that HRM could be a useful evaluation tool for detecting pharyngeal dysphagia.

Ability of High-Resolution Manometry to Determine Feeding Method and to Predict Aspiration Pneumonia in Patients With Dysphagia

OBJECTIVES

The introduction of high-resolution manometry (HRM) offered an improved method to objectively analyze the status of pharynx and esophagus. At present, HRM for patients with oropharyngeal dysphagia has been poorly studied. We aimed to determine feeding method and predict the development of aspiration pneumonia in patients with oropharyngeal dysphagia using HRM.

METHODS

We recruited 120 patients with dysphagia who underwent both HRM and videofluoroscopic swallow study. HRM was used to estimate pressure events from velopharynx (VP) to upper esophageal sphincter (UES). Feeding methods were determined to non-oral or oral feeding according to dysphagia severity. We prospectively followed patients to assess the development of aspiration pneumonia.

RESULTS

VP maximal pressure and UES relaxation duration were independently associated with non-oral feeding. Non-oral feeding was determined based on optimal cutoff value of 105.0 mm Hg for VP maximal pressure (95.0% sensitivity and 70.0% specificity) and 0.45 s for UES relaxation duration (76.3% sensitivity and 57.5% specificity), respectively. During a mean follow-up of 18.8 months, 15.8% of patients developed aspiration pneumonia. On multivariate Cox regression analysis, VP maximal pressure (P<0.01) and UES relaxation duration (P<0.05) independently predicted the development of aspiration pneumonia. Cumulative incidence of aspiration pneumonia was significantly increased in patients with readings below optimal cutoff values for VP maximal pressure (P<0.01) and UES relaxation duration (P<0.01), individually.

CONCLUSIONS

We first established the optimal thresholds for HRM parameters to determine feeding method and predict the development of aspiration pneumonia in patients with oropharyngeal dysphagia.

Failed Deglutitive Upper Esophageal Sphincter Relaxation Is a Risk Factor for Aspiration in Stroke Patients with Oropharyngeal Dysphagia

Background/Aims

We attempted to examine the relationship between abnormal findings on high-resolution manometry (HRM) and videofluoroscopic swallowing study (VFSS) of the pharynx and upper esophageal sphincter (UES), and to identify the risk factors for aspiration.

Methods

We performed VFSS and HRM on the same day in 36 ischemic stroke patients (mean age, 67.5 years) with dysphagia. Pressure (basal, median intra bolus, and nadir), relaxation time interval of the UES, and mesopharyngeal and hypopharyngeal contractility (as a contractile integral) were examined using HRM. The parameters of VFSS were vallecular residue, pyriform sinus residue, vallecular overflow, penetration, and aspiration. The association between the parameters of VFSS and HRM was analyzed by the Student’s t test.

Results

Three (8.3%) and 4 (11.1%) stroke patients with dysphagia had pyriform sinus residue and vallecular sinus residue, respectively, and 5 (13.8%) patients showed aspiration. Mesopharyngeal and hypopharyngeal contractile integrals in patients with residue in the pyriform sinus were significantly lower than those in patients without residue in the pyriform sinus (P < 0.05). Relaxation time intervals in patients with aspiration were significantly shorter than those in patients without aspiration (P < 0.05), and multivariate regression analysis revealed a shorter relaxation time interval as the main risk factor for aspiration (OR, 0.03; 95% CI, 0.01–0.65; P < 0.05).

Conclusions

Manometric measurements of the pharynx and UES were well correlated with abnormal findings in the VFSS, and a shorter relaxation time interval of the UES during deglutition is an important parameter for the development of aspiration.

Upper gastrointestinal motility: prenatal development and problems in infancy

Deglutition, or swallowing, refers to the process of propulsion of a food bolus from the mouth into the stomach and involves the highly coordinated interplay of swallowing and breathing. At 34 weeks gestational age most neonates are capable of successful oral feeding if born at this time; however, the maturation of respiration is still in progress at this stage. Infants can experience congenital and developmental pharyngeal and/or gastrointestinal motility disorders, which might manifest clinically as gastro-oesophageal reflux (GER) symptoms, feeding difficulties and/or refusal, choking episodes and airway changes secondary to micro or overt aspiration. These problems might lead to impaired nutritional intake and failure to thrive. These gastrointestinal motility disorders are mostly classified according to the phase of swallowing in which they occur, that is, the oral preparatory, oral, pharyngeal and oesophageal phases. GER is a common phenomenon in infancy and is referred to as GERD when it causes troublesome complications. GER is predominantly caused by transient relaxation of the lower oesophageal sphincter. In oesophageal atresia, oesophageal motility disorders develop in almost all patients after surgery; however, a congenital origin of disordered motility has also been proposed. This Review highlights the prenatal development of upper gastrointestinal motility and describes the most common motility disorders that occur in early infancy.

Magnetic resonance imaging of the normal fetal esophagus

OBJECTIVES

To establish the appearance on magnetic resonance imaging (MRI) of the normal fetal esophagus and to provide biometric data from 20 to 39 gestational weeks.

METHODS

In this retrospective study of 250 fetal MRI examinations (20-39 gestational weeks) the visibility of the upper (E1, cervical to tracheal bifurcation) and lower (E2, tracheal bifurcation to diaphragm) esophageal segments was assessed separately in each of three section planes. Segments were scored as being visible or not, and whether they were fluid-filled was noted. Maximum esophageal diameters were recorded. To study the age dependency of esophageal visualization, fetuses were divided into three age groups: 20-25, 26-31 and 32-39 weeks. In 19 cases, there were dynamic studies and these were analyzed for the duration of fluid-filling.

RESULTS

Segment E1 was visualized only when it was fluid-filled and it was visible in 16.8% of axial, 4% of frontal and 22.4% of sagittal acquisitions. Segment E2 could also be detected in the unfilled state, when it appeared solid; it was seen in 96.4% of axial, 74% of frontal and 39.6% of sagittal acquisitions, being fluid-filled in 62.7-88.9% of these. Depending on the amount of fluid-filling and the gestational age, E2 segments had a variable appearance. Dynamic scans showed E1 segments to be fluid-filled for periods of 0.5-1.5 s and E2 segments for periods of 3-35 s. Both the frequency of visualization and the maximum diameter increased linearly with gestational age.

CONCLUSION

Visualization of the fetal esophagus by MRI depends on section plane, segment and gestational age, with considerable differences between the two segments: while E1 requires fluid-filling related to fetal swallowing, the E2 portion can usually be demonstrated independent of fluid-filling, as a consequence of its topographical relationships. The frequently fluid-filled state of E2 may reflect the immature nature of esophageal neuromuscular activity, and the lack of an anti-reflux mechanism due to the short length of the abdominal esophagus.

Diagnosis of gastroesophageal reflux disease in infants

Gastroesophageal reflux is commonly encountered in the infant population. Most children will outgrow their reflux but some develop pervasive disease and require medical or surgical treatment. Many tools exist for use in the workup of pediatric gastroesophageal reflux disease; however, the most effective method of diagnosis is not clear. Delineating which patients will benefit from more definitive therapy is a remarkable challenge in this group, often borrowing tools and principles from the adult patient population. Therefore, we reviewed the available literature to critically evaluate the merits and limitations of the current diagnostic modalities available for the evaluation of infantile gastroesophageal reflux.

Lower esophageal sphincter relaxation reflex kinetics: effects of peristaltic reflexes and maturation in human premature neonates

We defined the sensory-motor characteristics of the lower esophageal sphincter relaxation (LESR) (stimulus threshold volume, response onset, and relaxation period, relaxation magnitude, nadir) during maturation in human neonates. We hypothesized that LESR kinetics differs during maturation and with peristaltic reflex type. Basal and adaptive esophageal motility testing was performed (N = 20 premature neonates) at 34.7 and 39.1 wk (time 1 and time 2). Effects of midesophageal provocation with graded stimuli (N = 1,267 stimuli, air and liquids) on LESR kinetics during esophagodeglutition response (EDR) and secondary peristalsis (SP) were analyzed by mixed models. Frequency of LESR with basal primary peristalsis were different during maturation (P = 0.03). During adaptive responses with maturation, 1) the frequencies of peristaltic reflexes and LESR were similar; 2) liquid stimuli resulted in a shorter LESR response latency and LESR nadir and greater LESR magnitude (all P < 0.05); 3) media differences were noted with LESR response latency (air vs. liquids, P < 0.02); and 4) infusion flow rate-LESR were different (P < 0.01 for air and liquids). Mechanistically, 1) frequency of LESR was greater during peristaltic reflexes at both times (vs. none, P < 0.0001); 2) LESR response latency, duration, and time to complete LESR were longer with EDR (all P < 0.05, vs. SP at time 2); and 3) graded stimulus volume LESR were different for air and liquids (P < 0.01). In conclusion, sensory-motor characteristics of LESR depend on the mechanosensitive properties of the stimulus (media, volume, flow), type of peristaltic reflex, and postnatal maturation. Maturation modulates an increased recruitment of inhibitory pathways that favor LESR.

Role of the multichannel intraluminal impedance technique in infants and children

Recently, multichannel intraluminal impedance (MII) was added to the repertoire of tests available to study esophageal (patho)physiology in children. MII has since been used in 2 major areas. First, it has been used as a diagnostic test for gastroesophageal reflux disease (GERD). The main advantage over traditional pH monitoring is its ability to detect both acid and nonacid gastroesophageal reflux (GER) and to discern between liquid and gas GER.Although feasible with multiple pH sensors, the MII technique routinely detects the proximal extent of a GER episode. When a pH sensor is added to the MII-catheter, important information about the acidity of a GER event can be gathered.The second area in which the role of MII has been investigated is that of esophageal function testing. Manometry classically reveals information about esophageal pressure patterns and sphincter function, but does not inform us about bolus flow. MII not only detects the presence of esophageal flow but also adds information on the direction of flow, duration of bolus presence, completeness of bolus clearance, and composition of a bolus.The combination of MII with manometry enables determination of the relationship between esophageal pressures and flow and, therefore, enhances evaluation of esophageal function in terms of assessment of mechanisms of esophageal volume clearance. In addition, this technique will improve our understanding of (patho)physiological mechanisms in pediatric GERD and other esophageal motility disorders.

Development of esophageal peristalsis in preterm and term neonates

BACKGROUND & AIMS

High-resolution manometry demonstrates a chain of 3 sequential pressure segments that represent esophageal peristalsis in children and adults. We performed high-resolution manometry in preterm and term neonates to determine the ontogenesis of esophageal motility with regard to this segmental architecture.

METHODS

Sixteen preterm (gestational age 32.9 +/- 2.6 weeks at examination) and 14 term neonates (38.9 +/- 1.6 weeks) underwent manometry with a 9-lumen perfused catheter having recording side holes spaced at 1-cm intervals. Pressure responses to swallows were evaluated for the presence of peristaltic segments on isobaric contour maps by an investigator who was blinded to gestational age.

RESULTS

The second segment was well developed in > or =50% of swallows in all preterm and term neonates. In contrast, the first segment was present in > or =50% of swallows in only 2 preterm neonates (12.5%) and 8 term neonates (57.1%; P < .05 for each compared with second segment) with identical findings for the third segment (12.5% preterm and 57.1% term neonates; P < .05 for each). Completed peristalses with intact segmental contraction sequences throughout the esophageal body were present in 26% +/- 6% of swallows in preterm neonates vs 55% +/- 9% in term neonates (P = .01).

CONCLUSIONS

The second pressure segment in the midesophagus (proximal smooth-muscle region) is well developed before term. Presence of other segments significantly improves at term, but peristalsis remains incomplete in nearly half of swallows. Control mechanisms for both striated- and smooth-muscle esophageal regions are incompletely developed in neonates, the outcome of which could participate in infant reflux disease.

Effect of omeprazole on acid gastroesophageal reflux and gastric acidity in preterm infants with pathological acid reflux

INTRODUCTION

Proton pump inhibitor (PPI) therapy is increasingly being used to treat premature infants with gastroesophageal reflux disease (GERD); however, the efficacy of PPI on acid production in this population has yet to be assessed in this patient group. The aim of this study was to determine the effect of 0.7 mg/kg/d omeprazole on gastric acidity and acid gastroesophageal reflux in preterm infants with reflux symptoms and pathological acid reflux on 24-h pH probe.

METHODS

A randomized, double blind, placebo-controlled, crossover design trial of omeprazole therapy was performed in 10 preterm infants (34-40 weeks postmenstrual age). Infants were given omeprazole for 7 d and then placebo for 7 d in randomized order. Twenty-four-hour esophageal and gastric pH monitoring was performed on days 7 and 14 of the trial.

RESULTS

Compared to placebo, omeprazole therapy significantly reduced gastric acidity (%time pH <4, 54% vs 14%, P < 0.0005), esophageal acid exposure (%time pH <4, 19% vs 5%, P < 0.01) and number of acid GER episodes (119 vs 60 episodes, P < 0.05).

CONCLUSIONS

Omeprazole is effective in reducing esophageal acid exposure in premature infants with pathological acid reflux on 24-h pH probe; however, the far more complex issues of safety and efficacy have yet to be addressed.

Acid and nonacid gastro-oesophageal reflux in neurologically impaired children: investigation with the multiple intraluminal impedance procedure

OBJECTIVES

The diagnosis of gastro-oesophageal reflux (GOR) is more difficult in children with neurological impairment because symptoms are often less interpretable and frequently go undetected. The use of combined pH and multiple intraluminal impedance allows for the detection of both acid (pH < 4) and nonacid (pH > 4) GOR episodes, in addition to the height of the refluxate and the total acid and bolus clearance time in this cohort.

METHODS

Sixteen neurologically impaired children (9 were fed nasogastrically, 7 were fed orally) underwent 12-hour combined pH and multiple intraluminal impedance.

RESULTS

There were a total of 425 reflux episodes during the study period, of which 239 (56.2%) were nonacid. The median of reflux episodes per hour was 1.8 (range, 0.2-6.3/h). The median height of the refluxate was 1.5 channels (range, 1.1-2.9); and 71.3% of reflux episodes reached the upper oesophagus, of which 52.4% were nonacid reflux events. On average there were more GOR events (both acid and nonacid) in the children who were fed via a nasogastric tube, and the median height of refluxate was also higher in this group. However, the median acid clearance time was longer (both proximal and distal) in the children who were fed orally (28.6 s vs 16.2 s proximally; 67.9 s vs 38.3 s distally). The median acid clearance time (21.7 s proximally; 39.5 s distally) was longer when compared with bolus clearance (14.9 s).

CONCLUSIONS

More than half of the reflux events in neurologically impaired children are nonacidic and would therefore go undetected by conventional pH metry. There are more reflux events in children fed nasogastrically than oral-fed children.

Perinatal Risk Factors for Cancer of the Esophagus and Gastric Cardia: A Nested Case-Control Study

BACKGROUND

We have previously hypothesized that preterm birth or impaired fetal growth may cause esophageal adenocarcinomas through gastroesophageal reflux early in life. In this study, we aimed to test if there is an association between gestational duration and birth weight on the one hand, and risk of esophageal and cardia adenocarcinoma on the other.

METHODS

We conducted a nested case-control study of 67 cases of esophageal adenocarcinoma and 93 cases of cardia adenocarcinoma, whereas 50 cases of squamous cell carcinoma were studied for comparison. Birth records of cases were traced. Three matched controls per case were randomly selected. Perinatal data were extracted from birth records.

RESULTS

Long gestational duration was associated with a decreased risk of cardia adenocarcinoma (P(trend) = 0.001) and a nonsignificant decreased risk of esophageal adenocarcinoma (P = 0.07), whereas no such association was found for esophageal squamous cell carcinoma (P = 0.96). Birth weight was not associated with risk of any of the studied cancers. Compared with lower maternal age (</=24 years) at giving birth, maternal age of 25 to 29 years were associated with a decreased risk of esophageal adenocarcinoma and squamous cell carcinoma (odds ratio, 0.4; 95% confidence interval, 0.2-0.9 and odds ratio, 0.3; 95% confidence interval, 0.1-0.8, respectively).

CONCLUSIONS

Numerical constraints hamper inference, but our results are somewhat consistent with the idea that future risk of esophageal and cardia cancer may in part be determined already perinatally or in infancy and give some limited support to the hypothesis that timing of birth influences risk.

Maternal steroid enhancement of fetal rabbit gastrointestinal motility

AIM

The purpose of the present study was to determine the potential maturational effects of maternal dexamethasone administration on fetal upper gastrointestinal motility.

METHODS

Nineteen pregnant rabbits were randomized into two groups (DEX and CONT) and studied on either day 24, 27 or 30 of pregnancy (term 31 days). The DEX group received intramuscular dexamethasone (DEX) 2 days before study and the controls received saline. Under ultrasound guidance, a needle was percutaneously inserted into each fetal stomach and fluorescein, labeled with color-coded microspheres, was injected. Two hours later, the length of fluorescein travel throughout the small intestine was measured. The percent motility was calculated by dividing the length of fluorescein travel by the total fetal small intestinal length x 100%.

RESULTS

All maternal and fetal rabbits survived. On day 24 the length of fluorescein travel and the percent motility of the DEX group were significantly longer than controls. There were no differences on either day 27 or 30. Fetal growth was significantly suppressed by a single course of DEX at all gestational ages.

CONCLUSIONS

Fetal rabbit gastrointestinal motility is significantly increased after prenatal steroids are given early in the last trimester (day 24 of a 31-day gestation). Although beneficial in end-organ maturation, the timing of prenatal steroid administration is crucial to minimize its potential detrimental effects on fetal somatic growth.

Relationship between respiratory control and feeding in the developing infant

Simultaneous breathing and nursing from a bottle or breast requires intricate coordination of the muscles that serve both respiration and feeding. During the buccopharyngeal phase of feeding reflex input to the brainstem from the oropharynx and larynx, as well as suprabulbar and chemoreceptor areas controls the sequential activity of the muscles of deglutition. Coordinated development of buccopharyngeal functions generally occurs by 35 weeks post-conceptional age in infants, but can be disrupted by respiratory disease or neuropathology. During the oesophageal phase of feeding, the bolus of food traverses the oesophagus and lower oesophageal sphincter, whose tone is also regulated by nuclei in the brainstem and modulated by respiratory drive. Control of the lower oesophageal sphincter gradually develops postnatally in premature infants. Although symptomatic gastro-oesophageal reflux can be problematic for the term or preterm infant, it does not appear that reflux is a common stimulus for apnoea of prematurity.

Discerning differences: gastroesophageal reflux and gastroesophageal reflux disease in infants

Gastroesophageal reflux (GER) is a frequently encountered problem in infancy; it commonly resolves spontaneously by 12 months of age. Caregivers are challenged to discriminate between physiologic GER and the much less common and more serious condition of pathologic gastroesophageal reflux disease (GERD). Pathologic GERD may require more extensive clinical evaluation and necessitate treatment. GERD may be primary or secondary; secondary GERD is associated with a number of genetic syndromes, chromosomal abnormalities, birth defects, or a host of neurologic conditions frequently seen in the newborn intensive care unit. This article reviews the unique anatomic, physiologic, developmental, and nutritional vulnerabilities of infants that make them susceptible to GER and GERD. The North American Society of Pediatric Gastroenterology and Nutrition have recently developed a comprehensive evidence-based clinical practice guideline that structures the diagnostic approach and treatment option in infants with suspected and confirmed GERD. These guidelines provide clear definitions of GER and GERD to aid the clinician in distinguishing between the 2 conditions. They emphasize the use of history and physical examination and discuss the indications for the use of other diagnostic procedures, such as upper gastrointestinal studies, nuclear medicine scintiscan, esophagogastroduodenoscopy with biopsy, and esophageal pH probe monitoring. Management of GERD begins with a nonpharmacologic approach; the emphasis is on positioning, a trial of a hypoallergenic formula, and thickening of feedings. When these measures fail to control symptoms, a trial of either histamine(2) antagonists or a proton pump inhibitor may be indicated. Finally, surgical treatment may be needed if all other management measures fail. New sleep recommendations for infants with GERD are now consistent with the American Academy of Pediatrics' standard recommendations. Prone sleep positioning is only considered in unusual cases, where the risk of death and complications from GERD outweighs the potential increased risk of sudden infant death syndrome (SIDS). The nursing care of infants with GER and GERD, as well as relevant issues for parent education and support, are reviewed and are essential elements in managing this common condition.

Paradoxical impact of body positioning on gastroesophageal reflux and gastric emptying in the premature neonate

OBJECTIVES

To combine manometry and impedance to characterize the mechanisms of gastroesophageal reflux (GER) and to explore their relation to the rate of gastric emptying (GE) and body position.

STUDY DESIGN

Ten healthy preterm infants (35 to 37 weeks' postmenstrual age) were studied with the use of a micromanometric/impedance assembly. Episodes of GER were identified by impedance, and the mechanism(s) of GER triggering and GER clearance were characterized. GE was determined with a C13Na-octanoate breath test.

RESULTS

Gastroesophageal reflux episodes (n=89) were recorded, consisting of 74% liquid, 14% gas, and 12% mixed. Transient lower esophageal sphincter relaxation (TLESR) was the predominant mechanism of reflux, triggering 83% of GER. Of 92 TLESRs recorded, 27% were not associated with reflux. Infants studied in the right lateral position had significantly (P <.01) more GER, a higher proportion of liquid GER (P <.05), and faster GE (P <.005) when compared with infants studied in the left lateral position.

CONCLUSIONS

In healthy preterm infants, GER is predominantly liquid in nature. Right-side positioning is associated with increased triggering of TLESR and GER despite accelerating GE.

Pharmacokinetics of a single oral dose of baclofen in pediatric patients with gastroesophageal reflux disease

Transient relaxation of the lower esophageal sphincter (TLESR) is the predominant mechanism of gastroesophageal reflux (GER) in adults and children. Baclofen [4-amino-3-(p-chlorophenyl)-butanoic acid], a gamma-aminobutyric acid (GABA)-B receptor agonist used for the management of spasticity, has been recently shown to significantly inhibit GER in healthy adults without any relevant side effects. The objective of this study was to evaluate the pharmacokinetics of baclofen in a pediatric population with GER disease. In an open-label single-dose pharmacokinetic study, eight children with the diagnosis of GER made on clinical grounds received an oral dose of baclofen, 2.5 mg. Blood samples were drawn from an indwelling venous catheter, and urine was collected during a postdose period of 8 hours. The concentration of baclofen in these body fluids was determined using a validated high-performance liquid chromatography (HPLC) method with electrochemical detection after OPA-sulfite derivatization. Pharmacokinetic data were analyzed using the nonlinear regression program Scientist. Serum concentration-time curves could be best described using a two-compartment open model with a lag time. Mean plasma clearance (Cl) was 315.9 mL/h/kg; volume of distribution (Vd) was 2.58 L/kg; and half-life (T(1/2)beta) was 5.10 hours. No side effects were noted. As half-lives were comparable with those found in adult studies, the risk for accumulation seems not greater in children than in adults. Body composition can have a strong influence on the Vd of baclofen and, therefore, on the dose needed to obtain therapeutic plasma levels. Dosing according to clearly defined age groups with the help of therapeutic drug monitoring seems preferable. In view of the negative correlation between body weight and Vd, dosing according to body weight using adult pharmacokinetic data does not seem an effective way for using baclofen in children.

Mechanisms of gastro-oesophageal reflux in preterm and term infants with reflux disease

BACKGROUND

Transient lower oesophageal sphincter relaxation (TLOSR) is the predominant mechanism of gastro-oesophageal reflux (GOR) in healthy infants but the mechanisms of GOR in infants with GOR disease (GORD) are poorly understood.

AIMS

To measure the occurrence of TLOSR, GOR, and gastric emptying (GE) rate in preterm and term infants with GORD.

PATIENTS

Thirty six infants were studied and grouped as normals or GORD based on a routine clinical assessment and confirmation of an assessment of GORD by reflux symptom charts and oesophageal pH monitoring.

METHODS

A micromanometric assembly incorporating a micro pH electrode recorded oesophageal motility and pH. GE rate was determined using the (13)C-octanoic acid breath test.

RESULTS

TLOSR was the predominant mechanism of GOR, triggering 50-100% of GOR episodes (median 91.5%). Abdominothoracic straining significantly increased the occurrence of GOR in association with TLOSR. In infants with GORD, the number of TLOSRs overall was similar to normals but the proportion of TLOSRs accompanied by acid GOR was significantly higher than in normals (16.5% v 5.7%, respectively; p<0.001). Infants with GORD had a similar GE rate to normals.

CONCLUSIONS

In infant GORD, acid reflux associated TLOSRs are abnormally common and likely to be a major contributing factor to the pathophysiology of GORD. Infants with GORD do not have delayed GE.

Patterns of antropyloric motility in fed healthy preterm infants

BACKGROUND

Antropyloric motility is important for regulation of gastric emptying and has not been adequately characterised in premature infants.

AIM

To evaluate fed patterns of antropyloric motility in premature infants.

SUBJECTS

Forty three healthy premature infants, 30-38 weeks of postmenstrual age.

METHODS

Postprandial antropyloric motility was measured using a micromanometric feeding assembly (outer diameter 1.8 mm) incorporating a pyloric sleeve sensor. The occurrence of isolated pyloric pressure waves (IPPWs) and antral pressure wave sequences (PWSs) was characterised. Sequences were further classified as being antegrade, synchronous, antegrade-synchronous, and retrograde according to the direction of propagation.

RESULTS

A total of 7289 pressure wave events were recorded, 48% IPPWs and 52% PWSs (18% antegrade, 12% synchronous, 13% antegrade-synchronous, 2% retrograde, and 7% undefined). IPPWs predominated in the first postprandial hour, peaking at 30-60 minutes. PWSs predominated in the period after one hour postprandially. Mean (SEM) half gastric emptying time was 42 (4) minutes.

CONCLUSIONS

Monitoring of antropyloric motor patterns in healthy premature infants indicates that the neuroregulatory mechanisms responsible for the coordination of antropyloric motility and gastric emptying are well developed by 30 weeks of postmenstrual age.

Ontogeny of fetal rabbit upper gastrointestinal motility

BACKGROUND

The gastrointestinal (GI) tract performs the digestion, propulsion, and absorption of nutrients both pre- and postnatally, although little is known about the development of fetal motility. We evaluated the development of GI motility using a novel fetal rabbit model.

METHODS

Nine pregnant rabbits were obtained and three litters were studied at day 24 (n = 24), 27 (n = 29), and 30 (n = 24) of their 31-day gestation. Under ultrasound guidance fetal position was identified, a spinal needle was percutaneously inserted into each fetal stomach, and fluorescein, labeled with color-coded microspheres, was injected. Two hours later, fetuses were delivered and weighed, and the small intestine was harvested. The absolute length of fluorescein traveled was measured by ultraviolet light optical density and the percentage motility was calculated by dividing the absolute length of fluorescein traveled by the total small intestinal length.

RESULTS

All injected fetuses survived. The length of fluorescein traveled significantly increased from day 24 (8.1 +/- 2.1 cm) to day 27 (18.8 +/- 4.6 cm) and 30 (22.6 +/- 5.2 cm). The length of fluorescein traveled significantly correlated with body weight on day 27 and 30. Calculated percentage motility significantly increased from day 24 to 30. However, percentage motility showed no correlation with fetal weight.

CONCLUSIONS

This study describes a novel rabbit model for the assessment of in vivo fetal GI motility. Motility matured during the last third of gestation when assessed by the absolute length of fluorescein travel and the percentage motility. These results confirm that late-gestation fetuses have developed sufficient motility to propel potential nutrients, drugs, or gene therapy vectors to the small intestinal absorptive surface area.

Characterization of anorectal pressure and the anorectal inhibitory reflex in healthy preterm and term infants

OBJECTIVES

To evaluate anorectal motor function in healthy premature and term infants with the use of micromanometric techniques.

STUDY DESIGN

Anorectal manometry was performed in 22 healthy neonates (9 female) with a mean postmenstrual age of 32 weeks (range, 30 to 38 weeks) with a micromanometric anorectal assembly (od 2.0 mm). The assembly incorporated a 2-cm-long sleeve sensor for measurement of resting anal sphincter pressures and relaxation, and 4 sideholes recorded anal and rectal pressures. Rectal distension was performed with a latex balloon or direct air insufflation to elicit the anorectal inhibitory reflex (AR).

RESULTS

The mean anal sphincter pressure, rectal pressure, and rhythmic wave frequency were 40 mm Hg (range, 7 to 65 mm Hg), 11 mm Hg (range, 1 to 27 mm Hg), and 10/min (range, 8 to 14/min), respectively. A normal AR could be elicited in 21 of the 22 infants studied.

CONCLUSION

An anorectal micromanometric sleeve catheter is suitable for use in evaluating anorectal pressures in preterm and term neonates. Insufflation of air without the use of a balloon to elicit the AR is reliable and suitable for use in infants <34 weeks. Premature infants older than 30 weeks' postmenstrual age have normal anorectal pressures and a normal AR.

Oroesophageal motor disorders in Pierre Robin syndrome

BACKGROUND

Feeding disorders are one of the main clinical features in PRS, which combines a posterior U-shaped cleft palate, retrognathia, and glossoptosis. The aim of this study was to evaluate the oral and esophageal motor function of children with PRS without additional neurologic symptoms.

METHODS

All children hospitalized with Pierre Robin syndrome either isolated (n = 27) or associated with Stickler syndrome (n = 8) were included. Clinical evaluation of their oroesophageal disorders and systematic esophageal manometry were performed.

RESULTS

Feeding disorders were always present, but type of disorder varied from one child to another. Esophageal disorders were frequent and seemed to be resistant to classic gastroesophageal reflux treatment. Eighty-six percent of the children required nasogastric tube feeding for a mean duration of 8.6 months. Esophageal manometric abnormalities were noted in 50% of the children: lower esophageal sphincter hypertonia, failure of lower esophageal sphincter relaxation at deglutition, and esophageal dyskinesia. These clinical and manometric disorders showed a trend to spontaneous regression after 12 months.

CONCLUSION

In the current Pierre Robin syndrome series, clinical and manometric anomalies of oroesophageal motility were always present. The authors identified an unusual manometric pattern that has also been described in situations of neurovegetative instability. It could reflect dysregulation of the control of the central pattern generators of swallowing in the brain stem.

Reflux in children

Gastro-oesophageal reflux (GOR) is an extremely common paediatric problem that often runs a harmless and self-limited course. Physiological GOR however can lead to marked parental anxiety, many unnecessary investigations and often unwarranted and potentially harmful therapeutic interventions. Our ability to better define GOR and gastro-oesophageal reflux disease (GORD) has improved in the past 15 years with a better understanding of the pathophysiology in infants and children due to the development and wider use of flexible endoscopy, 24-hour oesophageal pH monitoring and, more recently, the use of micromanometric methods for studying oesophageal motility. This will be further enhanced in the future with the development of non-invasive breath testing to study gastrointestinal motility and the use of electrical impedance to study fluid movement. Our therapeutic interventions have also improved particularly in the areas of acid suppression, improved surgical techniques and most recently laparoscopic fundoplication. This chapter reviews these advances in the paediatric area especially with regard to pathophysiology, diagnostic testing and therapeutic intervention.

Gastroesophageal reflux disease in children

In the pediatric population, gastroesophageal reflux most often presents in infancy as effortless regurgitation, but pathologic GERD is accompanied by signs of malnutrition, respiratory diseases, and esophagitis or its complications. Because of the distinctive pathophysiology predisposing infants to GERD, the diagnostic approach must begin with a thorough history that determines the extent of further diagnostic tests and the course of management. Empiric therapy assumes importance in infants with GERD because of the limited differential diagnoses in consideration. Conservative therapy is of utmost importance because of the unique provocative factors in the pathophysiology of infantile GERD. Prokinetic pharmacotherapy takes precedence over acid suppression because of the more important role of motility factors compared with acid secretion in infantile GERD.

Mechanism of gastroesophageal reflux in premature infants with chronic lung disease

BACKGROUND/PURPOSE

The aim of this study was to characterize the motor events responsible for gastroesophageal reflux (GER) and esophageal acid clearance in a cohort of preterm infants with chronic lung disease (CLD).

METHODS

Esophageal motility was recorded for 2 to 3 hours postprandially in 14 preterm infants with mild-moderate or moderate-severe CLD at 33 to 39 weeks postmenstrual age using a sleeve-side hole micromanometric assembly into which a pH probe had been installed.

RESULTS

Twenty-six acid GER episodes were recorded by pH probe. Of these, 22 (85%) were associated with transient lower esophageal sphincter (LES) relaxation. Transient LES relaxations were significantly longer in duration than single swallows (13.7 seconds v 4.6 seconds, P < .001) and had lower nadir pressures (1.1 mm Hg v 2.5 mm Hg, P < .001). During periods of esophageal acidification (pH below 4), peristaltic esophageal body pressure wave sequences cleared acid refluxate more effectively than nonperistaltic pressure wave sequences.

CONCLUSIONS

In preterm infants with CLD, transient LES relaxations are the predominant mechanism underlying GER, and esophageal clearance mechanisms are fully functional, which is similar to that seen in healthy preterm infants.

Prone and left lateral positioning reduce gastro-oesophageal reflux in preterm infants

AIM

To examine the effect of body position on clinically significant gastro-oesophageal reflux (GOR) in preterm infants.

METHODS

Eighteen preterm infants with clinically significant GOR were studied prospectively using 24 hour lower oesophageal pH monitoring. Infants were nursed in three positions (prone, left, and right lateral) for 8 hours in each position, with the order randomly assigned. Data were analysed using analysis of covariance.

RESULTS

The median (range) reflux index (RI) for the group was 13.8% (5.8-40. 4). There was no significant difference in the mean time spent in each position. RI (mean % (SEM)) was significantly less in prone (6. 3 (1.7)) and left lateral positions (11.0 (2.2)), when compared with the right lateral position (29.4 (3.2)); p<0.001. The mean (SEM) longest episodes (mins) of GOR were reduced by prone and left positions (8.6 (2.2) and 10.0 (2.4), respectively) compared with the right position (26.0 (3.9)); p<0.001. The mean (SE) number of episodes was reduced by prone (15.4 (2.8)) and left (24.6 (3.5)) positions when compared with right (41.6 (4.6)) (p<0.001).

CONCLUSIONS

Prone and left lateral positions significantly reduce the severity of GOR, by reducing the number of episodes and the duration of the longest episodes. Such positioning offers a useful adjunct to the treatment in hospital of preterm infants with gastro-oesophageal reflux.

Measurement of upper esophageal sphincter tone and relaxation during swallowing in premature infants

Upper esophageal sphincter (UES) motor function has not been previously evaluated in premature infants. The motor patterns associated with tonic activity and swallow-related relaxation of the UES were recorded for 1 h after completion of gavage feeding in 11 healthy preterm neonates (postmenstrual age 33-37 wk) with a micromanometric assembly, which included a sleeve sensor specifically adapted for UES recordings. A clearly defined UES high-pressure zone was observed in all premature infants studied. Resting UES pressure ranged from 2.3 to 26.2 mmHg and was higher during periods of irritability and apparent discomfort. During dry swallows, UES pressure relaxed from a resting pressure of 28.2 +/- 4.0 mmHg to a nadir of 1.1 +/- 3.3 mmHg. The mean UES relaxation interval (the time from relaxation onset to relaxation offset) was 0. 31 +/- 0.11 s. We conclude that in premature infants >/=33 wk postmenstrual age the motor mechanisms regulating UES resting pressure and the onset of UES relaxation are well developed.

Lower esophageal sphincter position in premature infants cannot be correctly estimated with current formulas

OBJECTIVES

Strobel's formula (Esophageal length = 5 + 0.252 x Height) is frequently used as a guide for determining the distance from the nares to the lower esophageal sphincter (LES) in term infants. The aim of this study was to examine this relationship in premature infants.

STUDY DESIGN

The distance from nares to LES was manometrically determined in 156 premature infants (26-40 weeks' postmenstrual age; body weights of 610-3050 g). The ability of body weight, height (body length), head circumference, and postmenstrual age to predict the manometrically determined LES position was evaluated with linear and non-linear regression analyses.

RESULTS

Body weight and body length were the most predictive of distance from nares to LES (r(2) = 0.848 and 0.802, respectively). These relationships were non-linear and, in the case of body length, deviated substantially from Strobel's model.

CONCLUSIONS

In premature neonates, a different formula is needed for prediction of the distance between nares and LES than that applied to term infants and children.

Characterization of esophageal body and lower esophageal sphincter motor function in the very premature neonate

OBJECTIVES

To characterize esophageal body and lower esophageal sphincter (LES) motor function in very premature infants.

STUDY DESIGN

Esophageal manometry was performed in 12 very premature infants of 26 to 33 weeks' postmenstrual age (PMA) (body weights of 610-1360 g). Esophageal motor patterns were recorded for 30 minutes with a perfused micromanometric sleeve assembly (outer diameter, 2.0 mm).

RESULTS

Esophageal pressure waves triggered by dry swallows were predominantly (84%) peristaltic in propagation sequence. All infants showed tonic LES contraction; the mean resting LES pressure (LESP) for individual infants ranged from 5.0 +/- 4.1 mm Hg to 20.0 +/- 4.8 mm Hg. In all infants the LES relaxed (duration, 5.8 +/- 3.0 seconds; nadir pressure, 1.8 +/- 2.6 mm Hg) in response to pharyngeal swallows. Transient LES relaxations (TLESRs) (duration, 21.7 +/- 8.7 seconds; nadir pressure, 0.1 +/- 1.8 mm Hg) occurred on average 2.6 +/- 1.6 times per study; 86% of these relaxations triggered esophageal body common cavity events known to be associated with gastroesophageal reflux.

CONCLUSIONS

Esophageal motor function is well developed in very premature infants. Our data also suggest that TLESR is the predominant mechanism of reflux in these babies.

Reproducibility of the 13C-octanoic acid breath test for assessment of gastric emptying in healthy preterm infants

BACKGROUND

The 13C-octanoic acid breath test has been used to measure gastric emptying in preterm infants, but the reproducibility of the test has not been evaluated in this population.

METHODS

Fifty-six paired breath test analyses were performed on 28 healthy preterm infants 1 to 5 days apart using the same food type, volume, and energy content for each paired sample. Breath samples were taken before the feeding, at 5-minute intervals after feeding for 30 minutes, then each 15 minutes for 4 hours. Samples were analyzed using an isotope-ratio mass spectrometer, and 3C recovery was used to calculate values for gastric-emptying coefficient and gastric half-emptying time.

RESULTS

There was no significant difference between test results on different days in the paired samples studied. gastric-emptying coefficients for the first and subsequent samples were 2.6+/-0.1 (mean+/-SEM) and 2.7+/-0.1, respectively, and half-emptying times were 44.5+/-3.7 minutes and 41.4+/-3.2 minutes.

CONCLUSION

The 13C-octanoic acid breath test is a reliable, noninvasive, and reproducible measure of gastric emptying in preterm infants that should have wide application for use in this population.

Gastro-oesophageal reflux in infancy

Gastro-oesophageal reflux (GOR) is a common phenomenon in infants, which may occur with or without accompanying symptoms. Although most infants presenting with regurgitation have a normal physical examination, it is now recognized that infants may also present with a wide variety of symptoms. Oesophagitis is associated with increased oesophageal acid exposure. The determination of cause and effect is difficult, as there are many aspects of reflux disease where cause and effect relationships are cyclic. Reflux disease is present when there is an imbalance between a number of factors that can contribute to a decrease, as well as an increase, of GOR. Oesophageal pH monitoring with a semi-disposable monocrysant antimony pH catheter with three sensors is very good at documenting oesophageal acidification and gastric buffering and, therefore, quantifies acid reflux frequency and duration. However, the interpretation of the data is complex as they are influenced by numerous factors, such as position, activity (sleep, crying), feeding (frequency and composition) or medication. The duration of buffering of gastric acidity during pH monitoring might, in the future, appear to be a relevant factor in the interpretation of oesophageal pH data.

Mechanisms of gastroesophageal reflux in healthy premature infants

OBJECTIVES

The aim of this study was to characterize the motor events responsible for gastroesophageal reflux (GER) and esophageal acid clearance in a cohort of healthy preterm infants.

STUDY DESIGN

Esophageal motility was recorded for 2 to 3 hours after a feeding in 24 preterm infants, 31 to 38 weeks' postmenstrual age, by using a sleeveside hole micromanometric assembly incorporating a pH probe.

RESULTS

Sixty acid GER episodes were recorded by pH probe, and 133 non-acid GER episodes were recorded manometrically by the presence of esophageal common cavities. Of the 193 GER episodes, 159 (82%) were associated with transient lower esophageal sphincter relaxation (TLESR). TLESRs were significantly longer in duration than single swallows (15.1 seconds vs 5.6 seconds, P < .001) and had lower nadir pressures (0.8 mm Hg vs 2.3 mm Hg, P < .001). A total of 3216 esophageal body pressure waves were analyzed; 70% of swallow-induced pressure waves were peristaltic in sequence compared with 5% of swallow-unrelated pressure waves. During periods of esophageal acidification (pH below 4), peristaltic esophageal body pressure wave sequences cleared acid refluxate more effectively than nonperistaltic pressure wave sequences.

CONCLUSIONS

In healthy preterm infants, TLESRs are the predominant mechanism underlying GER, and esophageal clearance mechanisms are well developed by at least 31 weeks' postmenstrual age.

Patterns of lower esophageal sphincter function associated with gastroesophageal reflux

Studies in which lower esophageal sphincter and esophageal pH have been monitored simultaneously have challenged the traditional concept that most reflux episodes result from weak steady state lower esophageal sphincter tone. Instead, the majority of reflux episodes have occurred during 5-35-second abrupt periods of complete sphincter relaxation usually against a background of normal sphincter tone. This distinctive pattern of relaxation, which has been named "transient lower esophageal sphincter relaxation," occurs independently of swallowing. It depends on vagal pathways and the hindbrain for its patterning and control, but many of these aspects are still not well understood. Control of transient lower esophageal sphincter relaxation by drug therapy is an attractive future option for management of supraesophageal complications of reflux disease.