Mechanism of gastroesophageal reflux in premature infants with chronic lung disease

Characterizing Esophageal Motility in Neonatal Intensive Care Unit Patients Using High Resolution Manometry

OBJECTIVE

To characterize esophageal motility and esophago-gastric junction (EGJ) function during feeding in neonatal intensive care unit (NICU) patients.

PATIENTS AND METHODS

High resolution manometry with impedance (HRIM) was used to investigate esophageal motility and EGJ function in patients admitted to the NICU. Twenty-eight preterm born infants with bronchopulmonary dysplasia (BPD), 12 born with isolated congenital diaphragmatic hernia (iCDH), and 10 with esophageal atresia (EA) were included. Thirteen healthy infants were included as controls. Esophageal motility and EGJ function were analyzed using objective esophageal bolus transport parameters.

RESULTS

Normal esophageal peristaltic wave patterns were observed in all investigated infants without EA. Nine of 10 patients with EA presented with abnormal esophageal motor wave patterns. A total of 224 nutritive swallows were analyzed (controls, n = 48; BPD, n = 96; iCDH, n = 60; EA, n = 20). Infants with BPD and iCDH had similar distal contractile strength (DCI) compared to healthy controls, while in patients with EA, DCI was significantly lower (Kruskal-Wallis test, p = 0.001). In most infants, EGJ relaxation after swallowing was unaffected. EGJ barrier function, in terms of EGJ-contractile integral, also appeared well-developed and did not differ significantly among patient groups.

CONCLUSIONS

We conclude that esophageal motility studies using pressure-impedance analysis are feasible in young infants. Bolus transport mechanisms following nutritive swallows appeared well-established in all investigated infants with the exception of those with EA. EGJ relaxation was also functional after deglutition and EGJ function as an anti-reflux barrier appeared well-developed in all investigated NICU groups.

Characterization of esophageal motility and esophagogastric junction in preterm infants with bronchopulmonary dysplasia

BACKGROUND

To characterize esophageal motility and function of the esophagogastric junction (EGJ) in preterm infants with bronchopulmonary dysplasia (BPD).

METHODS

High-resolution manometry with impedance was used to investigate esophageal motility and EGJ function in 28 tube-fed preterm infants with BPD. Patients with BPD were studied at term age during oral feeding. Thirteen healthy term-aged infants were included as controls. Esophageal analysis derived objective measures to evaluate esophageal contractile vigor, bolus distension pressure, EGJ relaxation, and EGJ barrier function (in rest and during respiration). In addition, we investigated the effect of BPD severity on these measures.

KEY RESULTS

A total of 140 nutritive swallows were analyzed (BPD, n = 92; controls, n = 48). Normal esophageal peristaltic wave patterns were observed in all infants. BPD patients had higher distal contractile esophageal strength compared with controls (Kruskal-Wallis (KW) P = .048), and their deglutitive EGJ relaxation was comparable to controls. Severe BPD patients showed higher bolus distension pressures, higher EGJ resting pressures, and increased EGJ contractile integrals compared with mild BPD patients (Mann-Whitney U P = .009, KW P = .012 and KW P = .028, respectively).

CONCLUSIONS AND INFERENCES

Preterm infants with BPD consistently present with normal peristaltic esophageal patterns following nutritive liquid swallows. The EGJ barrier tone and relaxation pressure appeared normal. In general, infants with BPD do not have altered esophageal motor function. There is however evidence for increased flow resistance at the EGJ in severe BPD patients possibly related to an increased contractility of the diaphragm.

Prolonging gavage feeds for reduction of gastroesophageal reflux in infants

OBJECTIVE

To determine if prolonging gavage feedings in infants for ≥60 min is associated with decreased gastroesophageal reflux (GER) compared with bolus feeding using multiple-channel intraluminal impedance with pH probe (MII-pH).

STUDY DESIGN

Retrospective analysis of infants who underwent MII-pH between October 2009 and July 2018 and received gavage feedings. Infants were divided into two groups: bolus (<30 min) or prolonged (≥60 min). Symptoms, number of reflux events and percent time pH < 4 was compared.

RESULT

Fifty-eight infants underwent evaluation. Thirty-one (54%) received bolus gavage feedings and 27 (46%) received prolonged feedings. Groups differed in postmenstrual age. Total reflux episodes were significantly lower with prolonged feeding (median 19 vs. 28 episodes, p = 0.015), with no difference in acid exposure time. There was no significant difference in GER symptoms between the two groups.

CONCLUSION

Prolongation of gavage feedings was associated with decreased total numbers of GER events without reduction in GER symptoms.

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.

Nutritional Intervention of a Pediatric Patient with Congenital Bronchomalacia and Gastroesophageal Reflux Disease: a Case Report

Gastroesophageal reflux disease (GERD) is closely related to respiratory issues. We reported the case about the nutrition intervention given to a male infant with congenital bronchomalacia, GERD, and recurrent pneumonia. During the first and second pediatric intensive care unit (PICU) stays, his nutrition status and nutrient intake were good. However, during the 18 days of the third PICU admission, his nutrient intake decreased to 75%–80% of his estimated calorie requirement and his Z-score for weight-for-age dropped to −1.4. We conducted nutritional interventions to improve GERD symptoms and nutritional status include avoiding overfeeding by feeding small amounts frequently, using a pre-thickened formula mixed with a high-calorie formula, and feeding through transpyloric tube. As a result, his daily nutrient intakes gradually increased and his Z-score for weight-for-age was normal. In conclusion, it is important to implement individualized intensive nutritional management to ensure adequate nutrition and growth status in infants with lung disease and GERD.

Gastroesophageal Reflux in Neurologically Impaired Children: What Are the Risk Factors?

Background/Aims

Neurologically impaired patients frequently suffer from gastrointestinal tract problems, such as gastroesophageal reflux disease (GERD). In this study, we aimed to define the risk factors for GERD in neurologically impaired children.

Methods

From May 2006 to March 2014, 101 neurologically impaired children who received 24-hour esophageal pH monitoring at Severance Children’s Hospital were enrolled in the study. The esophageal pH finding and the clinical characteristics of the patients were analyzed.

Results

The reflux index was higher in patients with abnormal electroencephalography (EEG) results than in those with normal EEG results (p=0.027). Mitochondrial disease was associated with a higher reflux index than were epileptic disorders or cerebral palsy (p=0.009). Patient gender, feeding method, scoliosis, tracheostomy, and baclofen use did not lead to statistical differences in reflux index. Age of onset of neurological impairment was inversely correlated with DeMeester score and reflux index. Age at the time of examination, the duration of the disease, and the number of antiepileptic drugs were not correlated with GER severity.

Conclusions

Early-onset neurological impairment, abnormal EEG results, and mitochondrial disease are risk factors for severe GERD.

Tracheobronchomalacia Is Associated with Increased Morbidity in Bronchopulmonary Dysplasia

RATIONALE

Tracheobronchomalacia is a common comorbidity in neonates with bronchopulmonary dysplasia. However, the effect of tracheobronchomalacia on the clinical course of bronchopulmonary dysplasia is not well-understood.

OBJECTIVE

We sought to assess the impact of tracheobronchomalacia on outcomes in neonates with bronchopulmonary dysplasia in a large, multi-center cohort.

METHODS

We preformed a cohort study of 974 neonates with bronchopulmonary dysplasia admitted to 27 neonatal intensive care units participating in the Children's Hospital Neonatal Database who had undergone bronchoscopy. In hospital morbidity for neonates with bronchopulmonary dysplasia and tracheobronchomalacia (N=353, 36.2%) was compared to those without tracheobronchomalacia (N=621, 63.8%) using mixed-effects multivariate regression.

RESULTS

Neonates with tracheobronchomalacia and bronchopulmonary dysplasia had more comorbidities, such as gastroesophageal reflux (OR=1.65, 95%CI 1.23- 2.29, P=0.001) and pneumonia (OR=1.68, 95%CI 1.21-2.33, P=0.002) and more commonly required surgeries such as tracheostomy (OR=1.55, 95%CI 1.15-2.11, P=0.005) and gastrostomy (OR=1.38, 95%CI 1.03-1.85, P=0.03) compared with those without tracheobronchomalacia. Neonates with tracheobronchomalacia were hospitalitized (118 ± 93 vs 105 ± 83 days, P=0.02) and ventilated (83.1 ± 91.1 vs 67.2 ± 71.9 days, P=0.003) longer than those without tracheobronchomalacia. Upon discharge, neonates with tracheobronchomalacia and BPD were more likely to be mechanically ventilated (OR=1.37, 95CI 1.01-1.87 P=0.045) and possibly less likely to receive oral nutrition (OR=0.69, 95%CI 0.47-1.01, P=0.058).

CONCLUSIONS

Tracheobronchomalacia is common in neonates with bronchopulmonary dysplasia who undergo bronchoscopy and is associated with longer and more complicated hospitalizations.

Effects of Esophageal Acidification on Troublesome Symptoms: An Approach to Characterize True Acid GERD in Dysphagic Neonates

To quantify and compare maximal extent (height) of acid reflux events (AREs) on symptom generation in dysphagic neonates. Dysphagic neonates (N = 53), born at 30 ± 5.3 weeks gestation, underwent 24-hour pH-impedance study for the evaluation of troublesome symptoms purported to be due to gastroesophageal reflux disease (GERD). AREs (pH < 4 for >4 s) detected by impedance (Z) were categorized by maximal extent as refluxate reaching distal (Z6, Z5), middle (Z4, Z3), or proximal (Z2, Z1) impedance channels. AREs reaching the pH sensor only were categorized as distal. Symptom correlation (%, symptom index, symptom sensitivity index, and symptom associated probability) and temporal characteristics (clearance times) of AREs were analyzed using linear mixed and GEE models comparing height categories presented as mean ± SEM, median (IQR), and OR (95% CI). Of the 2003 AREs, 1) distal extent AREs (n = 1642) had increased frequency (p < 0.05), decreased ACT (p < 0.05), and decreased acidity (p < 0.05); 2) in middle and proximal AREs, acid clearance was longer than bolus clearance, (p < 0.01); and 3) the odds of having cardiorespiratory (cough or sneeze) symptoms are increased with proximal and middle AREs (p < 0.05). Most proximal ascent of AREs into middle or proximal esophagus likely activates protective aerodigestive reflexes (peristalsis) or vigilant states to facilitate bolus and chemical clearance. Heightened esophageal sensitivity, acid neutralization delays, or clearance mechanism delays may accentuate multi-systemic troublesome symptoms.

Are Infants with Bronchopulmonary Dysplasia Prone to Gastroesophageal Reflux? A Prospective Observational Study with Esophageal pH-Impedance Monitoring

OBJECTIVE

To perform an observational cohort study with esophageal pH-multichannel intraluminal impedance (pH-MII) monitoring in symptomatic preterm infants with and without bronchopulmonary dysplasia (BPD).

STUDY DESIGN

We prospectively studied 46 infants born ≤32 weeks gestational age: 12 infants with BPD and 34 infants without BPD. Each patient had symptoms consistent with gastroesophageal reflux and had 24-hour pH-MII, which were compared between BPD and non-BPD by univariate analysis and quantile regression analysis.

RESULTS

Demographic and clinical characteristics were similar between infants with and without BPD, except for fluid administration (145 vs 163 mL/kg/d, P = .003), length of stay (92 vs 69 days, P = .019), and time to achieve complete oral feeding (76 vs 51 days, P = .013). The analysis of 1104 hours of pH-MII tracings demonstrated that infants with BPD compared with infants without BPD had increased numbers of pH-only events (median number 21 vs 9) and a higher symptom sensitivity index for pH-only events (9% vs 4.9%); the number and characteristics of acid, weakly acid, nonacid and gas gastroesophageal reflux events, acid exposure, esophageal clearance, and recorded symptoms did not significantly differ between the 2 groups.

CONCLUSIONS

The increased number of (and sensitivity for) pH-only events among infants with BPD may be explained by several factors, including lower milk intake, impaired esophageal motility, and a peculiar autonomic nervous system response pattern.

Myth: gastroesophageal reflux is a pathological entity in the preterm infant

There is concern about possible consequences of gastroesophageal reflux (GER) in preterm infants. GER is perceived to be a frequent condition in these infants, often causing an exhaustive investigation and expensive therapy. We review current evidence for and against an association between GER and apnea, failure to thrive, wheezing and respiratory diseases. Although there are some limitations to the methodologies currently used for detecting GER, there is clearly a lack of unequivocal evidence supporting a causal relationship between GER and its assumed consequences, particularly in preterm infants. Despite physiologic data that stimulation of laryngeal efferents by GER may induce apnea, there is little evidence for a causal relationship between GER and apnea. Studies on preterm infants with failure to thrive have also not demonstrated an association between the latter and GER in most cases, and there is equally little evidence for a casual relationship with respiratory problems. Therefore, we believe that GER in preterm infants is only rarely associated with serious consequences and existing evidence does not support the widespread use of anti-reflux medications for treatment of these signs in this age group. An improvement of methods to identify the few preterm infants at risk for developing serious consequences of GER is urgently needed.

Apnea-associated reduction in lower esophageal sphincter tone in premature infants

OBJECTIVE

To characterize esophageal motility during episodes of prolonged apnea in premature infants.

STUDY DESIGN

We retrospectively reviewed combined manometric and physiological monitoring studies performed in tube-fed premature infants from 1994 to 2002. Apnea was defined as a respiratory pause of >20 seconds. For each apneic event, pharyngeal swallowing, esophageal motility, and lower esophageal sphincter (LES) pressure were assessed before, during, and after apneic episodes.

RESULTS

Twelve episodes of apnea (duration, 20 to 120 seconds) were identified in 7 infants (34 to 37 weeks postmenstrual age (PMA); study weight, 1950 to 2380 g). During the apneic episodes, swallowing increased (median[interquartile range], 0[0,0], 5[4,7], and 1[0,2] swallows/minute before, during, and after apnea, respectively; P < .05), esophageal pressure wave sequences (PWS) increased (1[0,2], 5[3,6], and 2[1,3] PWS/minute before, during, and after apnea, respectively; P < .05) and LES pressure decreased (16[12,21], 6[5,8], and 27[12,32] mmHg before, during, and after apnea, respectively; P < .05).

CONCLUSION

In premature infants, apnea is associated with reduced LES tone, potentially increasing the likelihood of reflux occurring after the onset of apnea.

Esophageal smooth muscle reactivity is impaired in chronic reflux esophagitis by both receptor- and nonreceptor-mediated mechanisms

AIM

Esophagitis is associated with an impaired esophageal peristalsis. A few studies have been aimed at understanding the pathophysiology of abnormal peristaltic activity. The mechanism of impaired esophageal smooth muscle reactivity in the chronic gastroesophageal reflux (GER) model is investigated in vitro for the first time.

MATERIALS AND METHODS

The chronic GER rat model was created by partial gastric outlet obstruction. The histopathological findings related to esophagitis were evaluated. Smooth muscle strips of the tunica muscularis mucosa of esophagus were studied in standard organ chambers. Carbachol- and KCl-induced contractile responses and serotonin- and papaverine- induced relaxant responses in both reflux and sham-operated control groups were determined.

RESULTS

Histopathologically, chronic reflux esophagitis was observed in all specimens of the reflux group. Contractile (carbachol- and KCl-induced) smooth muscle responses were significantly decreased in the reflux group. When compared to control group, relaxant response of smooth muscle to serotonin was also significantly decreased in the reflux group. However, there was no difference in papaverine-induced relaxant responses between 2 groups.

CONCLUSIONS

Our study describes the effects of chronic GER on rat esophageal smooth muscle contractility in vitro. We found that both receptor- (carbachol, serotonin) and nonreceptor-mediated (KCl) esophageal smooth muscle reactivity were impaired in chronic reflux esophagitis. These changes may correspond to the functional motor abnormalities of the esophagus seen in patients with chronic reflux esophagitis.

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.

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.

Mechanisms of gastroesophageal reflux and gastroesophageal reflux disease

Gastroesophageal reflux is a physiological phenomenon, occurring with different severity and duration in different individuals. Reflux occurs when this normal event results in the occurrence of symptoms/signs or complications. The pathophysiology of gastroesophageal reflux is complex and diverse, since it is influenced by factors that are genetic, environmental (e.g., diet smoking), anatomic, hormonal, and neurogenic. However, many mechanisms remain incompletely understood. Future research should focus on a better understanding of the physiology of the upper and lower esophageal sphincters, and of gastric motility. The afferent and efferent neural pathways and neuropharmacologic mediators of transient lower esophageal sphincter relaxations and gastric dysmotility require further study. The role of anatomic malformations such as hiatal hernia in children has been underestimated. While therapeutic possibilities are greater in number and largely improved, the outcomes of some treatments are far from satisfactory in many cases. In addition to development of new forms of treatment, research should address better use of currently available medical and surgical treatments.

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.