Esophageal body and upper esophageal sphincter motor responses to esophageal provocation during maturation in preterm newborns

Coordination of Pharyngeal and Esophageal Phases of Swallowing

Although swallowing has been reviewed extensively, the coordination of the phases of swallowing have not. The phases are controlled by the brainstem, but peripheral factors help coordinate the phases. The occurrence, magnitude, and duration of esophageal phase depends upon peripheral feedback activated by the bolus. The esophageal phase does not occur without peripheral feedback from the esophagus. This feedback is mediated by esophageal slowly-adapting mucosal tension receptors through the recurrent and superior laryngeal nerves. A similar reflex mediated by the same peripheral pathway is the activation of swallowing by stimulation of the cervical esophagus. This reflex occurs primarily in human infants and animals, and this reflex may be important for protecting against aspiration after esophago-pharyngeal reflux. Not only are there inter-phase excitatory processes, but also inhibitory processes. A significant inhibitory process is deglutitive inhibition. When one swallows faster than peristalsis ends, peristalsis is inhibited by the new pharyngeal phase. This process prevents the ongoing esophageal peristaltic wave from blocking the bolus being pushed into the esophagus by the new wave. The esophageal phase returns during the last swallow of the sequence. This process is probably mediated by mucosal tension receptors through the superior laryngeal nerves. A similar reflex exists, the pharyngo-esophageal inhibitory reflex, but studies indicate that it is controlled by a different neural pathway. The pharyngo-esophageal inhibitory reflex is mediated by mucosal tension receptors through the glossopharyngeal nerve. In summary, there are significant peripheral processes that contribute to swallowing, whereby one phase of swallowing significantly affects the other.

Proton pump inhibitor therapy may alter the sensory motor characteristics of pharyngoesophageal motility in infants with suspected GERD

BACKGROUND

Acid reflux index (ARI) is a biomarker for gastroesophageal reflux disease (GERD). The effects of short-term proton pump inhibitor (PPI) therapy on pharyngoesophageal motility and clearance mechanisms in infants remain unknown. We hypothesized that pharyngoesophageal reflexes and response to PPI are distinct between infants with 3%-7% and >7% ARI.

METHODS

Secondary analysis was performed from a subset of infants who participated in a randomized controlled trial (NCT: 02486263). Infants (N = 36, 29.9 ± 4.3 weeks gestation) underwent 4 weeks of PPI therapy, 1 week of washout, and longitudinal testing to assess: (a) clinical outcomes; (b) pH-impedance and symptom metrics including ARI, distal baseline impedance, clearance time, refluxate height, symptoms, I-GERQ-R scores, symptom association probability; (c) pharyngoesophageal motility reflexes and sensory motor characteristics. Comparisons were performed between infants with 3%-7% versus >7% ARI.

KEY RESULTS

From the 36 hospitalized infants treated: Pharyngoesophageal reflex latencies were prolonged (p > 0.05) and duration in ARI 3%-7% group only (p = 0.01); GER frequency, proximal ascent and clearance increased (ARI 3%-7%); weight gain velocity, oral feeding success, and fine motor score decreased while length of hospital stays increased in the ARI >7% group despite the decrease in symptoms and I-GERQ-R scores.

CONCLUSIONS & INFERENCES

Distinct changes in pharyngoesophageal sensory motor aspects of motility and reflex mechanisms exist after using PPI therapy in infants. Contributory factors may include the effects of maturation and aerodigestive comorbidities (GERD and BPD). Controlled studies incorporating placebo are needed to delineate the effects of PPI on causal and adaptive GERD mechanisms in infants with aerodigestive and feeding-related comorbidities.

Characteristics of esophageal refluxate and symptoms in infants compared between pre-treatment and on treatment with proton pump inhibitors

OBJECTIVE

To examine longitudinal pH-impedance characteristics from those infants who remained on proton pump inhibitors therapy for gastroesophageal reflux disease (GERD) as parents/providers refused to discontinue therapy after 4 weeks.

STUDY DESIGN

Eighteen infants with acid reflux index >3% underwent treatment, and pH-impedance data were compared prior to and on proton pump inhibitors at 42 ± 1 and 46 ± 1 weeks' postmenstrual age, respectively. Esophageal acid and bolus exposure, symptoms and swallowing characteristics were examined.

RESULTS

Proton pump inhibitors reduces the acid-mediated effects of reflux but modifies impedance and clearance mechanisms (P < 0.05). Prolonged therapy did not reduce symptoms (P > 0.05). Infants evaluated while on proton pump inhibitors were 1.8 times more likely to have swallows before and after reflux.

CONCLUSIONS

Prescription of proton pump inhibitors for objectively determined GERD should have time limits, as prolonged treatment can result in prolonged esophageal bolus clearance time without relieving symptoms.

The Irritable Infant in the Neonatal Intensive Care Unit: Risk Factors and Biomarkers of Gastroesophageal Reflux Disease

OBJECTIVES

To determine risk factors for arching/irritability in high-risk infants and examine the significance of comorbidity and gastroesophageal reflux (GER) characteristics.

STUDY DESIGN

Retrospective analysis of 24-hour pH-impedance studies of symptomatic infants in a neonatal intensive care unit (ICU) (n = 516, 30.1 ± 4.5 weeks of gestation, evaluated at 41.7 ± 3.2 weeks postmenstrual age) was conducted. Comparisons were made between infants with >72 vs ≤72 arching/irritability events per day. We characterized risk factors for arching/irritability along with clinical, pH-impedance, and outcome correlates.

RESULTS

Of 39 973 arching/irritability events and 42 155 GER events, the averages per day were 77.6 ± 41.0 and 81.7 ± 48.2, respectively. Acid reflux and impedance bolus characteristics were not significantly different between infants with >72 and ≤72 arching/irritability events (P ≥ .05). The odds ratios (ORs) and 95% confidence intervals (CIs) adjusted for postmenstrual age and weight at evaluation were significant for risk factors of preterm birth (2.3 [1.2-4.4]), moderate or severe neuropathology (2.0 [1.1-3.6]), and presence of oral feeding at testing (1.57 [1.07-2.30]).

CONCLUSIONS

Acid GER disease is unlikely the primary cause of arching/irritability and empiric treatment should not be used when arching/irritability is present. Prematurity and neurologic impairment may be more likely the cause of the arching/irritability. Arching/irritability may not be a concern in orally fed infants.

A decade of evidence: standardized feeding initiative targeting feeding milestones and predicting NICU stays in premature infants in an all-referral level IV NICU

OBJECTIVE

Ten-year data from the simplified, individualized, milestone-targeted, pragmatic, longitudinal and educational (SIMPLE) feeding initiative were examined by gestational age (GA) category to characterize the feeding milestones, length of hospital stays (LOHS), annual variability and predictive models for LOHS.

STUDY DESIGN

Preterm infants (≤32 weeks GA, N = 434) in level-IV NICU had milestone-targeted feeding plans. Continuous data were analyzed for outcomes.

RESULTS

Over 93% successfully attained full oral feedings. Earlier acquisition of feeding milestones correlated with earlier discharge (P < 0.05). Year-wise analysis showed sustained maintenance of milestones (P < 0.05). Milestones and outcomes (P < 0.001) were significantly correlated with different GA categories. Prediction models for LOHS were derived using GA, BPD, age at full enteral, postmenstrual age (PMA) at 1st and full oral feeds.

CONCLUSIONS

The SIMPLE feeding program minimized variability and promoted acquisition of feeding milestones consistently. LOHS is predictable using feeding milestones, co-morbidities, GA, and PMA at feeding milestones.

Pharyngeal biorhythms during oral milk challenge in high-risk infants: Do they predict chronic tube feeding?

BACKGROUND

Eating difficulties are common in high-risk neonatal intensive care unit (NICU) infants; mechanisms remain unclear. Crib-side pharyngo-esophageal motility testing is utilized to assess contiguous swallowing physiology, and cross-system interplay with cardio-respiratory rhythms. Aims were to: (1) identify whether distinct pharyngeal rhythms exist during oral milk challenge (OMC), and (2) develop a chronic tube feeding risk prediction model in high-risk infants.

METHODS

Symptomatic NICU infants (N = 56, 29.7 ± 3.7 weeks birth gestation) underwent pharyngo-esophageal manometry with OMC at 40.9 ± 2.5 weeks postmenstrual age (PMA). Exploratory cluster data analysis (partitioning around k-medoids) was performed to identify patient groups using pharyngeal contractile rhythm data (solitary swallows and swallows within bursts). Subsequently, (a) pharyngeal-esophageal, cardio-respiratory, and eating method characteristics were compared among patient groups using linear mixed models, and (b) chronic tube feeding prediction model was created using linear regression.

RESULTS

Three distinct patient groups were identified with validity score of 0.6, and termed sparse (high frequency of solitary swallows), intermediate, or robust (high swallow rate within bursts). Robust group infants had: lesser pharyngeal and esophageal variability, greater deglutition apnea, pharyngeal activity, and esophageal activity (all p < 0.05), but less frequent heart rate decreases (p < 0.05) with improved clinical outcomes (milk transfer rate, p < 0.001, and independent oral feeding at discharge, p < 0.03). Chronic tube feeding risk = -11.37 + (0.22 × PMA) + (-0.73 × bronchopulmonary dysplasia) + (1.46 × intermediate group) + (2.57 × sparse group).

CONCLUSIONS

Robust pharyngeal rhythm may be an ideal neurosensorimotor biomarker of independent oral feeding. Differential maturation of cranial nerve-mediated excitatory and inhibitory components involving foregut, airway, and cardiac rhythms distinguishes the physiologic and pathophysiologic basis of swallowing and cardio-respiratory adaptation.

Symptom Scores and pH-Impedance: Secondary Analysis of a Randomized Controlled Trial in Infants Treated for Gastroesophageal Reflux

BACKGROUND AND AIMS

To evaluate and compare gastro-esophageal reflux (GER) symptom scores with pH-impedance and test the effects of acid-suppressive medications with or without feeding modifications on pH-impedance in high-risk infants.

METHODS

Infant Gastroesophageal Reflux Questionnaire Revised (I-GERQ-R) and 24-hour pH-impedance data were analyzed from 94 infants evaluated in a tertiary care setting for GER disease. Longitudinal data from 40 infants that received randomized GER therapy (proton pump inhibitor [PPI] with or without feeding modifications) for 4 weeks followed by 1-week washout were analyzed. Relationships between I-GERQ-R and pH-impedance metrics (acid reflux index, acid and bolus GER events, distal baseline impedance, and symptoms) were examined and effects of treatments compared.

RESULTS

(A) Correlations between I-GERQ-R and pH-impedance metrics were weak. (B) I-GERQ-R sensitivity, specificity, and positive predictive values were suboptimal when correlated with pH-impedance metrics. I-GERQ-R negative predictive value (NPV) was high for acid symptom-association probability (NPV = 84%) and distal baseline impedence (NPV = 86%) thresholds. (C) PPI with feeding modifications (vs PPI alone) did not alter pH-impedance metrics or symptom scores (P > .05); however, bolus clearance metrics worsened for both treatment groups (P < .05).

CONCLUSIONS

In high-risk infants (1) I-GERQ-R may be a helpful clinical screening tool to exclude acid-GER disease diagnosis and minimize unnecessary acid-suppressive treatment, but further testing is needed for diagnosis. (2) Acid-suppressive therapy with feeding modifications has no effect on symptom scores or pH-impedance metrics. Clearance of refluxate worsened despite PPI therapy, which may signal development of pharyngoesophageal dysmotility and persistence of symptoms. (3) Placebo-controlled trials are needed in high-risk infants with objective pH-impedance criteria to determine efficacy, safety, and underlying mechanisms. Clinicaltrials.gov ID: NCT02486263.

Evidence-Based Approaches to Successful Oral Feeding in Infants with Feeding Difficulties

Infants in the neonatal intensive care unit (NICU) frequently have feeding difficulties with the root cause remaining elusive to identify. Evaluation of the provider/parent/infant feeding process may provide objective clues to sources of feeding difficulty. Specialized testing may be necessary to determine if the infant's swallowing skills are dysfunctional, immature, or maldeveloped, and to determine the risk of feeding failure or chronic tube feeding. Current evidence-based diagnostic and management approaches resulting in successful oral feeding in the NICU infant are discussed.

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.

Predictive factors for fundoplication following esophageal atresia repair

BACKGROUND

One of the most frequent complications after repair of esophageal atresia (EA) is gastroesophageal reflux disease (GERD). Although GERD-associated EA is known to often require anti-reflux surgery, the predicting factors remain unclear. We retrospectively analyzed EA in our institution.

METHODS

Of 65 children with EA treated in our hospital from 1995 to 2018, 45 with Gross C type EA, followed for over 1 year, were enrolled in this study. The patients were divided into fundoplication and non-fundoplication groups and compared in terms of their clinical features.

RESULTS

The fundoplication and non-fundoplication groups included 13 and 32 cases, respectively. On univariate analysis, gestational age, body weight, prenatal diagnosis, polyhydramnios, re-do surgery, and gap length of the esophagus differed significantly between the groups (P < 0.05).

CONCLUSION

Early delivery, low body weight, and a long gap length are, are considered to be risk factors for fundoplication. However, the present study further showed that prenatal diagnosis and polyhydramnios were also significant contributing factors. The presence of a prenatal diagnosis and polyhydramnios may induce preterm delivery, therefore, cases of polyhydramnios due to suspected EA should be managed to prevent early delivery. Better understanding of the postnatal course after surgery is required, especially for prenatal diagnosis cases.

Pharyngoesophageal motility reflex mechanisms in the human neonate: importance of integrative cross-systems physiology

Swallowing is a critical function for survival and development in human neonates and requires cross-system coordination between neurological, airway, and digestive motility systems. Development of pharyngoesophageal motility is influenced by intra- and extrauterine development, pregnancy complications, and neonatal comorbidities. The primary role of these motility reflex mechanisms is to maintain aerodigestive homeostasis under basal and adaptive biological conditions including oral feeding, gastroesophageal reflux, and sleep. Failure may result in feeding difficulties, airway compromise, dysphagia, aspiration syndromes, and chronic eating difficulties requiring prolonged tube feeding. We review the integration of cross-systems physiology to describe the basis for physiological and pathophysiological neonatal aerodigestive functions.

Characterization of Esophageal and Sphincter Reflexes across Maturation in Dysphagic Infants with Oral Feeding Success vs Infants requiring Gastrostomy

To test the hypothesis that esophageal and sphincteric sensory-motor reflexes are distinct across maturation in infants with dysphagia receiving gastrostomy-tube (G-tube). This is a retrospective review of 29 dysphagic infants (N = 15 study requiring gastrostomy, N = 14 age matched control achieving oral feeds) that underwent longitudinal pharyngeal-esophageal manometry at 42.3 (37-50.2) weeks postmenstrual age (PMA) and 48.9 (43.3-57.9) weeks PMA. Graded stimuli (0.1-5 mL) of varying media (air, water, and apple juice) tested esophageal peristaltic reflex, upper esophageal sphincter contractile reflex (UESCR), and lower esophageal sphincter relaxation reflex (LESRR). Comparisons were performed between study and controls and across maturation (time-1 vs time-2). Data represented as mean ± SE or OR (95% CI). Across maturation (time-1 vs time-2): Study infants did not exhibit significant differences across in peristaltic, UES, or LES reflexes (all p > 0.05). In contrast, controls exhibited increased UES resting pressure (13 ± 3 vs 17 ± 3 mmHg, p = 0.001), LES resting pressure (22 ± 3 vs 25 ± 3 mmHg, p < 0.009), LES nadir pressure (0.5 ± 1 vs 4.3 ± 1 mmHg, p = 0.001), and esophago-deglutition responses [2.5 (1.23-4.88), p = 0.04], and decreased secondary peristalsis [0.44 (0.31-0.61), p = 0.001], UESCR [0.4 (0.25-0.65), p = 0.001], LESRR [0.4 (0.24-0.75), p = 0.01], and symptoms [0.6 (0.45-0.83), p = 0.005]. Among infants with dysphagia, esophageal provocation induced peristaltic reflex, UESCR, and LESRR advance with longitudinal maturation when infants are oral-fed successfully, but not in those who received gastrostomy. Underlying mechanisms may be related to esophageal sensitivity, afferent or efferent transmission, and coordination of upstream excitation and downstream inhibition, which can be potential therapeutic targets for improving feeding capabilities after gastrostomy placement in infants with dysphagia.

Differentiating esophageal sensitivity phenotypes using pH-impedance in intensive care unit infants referred for gastroesophageal reflux symptoms

BACKGROUND

To identify esophageal sensitivity phenotypes relative to acid (S_Acid), bolus (S_Bolus), acid and bolus (S_Acid+Bolus), and none (S_None) exposures in infants suspected with gastroesophageal reflux disease (GERD).

METHODS

Symptomatic infants (N = 279) were evaluated for GERD at 42 (40-45) weeks postmenstrual age using 24-h pH-impedance. Symptom-associated probability (SAP) for acid and bolus components defined esophageal sensitivity: (1) S_Acid as SAP ≥ 95% for acid (pH < 4), (2) S_Bolus as SAP ≥ 95% for bolus, (3) S_Acid+Bolus as SAP ≥ 95% for acid and bolus, or (4) S_None as SAP < 95% for acid and bolus.

RESULTS

Esophageal sensitivity prevalence (S_Acid, S_Bolus, S_Acid+Bolus, S_None) was 28 (10%), 94 (34%), 65 (23%), and 92 (33%), respectively. Emesis occurred more in S_Bolus and S_Acid+Bolus vs S_None (p < 0.05). Magnitude (#/day) of cough and emesis events increased with S_Bolus and S_Acid+Bolus vs S_None (p < 0.05). S_Acid+Bolus had increased acid exposure vs S_None (p < 0.05). Distributions of feeding and breathing methods were distinct in infants with S_Bolus vs S_None (both, p < 0.05). Multivariate analysis revealed that arching and irritability events/day were lesser at higher PMAs (p < 0.001) and greater for infants on NCPAP (p < 0.01) with S_Bolus and S_Acid+Bolus (p < 0.05). Coughs/day was greater at higher PMAs (p < 0.001) for infants with gavage and transitional feeding methods (p < 0.02) with S_Bolus and S_Acid+Bolus (p < 0.05) but lesser with Trach (p < 0.001). Number of emesis events/day were greater with S_Bolus and S_Acid+Bolus (p < 0.001). Sneezes/day decreased for infants on Trach (p = 0.02).

CONCLUSIONS

Feeding and breathing methods can influence the frequency and type of aerodigestive symptoms. We differentiated esophageal sensitivity phenotypes in NICU infants referred for GERD symptoms using pH-impedance. Acid sensitivity alone was rare, which may explain poor response to acid suppressives; aerodigestive symptoms were predominantly linked with bolus spread. Magnitude of esophageal acid exposure and esophageal sensitivity to bolus spread may explain the pathophysiological basis for symptoms.

IMPACT

Objective GERD diagnosis and reasons for symptoms in NICU infants remains unclear. Differentiation of esophageal sensitivities by acid and bolus components of GER reveal distinct symptom profiles, specifically the bolus component of GER significantly contributes to symptom occurrence. Acid only sensitivity to GER is rare, and acid-suppressive therapy alone may not improve symptoms in a majority of NICU infants. Magnitude of esophageal acid exposure and esophageal sensitivity to any bolus spread may explain the pathophysiological basis for symptoms. Feeding and breathing methods can influence the frequency and type of aerodigestive symptoms. GERD treatments should be individualized to the patient's GERD phenotype and likely also target the bolus component of GER.

Acid Suppression Use Among Infants in One Tertiary Children's Hospital in China, 2015-2018: A Retrospective Observational Study

Clinical guidelines emphasized that physicians should be cautious when prescribing acid suppressions to infants. Histamine-2 receptor antagonists (H2RAs) and proton pump inhibitors (PPIs) are not approved for use in infants aged below 2 years in China. We investigated H2RA/PPI use in infants aged below 2 years hospitalized between 1st January 2015 and 31st December 2018 in a Chinese tertiary children's hospital. Our study observed that H2RAs/PPIs were frequently prescribed with a prevalence of 4.4% (7,158/162,192). The frequency of PPI use was over two-fold than that of H2RA use (71.9%, 5,148/7,158; 28.1%, 2,011/7,158). H2RAs/PPIs were commonly used to treat infants without digestive system diseases (57.5%, 4,118/7,158). Further studies are urgently needed to evaluate the effectiveness and safety of H2RAs/PPIs in infants.

Impact of Feeding Strategies With Acid Suppression on Esophageal Reflexes in Human Neonates With Gastroesophageal Reflux Disease: A Single-Blinded Randomized Clinical Trial

INTRODUCTION

Aims were to test hypothesis that esophageal provocation-induced reflexes are superior with acid suppression plus feeding modifications vs acid suppression alone among infants treated for gastroesophageal reflux disease (GERD).

METHODS

Infants (N = 49, 41.3 ± 2.6 of postmenstrual age) with acid reflux index >3% underwent longitudinal motility testing (weeks 0 and 5) with graded midesophageal provocation to test randomly allocated therapies (4 weeks' proton pump inhibitor [PPI] ± feeding modifications) on sensory-motor aerodigestive reflexes. Feeding modification included restricted fluid volume <140 mL/kg per day, fed over 30 minutes in right lateral position and supine postprandial position. Primary motility outcome was frequency-occurrence of peristaltic reflex. Secondary outcomes included upper esophageal sphincter contractile reflex, lower esophageal sphincter (LES) relaxation reflex, respiratory change, and symptom characteristics.

RESULTS

Treatment groups did not differ for primary outcome (odds ratio = 0.8, 95% confidence interval 0.4-1.6, P = 0.99) or secondary outcomes (all P > 0.05). For both treatment groups at follow-up, distal esophageal contraction and LES tone decreased, and LES relaxation reflex occurrence is less frequent (all P < 0.05). In a subgroup analysis, comparing infants with PPI washout (N = 40) vs with continued (N = 9) PPI therapy, no differences were noted for aerodigestive reflex response frequency-occurrence (all P > 0.05).

DISCUSSION

In infants with GERD, feeding modification with acid suppression is not superior to acid suppression alone in modifying aerodigestive reflexes (frequency, sensation, or magnitude). Contiguous areas targeted by GER, i.e., LES and distal esophageal functions, worsened at follow-up for both groups despite PPI therapy. Maturation is likely the key factor for GERD resolution in infants, justifying the use of placebo in clinical trials for objectively determined GERD.

The Emerging Importance of High-Resolution Manometry in the Evaluation and Treatment of Deglutition in Infants, Children, and Adults: New Opportunities for Speech-Language Pathologists

Purpose Diagnostic precision and prolonged testing before, during, and after deglutition is lacking across the age spectrum. Conventional clinical evaluation and radiologic methods are widely used but are reliant on human perception, carrying the risk of subjectivity. High-resolution manometry (HRM) is an emerging clinical and research tool and has the capability to objectively measure the dynamics, kinetics, regulatory, and correlation aspects of deglutition. Method We review the basics of manometry and the methods, metrics, and applications of this technology across the age spectrum. The goal is to aid in the translation of HRM from research tool to clinical use by the speech-language pathologist in the development of better global plans to understand normal and abnormal deglutition. Results HRM is an easily adaptable precise diagnostic tool that can be used to examine deglutition phases and abnormalities across the age spectrum from neonates to nonagenarians and can be a valuable adjunct to specialty evaluation of persistent deglutition disorders. Conclusion New opportunities will emerge upon further research for larger-scale translation once normative data and recognition of biomarkers of abnormality are ascertained.

Approach to Feeding Difficulties in Neonates and Infants: A Comprehensive Overview

Deglutition disorders (DD) can be transient and considered as physiologic during normal maturation. However, when oral feeding milestones are impaired and bothersome symptoms and aerodigestive consequences are associated, it is interpreted as DD with varying specific entities, such as feeding difficulties, swallowing disorders, aerodigestive illness, and aspiration syndromes. Symptoms related to DD are heterogeneous and managed empirically. This article clarifies current controversies, explains the potential role of safe feeding and physiologic and pathophysiologic perspectives, and highlights current advances in the field. Evidence basis for diagnostic strategies is discussed, and involves evaluation for structure and function tests, and nutrition and feeding assessment.

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.

Mechanisms of Aerodigestive Symptoms in Infants with Varying Acid Reflux Index Determined by Esophageal Manometry

OBJECTIVE

To test whether symptom generation in infants is related to the severity of gastroesophageal reflux disease (GERD) symptoms as determined by the Acid Reflux Index (ARI), stimulus media, and stimulus volume during provocative esophageal manometry.

STUDY DESIGN

Symptomatic neonates (n = 74) born at a median of 28.9 weeks gestation (range, 23.4-39.4 weeks) were studied at a median of 41.0 weeks (range, 34.6-48.0 weeks) postmenstrual age using 24-hour pH-impedance methods to determine ARI severity, followed by provocative esophageal manometry with graded mid-esophageal infusions (0.1-5.0 mL) of air, water, and apple juice. Peristaltic reflexes and symptom characteristics were compared among ARI severity categories using linear mixed models and generalized estimating equations.

RESULTS

The effects of 2635 separate esophageal stimuli on reflexes and symptoms were analyzed. Peristaltic reflexes occurred in 1880 infusions (71%), and physical, cardiorespiratory, sensory symptoms were seen in 439 infusions (17%). Symptom prevalence did not differ across the ARI severity categories (ARI <3, 18%; ARI 3-7, 17%; ARI >7, 16%; P = 1.0). Symptom and peristaltic responses increased with incremental stimulus volumes (all media, P < .001).

CONCLUSIONS

Symptoms and peristaltic reflexes are manifestations of the recruitment of several neurosensory and neuromotor pathways evoked by mid-esophageal infusions. ARI severity grade plays no role in symptom generation, indicating that GERD should not be diagnosed and severity should not be assigned based on symptoms alone. An increase in symptom occurrence was noted with increasing stimulus volumes, which provided increased activation of receptors, afferents, and efferents in evoking peristaltic clearance reflexes.

Pharyngoesophageal and cardiorespiratory interactions: potential implications for premature infants at risk of clinically significant cardiorespiratory events

The aims of this study were to 1) examine pharyngoesophageal and cardiorespiratory responses to provoking pharyngeal stimuli, and 2) to determine potential contributory factors impacting heart rate (HR) changes to provide insight into cardiorespiratory events occurring in preterm infants. Forty-eight neonates (19 females and 29 males, born at 27.7 ± 0.5 wk; mean ± SE) pending discharge on full oral feeds were studied at 38.7 ± 0.2 wk postmenstrual age using concurrent pharyngoesophageal manometry, electrocardiography, respiratory inductance plethysmography, and nasal airflow thermistor. Pharyngoesophageal and cardiorespiratory responses (prevalence, latency, and duration) were quantified upon abrupt pharyngeal water stimuli (0.1, 0.3, and 0.5 ml in triplicate). Mixed linear models and generalized estimating equations were used for comparisons between HR changes. Contributory factors included stimulus characteristics and subject characteristics. Of 338 pharyngeal stimuli administered, HR increased in 23 (7%), decreased in 108 (32%), and remained stable in 207 (61%) neonates. HR decrease resulted in repetitive swallowing, increased respiratory-rhythm disturbance, and decreased esophageal propagation rates (all, P < 0.05). HR responses were related to stimulus volume, stimulus flow rate, and extreme prematurity (all, P < 0.05). In preterm infants, HR remains stable in a majority of pharyngeal provocations. HR decrease, due to pharyngeal stimulation, is related to aberrant pharyngoesophageal motility and respiratory dysregulation and is magnified by prematurity. We infer that the observed aberrant responses across digestive, respiratory, and cardiovascular systems are related to maladaptive maturation of the parasympathetic nervous system. These aberrant responses may provide diagnostic clues for risk stratification of infants with troublesome cardiorespiratory events and swallowing difficulty. NEW & NOTEWORTHY Cardiorespiratory rhythms concurrent with pharyngeal, upper esophageal sphincter, and esophageal body responses were examined upon pharyngeal provocation in preterm-born infants who were studied at full-term maturation. Decreased heart rate (HR) was associated with extreme preterm birth and stimulus flow/volume. With HR decrease responses, aerodigestive reflex abnormalities were present, characterized by prolonged respiratory rhythm disturbance, repetitive multiple swallowing, and poor esophageal propagation. Promoting esophageal peristalsis may be a potential therapeutic target.

Defining pharyngeal contractile integral during high-resolution manometry in neonates: a neuromotor marker of pharyngeal vigor

BACKGROUND

Pharyngeal contractility is critical for safe bolus propulsion. Pharyngeal contractile vigor can be measured by Pharyngeal Contractile Integral (PhCI): product of mean pharyngeal contractile amplitude, length, and duration. We characterized PhCI in neonates and examined the hypothesis that PhCI differs with mode of stimulation.

METHODS

Nineteen neonates born at 38.6 (34-41) weeks gestation were evaluated at 42.9 (40.4-44.0) weeks postmenstrual age using high-resolution manometry (HRM). PhCI was calculated using: (a) Conventional and (b) Automated Swallow Detection algorithm (ASDA) methods. Contractility metrics of all pharyngeal regions were examined using mixed statistical models during spontaneous and adaptive state (pharyngeal and oral stimulus) swallowing.

RESULTS

PhCI of oral stimuli swallows were distinct from pharyngeal stimuli and spontaneous swallows (P < 0.05). Correlation between conventional and ASDA methods was high (P < 0.001). PhCI increased with swallows for pharyngeal stimulation (P < 0.05) but remained stable for swallows with oral stimulation. PhCI differed between proximal and distal pharynx (P < 0.001).

CONCLUSIONS

PhCI is a novel reliable metric capable of distinguishing (1) proximal and distal pharyngeal activity, (2) effects of oral and pharyngeal stimulation, and (3) effects of prolonged stimulation. Changes in pharyngeal contractility with maturation, disease, and therapies can be examined with PhCI.

Older Age Reduces Upper Esophageal Sphincter and Esophageal Body Responses to Simulated Slow and Ultraslow Reflux Events and Post-Reflux Residue

BACKGROUND & AIMS

It is not clear how age affects airway protective mechanisms. We investigated the effects of aging on upper esophageal sphincter (UES) and esophageal body pressure responses to slow and ultraslow simulated reflux events and post-reflux residue.

METHODS

We performed a prospective study of 11 elderly (74 ± 9 years old) and 11 young (28 ± 7 years old) healthy volunteers. Participants were placed in a supine position and evaluated by concurrent high-resolution impedance manometry and an esophageal infusion technique. Potential conditions of gastroesophageal reflux were simulated, via infusion of 0.1 N HCl and saline. UES and esophageal pressure responses were measured during the following: slow infusion (1 mL/s) for 60 seconds, 60 seconds of postinfusion dwell period, ultraslow infusion (0.05 mL/s) for 60 seconds, and 60 seconds of a postinfusion dwell period. All infusions were repeated 3 times. We used the UES high-pressure zone contractile integral (UES-CI) to determine responses of the UES.

RESULTS

Young and elderly subjects each had a significant increase in the UES-CI during slow infusions and during entire passive dwell intervals compared with baseline (P < .01, both groups). Ultraslow infusions were associated with a significant increase in UES-CI in only the young group, in the late infusion period, and into the dwell interval (P < .01). During the slow infusions and their associated dwell periods, young subjects had a higher frequency of secondary peristalsis than elderly subjects (P < .05). There was more secondary peristalsis during active infusions than dwell intervals. Secondary peristalsis was scarce during ultraslow infusions in both groups.

CONCLUSIONS

UES and esophageal body pressure responses to low-volume ultraslow reflux and associated post-reflux residue are reduced in elderly individuals. This deterioration could have negative effects on airway protection for people in this age group.

Effect of right lateral position with head elevation on tracheal aspirate pepsin in ventilated preterm neonates: randomized controlled trial

Objective: To evaluate the effect of right lateral positioning in comparison with supine positioning on tracheal aspirate pepsin levels as a marker of aspiration of gastric contents in ventilated preterm neonates. Study design: This randomized controlled trial was conducted on 60 ventilated preterm neonates <35 weeks; 30 neonates were nursed in right lateral position for 6 hours while the other 30 neonates were nursed in supine position for 6 hours. Tracheal aspirate sample was obtained from each neonate in both the groups just after the end of 6 hours and pepsin level was measured. Results: Neonates in right lateral position group had significantly lower tracheal pepsin level than neonates in supine position group (6 ng/ml) interquartile range [IQR] (3-20) versus 15 ng/ml [IQR] (5.5-90) (p = .024). There is positive correlation between tracheal aspirate pepsin level and fraction of inspired oxygen (FiO₂) needed during the intervention (r = 0.383, p = .040). There is no correlation between tracheal pepsin level and gestational age, birth weight, or duration of mechanical ventilation and other ventilatory settings. Conclusion: Nursing ventilated premature infants in right lateral position is associated with decreased aspiration of gastric contents.

Cardiorespiratory events in infants with gastroesophageal reflux symptoms: Is there any association?

BACKGROUND

Cardiorespiratory (CR) events (apnea, bradycardia, oxygen desaturation) and gastroesophageal reflux (GER) symptoms often coexist in infants admitted to Neonatal Intensive Care Unit, leading to over-prescription of drugs and delayed discharge. We aimed to evaluate the relationships between CR and GER events.

METHODS

The temporal associations between CR and GER events were analyzed in symptomatic infants who underwent synchronized CR and pH-impedance monitoring. The symptom association probability (SAP) index was used to identify infants with a significant number of temporal associations. Gastroesophageal reflux characteristics and the chronological sequence of CR and GER events occurring within 30 seconds of each other were evaluated according to SAP index.

KEY RESULTS

Of the 66 infants enrolled, aged 29 (18-45) days, 58 had CR events during monitoring. From these 58 patients, a total of 1331 CR events and 5239 GER (24% acidic) were detected. The SAP index was positive in seven (12%) infants. These infants had greater GER frequency, duration, and proximal extent (P < .05). The number of temporal associations was 10 times greater in the positive SAP group. Gastroesophageal reflux events preceded CR events in 83% of these associations. These GER events had a higher proximal extent (P = .004), but showed no differences in pH values.

CONCLUSIONS & INFERENCES

The simultaneous evaluation of CR and GER events could be useful to identify infants with severe GER and significant temporal associations between these events. Treatment of GER could be indicated in these infants, but as the GER events involved are mainly non-acidic, empirical treatment with antacids is, often, inappropriate.

The effect of body position on esophageal reflexes in cats: a possible mechanism of SIDS?

BackgroundIt has been hypothesized that life-threatening events are caused by supraesophageal reflux (SER) of gastric contents that activates laryngeal chemoreflex-stimulated apnea. Placing infants supine decreases the risk of sudden infant death syndrome (SIDS). The aim of this study was to determine whether body position affects esophageal reflexes that control SER.MethodsWe instrumented the pharyngeal and esophageal muscles of decerebrate cats (N=14) to record EMG or manometry, and investigated the effects of body position on the esophago-upper esophageal sphincter (UES) contractile reflex (EUCR), esophago-UES relaxation reflex (EURR), esophagus-stimulated pharyngeal swallow response (EPSR), secondary peristalsis (SP), and pharyngeal swallow (PS). EPSR, EUCR, and SP were activated by balloon distension, EURR by air pulse, and PS by nasopharyngeal water injection. The esophagus was stimulated in the cervical, proximal thoracic, and distal thoracic regions. The threshold stimulus for activation of EUCR, EURR, and PS, and the chance of activation of EPSR and SP were quantified.ResultsWe found that only EPSR was significantly more sensitive in the supine vs. prone position regardless of the stimulus or the position of the stimulus in the esophagus.ConclusionWe hypothesize that the EPSR may contribute to the protection of infants from SIDS by placement in the supine position.

Development of an oesophageal stimulation method to elicit swallowing reflex in humans

Swallowing reflex is known to be evoked by gastroesophageal regurgitation or oesophageal stimulation in animal studies. However, details regarding the stimulating material, bolus size and stimulation area remain unclear for the stimulation-induced type of swallowing reflex in humans. Here, we evaluated the effects of different kinds of stimulation via water and air injection of the oesophagus on the initiation of the swallowing reflex. Nine healthy individuals participated in this study. A fibre-optic endoscope was passed transnasally, and a thin catheter for injection was passed through the other side. The tip of the catheter was placed at the upper, upper middle, lower middle or lower region of the oesophagus, and the rate of injection was controlled at 0.2 mL/s. Swallowing reflex latency was calculated as the time from injection via air or thin/thick fluid until the onset of white-out in endoscopic images. Reflex latency was significantly shorter when injection occurred at the upper region of the oesophagus than at the lower region, for both thin and thick fluids (P < .01). At the upper region of the oesophagus, the latency was significantly shorter after injection of thin fluid than with thick fluid (P < .05). Injection of air did not induce the swallowing reflex at all sites. These findings suggest that while the swallowing reflex is evoked by stimulation via fluid injection of the oesophagus in humans, sensitivity is greatest in the upper region of the oesophagus compared with the lower region and can vary depending on the injecting material.

Reflex cardiorespiratory events from esophageal origin are heightened by preterm birth

The involvement of gastroesophageal refluxes in cardiorespiratory events of preterm infants remains controversial. While a few studies in full-term newborn animals have shown that stimulation of esophageal receptors leads to cardiorespiratory reflexes, the latter remain largely unknown, especially after premature birth. The present study aimed to 1) characterize the cardiorespiratory reflexes originating from esophageal receptors in newborn lambs and 2) test the hypotheses that preterm birth enhances reflex cardiorespiratory inhibition and that C-fibers are involved in these reflexes. Eight full-term lambs and 10 lambs born 14 days prematurely were studied. Following surgical instrumentation, a 6-h polysomnography was performed without sedation to record electrocardiogram, respiratory movements, arterial pressure, laryngeal constrictor muscle activity, state of alertness, and hemoglobin oxygen saturation. Five esophageal stimulations of the upper and/or lower esophagus, including rapid balloon inflation and/or HCl injection, were performed in random order. A second recording was performed in full-term lambs 24 h later, after C-fiber blockade by capsaicin. Results confirmed that esophageal stimulations induced inhibitory cardiorespiratory reflexes combined with protective mechanisms, including laryngeal closure, swallowing, coughing, increased arterial pressure, and arousal. Preterm birth heightened cardiorespiratory inhibition. The strongest cardiorespiratory inhibition was observed following simultaneous stimulation of the lower and upper esophagus. Finally, cardiorespiratory inhibition was decreased after C-fiber blockade. In conclusion, esophageal stimulation induces inhibitory cardiorespiratory reflexes, which are partly mediated by C-fibers and more pronounced in preterm lambs. Clinical relevance of these findings requires further studies, especially in conditions associated with increased cardiorespiratory events, e.g., neonatal infection.NEW & NOTEWORTHY Preterm birth heightens the cardiorespiratory events triggered by esophageal stimulation. The most extensive cardiorespiratory events are induced by simultaneous stimulation of the proximal and distal esophagus.

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.

Feeding Methods at Discharge Predict Long-Term Feeding and Neurodevelopmental Outcomes in Preterm Infants Referred for Gastrostomy Evaluation

OBJECTIVE

To test the hypothesis that oral feeding at first neonatal intensive care unit discharge is associated with less neurodevelopmental impairment and better feeding milestones compared with discharge with a gastrostomy tube (G-tube).

STUDY DESIGN

We studied outcomes for a retrospective cohort of 194 neonates <37 weeks' gestation referred for evaluation and management of feeding difficulties between July 2006 and July 2012. Discharge milestones, length of hospitalization, and Bayley Scales of Infant Development-Third Edition scores at 18-24 months were examined. χ², Mann-Whitney U, or t tests and multivariable logistic regression models were used.

RESULTS

A total of 60% (n = 117) of infants were discharged on oral feedings; of these, 96% remained oral-fed at 1 year. The remaining 40% (n = 77) were discharged on G-tube feedings; of these, 31 (40%) remained G-tube dependent, 17 (22%) became oral-fed, and 29 (38%) were on oral and G-tube feedings at 1 year. Infants discharged on a G-tube had lower cognitive (P <.01), communication (P = .03), and motor (P <.01) composite scores. The presence of a G-tube, younger gestation, bronchopulmonary dysplasia, or intraventricular hemorrhage was associated significantly with neurodevelopmental delay.

CONCLUSIONS

For infants referred for feeding concerns, G-tube evaluations, and feeding management, the majority did not require a G-tube. Full oral feeding at first neonatal intensive care unit discharge was associated with superior feeding milestones and less long-term neurodevelopmental impairment, relative to full or partial G-tube feeding. Evaluation and feeding management before and after G-tube placement may improve long-term feeding and neurodevelopmental outcomes.

Advances with Neonatal Aerodigestive Science in the Pursuit of Safe Swallowing in Infants: Invited Review

Feeding, swallowing, and airway protection are three distinct entities. Feeding involves a process of sequential, neurosensory, and neuromotor interactions of reflexes and behaviors facilitating ingestion. Swallowing involves anterograde bolus movement during oral-, pharyngeal-, and esophageal phases of peristalsis into stomach. During these events, coordination with airway protection is vital for homeostasis in clearing any material away from airway vicinity. Neurological-airway-digestive inter-relationships are critical to the continuum of successful feeding patterns during infancy, either in health or disease. Neonatal feeding difficulties encompass a heterogeneous group of neurological, pulmonary, and aerodigestive disorders that present with multiple signs posing as clinical conundrums. Significant research breakthroughs permitted understanding of vagal neural pathways and functional aerodigestive connectivity involved in regulating swallowing and aerodigestive functions either directly or indirectly by influencing the supra-nuclear regulatory centers and peripheral effector organs. These neurosensory and neuromotor pathways are influenced by pathologies during perinatal events, prematurity, inflammatory states, and coexisting medical and surgical conditions. Approaches to clarify pathophysiologic mapping of aerodigestive interactions, as well as translating these discoveries into the development of personalized and simplified feeding strategies to advance child health are discussed in this review article.

Characterization and mechanisms of the pharyngeal swallow activated by stimulation of the esophagus

Stimulation of the esophagus activates the pharyngeal swallow response (EPSR) in human infants and animals. The aims of this study were to characterize the stimulus and response of the EPSR and to determine the function and mechanisms generating the EPSR. Studies were conducted in 46 decerebrate cats in which pharyngeal, laryngeal, and esophageal motility was monitored using EMG, strain gauges, or manometry. The esophagus was stimulated by balloon distension or luminal fluid infusion. We found that esophageal distension increased the chance of occurrence of the EPSR, but the delay was variable. The chance of occurrence of the EPSR was related to the position, magnitude, and length of the stimulus in the esophagus. The most effective stimulus was long, strong, and situated in the cervical esophagus. Acidification of the esophagus activated pharyngeal swallows and sensitized the receptors that activate the EPSR. The EPSR was blocked by local anesthesia applied to the esophageal lumen, and electrical stimulation of the recurrent laryngeal nerve caudal to the cricoid cartilage (RLNc) activated the pharyngeal swallow response. We conclude that the EPSR is activated in a probabilistic manner. The receptors mediating the EPSR are probably mucosal slowly adapting tension receptors. The sensory neural pathway includes the RLNc and superior laryngeal nerve. We hypothesize that, because the EPSR is observed in human infants and animals, but not human adults, activation of EPSR is related to the elevated position of the larynx. In this situation, the EPSR occurs rather than secondary peristalsis to prevent supraesophageal reflux when the esophageal bolus is in the proximal esophagus.

Neonatal Histamine-2 Receptor Antagonist and Proton Pump Inhibitor Treatment at United States Children's Hospitals

OBJECTIVE

To determine treatment frequency and duration of histamine-2 receptor antagonist (H2RA)/proton pump inhibitor (PPI) use among infants hospitalized within US children's hospital neonatal intensive care units and evaluate diagnoses/demographic factors associated with use.

STUDY DESIGN

We retrospectively analyzed a cohort of neonatal intensive care unit infants admitted to 43 US children's hospitals within the Pediatric Health Information System database between January 2006 and March 2013 to determine H2RA/PPI treatment frequency, timing/duration of treatment, factors associated with use, percent of infants remaining on treatment at discharge, and interhospital prescribing variation. We used a modified Poisson regression to calculate the adjusted probability of infants ever receiving H2RAs/PPIs in relation to diagnosis, gestation, and sex.

RESULTS

Of the 122 002 infants evaluated, 23.8% (n = 28 989) ever received an H2RA or PPI; 19.0% received H2RAs (n = 23 187), and 10.5% (n = 12 823) received PPIs. Extremely preterm infants and term infants were the most likely to receive H2RA and PPI treatment. Infants with gastroesophageal reflux disease (relative risk [RR] = 3.13) and congenital heart disease (RR = 2.41) had the highest H2RA/PPI treatment probabilities followed by those with an ear, nose, and throat diagnosis (RR = 2.34; P < .05). The majority of treated infants remained treated at discharge.

CONCLUSIONS

Despite limited evidence and increasing safety concerns, H2RAs/PPIs are frequently prescribed to extremely preterm neonates and those with congenital anomalies and continued through discharge. Our findings support the need for innovative studies to examine the comparative effectiveness and safety of H2RA/PPIs vs no treatment in these high-risk neonatal populations.

Effects of pacifier and taste on swallowing, esophageal motility, transit, and respiratory rhythm in human neonates

BACKGROUND

Pacifier use is widely prevalent globally despite hygienic concerns and uncertain mechanistic effects on swallowing or airway safety.

AIMS

The effects of pacifier and taste interventions on pharyngo-esophageal motility, bolus transit, and respiratory rhythms were investigated by determining the upper esophageal sphincter (UES), esophageal body, esophagogastric junction (EGJ) motor patterns and deglutition apnea, respiratory rhythm disturbances, and esophageal bolus clearance.

METHODS

Fifteen infants (six males; median gestation 31 weeks and birth weight 1.4 kg) underwent high-resolution impedance manometry at 43 (41-44) weeks postmenstrual age. Manometric, respiratory, and impedance characteristics of spontaneous swallows, pacifier-associated dry swallowing and taste (pacifier dipped in 3% sucrose)-associated swallowing were analyzed. Linear mixed and generalized estimating equation models were used. Data are presented as mean ± SEM, %, or median (IQR).

KEY RESULTS

Pharyngo-esophageal motility, respiratory, and impedance characteristics of 209 swallows were analyzed (85 spontaneous swallows, 63 pacifier- swallows, 61 taste- swallows). Basal UES and EGJ pressures decreased upon pacifier (p < 0.05) and taste interventions (p < 0.05); however, esophageal motility, respiratory rhythm, and impedance transit characteristics were similar with both interventions.

CONCLUSIONS & INFERENCES

Oral stimulus with pacifier or taste interventions decreases UES and EGJ basal pressure, but has no effects on pharyngo-esophageal motility, airway interactions, or esophageal bolus transit. A decrease in central parasympathetic-cholinergic excitatory drive is likely responsible for the basal effects.

Development of infant oral feeding skills: what do we know?

The hospital discharge of premature infants in neonatal intensive care units is often delayed due to their inability to feed by mouth safely and competently. With immature physiologic functions, infants born prematurely cannot be expected to readily feed by mouth at the equivalent age of a third trimester of gestation as the majority of their term counterparts do. Consequently, it is crucial that health care professionals gain an adequate knowledge of the development of preterm infants' oral feeding skills so as to optimize their safety and competency as they transition to oral feeding. With a greater sensitivity toward their immature skills, we can offer these infants a safer and smoother transition to independent oral feeding than is currently observed. This review article is an overview of the evidence-based research undertaken over the past 2 decades on the development of very-low-birth-weight infants' oral feeding skills. The description of the different functional levels where these infants can encounter hurdles may assist caregivers in identifying a potential cause or causes for their individual patients' oral feeding difficulties.

Dysphagia in the high-risk infant: potential factors and mechanisms

Neonatal dysphagia, or abnormalities of swallowing, represent a major global problem, and consequences of dysfunctional feeding patterns carry over into infancy and toddler age groups. Growth, development, and independent feeding skills are all delayed among high-risk infants. Such a group comprises premature birth, low-birth-weight, congenital anomalies, perinatal asphyxia, postsurgical, and sepsis categories. The conflict between pathophysiologic and pragmatic feeding strategies remains a major conundrum and is largely due to a lack of validated diagnostic approaches amid heterogeneity of the patient phenotype. Thus, well-tested feeding management strategies that can be generalizable are lacking. Furthermore, the aerodigestive symptoms and signs, potential risk factors, and contributory etiologies remain nonspecific. This article presents mechanistic evidence related to the pathophysiologic basis of neonatal dysphagia as well as potential opportunities to improve feeding abilities and long-term development.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Gestational and postnatal modulation of esophageal sphincter reflexes in human premature neonates

BACKGROUND

Effects of gestational age (GA) and postnatal maturation on upper and lower esophageal sphincter (UES and LES) reflex development remain unclear. We hypothesized very-preterm (VPT) born neonates (< 32 wk GA) have delayed maturation of UES contractile reflex (UESCR) and LES relaxation reflex (LESRR) vs. preterm (PT) born (32-37 wk GA) neonates.

METHODS

Using provocative manometry, effects of 1,263 graded mid-esophageal stimuli (air, liquid) on sensory-motor characteristics of UESCR and LESRR were investigated in 24 VPT-born and 12 PT-born neonates (37.8 ± 0.6 vs. 38.9 ± 0.4 wk postmenstrual age respectively, P = 0.14).

RESULTS

In response to liquid stimuli (vs. air), VPT-born neonates displayed prolonged UESCR and LESRR response latencies (P < 0.001) and prolonged UESCR and LESRR durations (P < 0.01); unlike PT-born neonates, who exhibit prolonged LESRR response latency (P < 0.01), but similar UESCR and LESRR durations (P = 0.2). Differences were noted in LESRR duration in VPT vs. PT neonates for air stimuli (P = 0.04). With liquid stimuli, increasing GA was associated with decreasing response onset latencies to UESCR and LESRR (P < 0.05), and increasing LESRR duration (P = 0.02).

CONCLUSION

Using GA as categorical or continuous variable, vagus-mediated mechano-sensitive and liquid-sensitive reflex characteristics of UESCR and LESRR are distinct; LESRR differs with varying intrauterine maturation suggesting inhibitory modulation progresses with advancing maturation.

Effects of birth asphyxia on the modulation of pharyngeal provocation-induced adaptive reflexes

Perinatal asphyxia and aerodigestive symptoms are troublesome. We tested the hypothesis that pharyngeal provocation alters proximal and distal aerodigestive reflex coordination and kinetics in infants with hypoxic ischemic encephalopathy (HIE), compared with healthy controls. Specifically, we characterized the sensory-motor properties of pharyngeal provocation-induced effects on upper esophageal sphincter (UES) and lower esophageal sphincter (LES) reflexes. Ten orally fed controls (32.0 ± 1.5 wk gestation) and 25 infants with HIE (38.1 ± 0.4 wk gestation) were evaluated at 39.7 ± 0.9 and 41.9 ± 0.6 wk postmenstrual age respectively. Pharyngo-esophageal reflexes evoked upon graded water stimuli were tested using water-perfusion micromanometry methods. Analysis included sensory-motor characteristics of pharyngeal reflexive swallow (PRS), pharyngo-UES-contractile reflex (PUCR), esophageal body-waveform kinetics, and pharyngo-LES-relaxation reflex (PLESRR). For controls vs. infants with HIE, median appearance, pulse, grimace, activity, respiration (APGAR) scores were 6 vs. 1 at 1 min (P < 0.001) and 8 vs. 3 at 5 min (P < 0.001). Upon pharyngeal- stimulation, HIE infants (vs. controls) had frequent PUCR (P = 0.01); increased UES basal tone (P = 0.03); decreased LES basal tone (P = 0.002); increased pharyngeal-waveforms per stimulus (P = 0.03); decreased frequency of LES relaxation (P = 0.003); and decreased proximal esophageal contractile amplitude (P = 0.002), with prolonged proximal esophageal contractile duration (P = 0.008). Increased tonicity and reactivity of the UES and dysregulation of LES may provide the pathophysiological basis for pooling of secretions, improper bolus clearance, and aspiration risk. Deficits in function at the nuclear or supranuclear level involving glossopharyngeal and vagal neural networks and respiratory regulatory pathways involved with aerodigestive protection may be contributory.

Mechanisms of cough provocation and cough resolution in neonates with bronchopulmonary dysplasia

BACKGROUND

Cough and deglutition are protective mechanisms that defend against aspiration. We identified mechanisms associated with cough provocation as well as those associated with cough resolution in infants with bronchopulmonary dysplasia (BPD).

METHODS

Manometry signatures of cough were recognized in 16 premature infants with BPD undergoing concurrent esophageal manometry, respiratory inductance plethysmography, and nasal air flow measurements. Pretussive and post-tussive pharyngo-esophageal motility changes were analyzed. Mechanisms associated with cough and mechanisms that restored respiratory and esophageal normalcy were analyzed.

RESULTS

We analyzed 312 cough events during 88 cough clusters; 97% were associated with recognizable manometric patterns. Initial mechanisms related with coughing included nonpropagating swallow (59%), upper esophageal sphincter (UES) reflex contraction (18%), and lower esophageal sphincter (LES) relaxation (14%). UES and LES dysfunction was present in 69% of nonpropagating swallow-associated cough clusters. Mechanisms restoring post-tussive normalcy included primary peristalsis (84%), secondary peristalsis (8%), and none recognized (8%). UES contraction reflex was associated with cough clusters more frequently in infants on nasal continuous positive airway pressure (NCPAP) (OR = 9.13, 95% CI = 1.88-44.24).

CONCLUSION

Cough clusters in infants with BPD had identifiable etiologies associated with esophageal events; common initial mechanisms were of upper aerodigestive origin, while common clearing mechanisms were peristaltic reflexes.

Upper and lower esophageal sphincter kinetics are modified during maturation: effect of pharyngeal stimulus in premature infants

BACKGROUND

We hypothesized that changes in proximal and distal esophageal sphincter kinetics evoked upon pharyngeal provocation undergo longitudinal maturation.

METHODS

Pharyngeal stimulation-induced reflexes were characterized using novel pharyngo-esophageal motility methods in 19 healthy premature neonates, studied at 34.7 ± 0.8 wk (time-1) and 39.3 ± 1.1 wk postmenstrual age (time-2). Graded volumes of air (290 infusions) and sterile water (172 infusions) were infused to define sensory-motor characteristics of upstream (pharyngeal reflexive swallow, PRS) and downstream (pharyngo-lower esophageal sphincter relaxation reflex, PLESRR) esophageal reflexes. Data displayed as mean ± SE.

RESULTS

Threshold volumes were similar with air and water for PRS and PLESRR at time-1 and time-2. Multiple PRS responses were noted with water stimulus and were different between the media (time-1 vs. air, P < 0.0001; time-2 vs. air, P = 0.0003). Dose-response relationships for water were significant (P < 0.01 for PRS and PLESRR time-1 and time-2), but not with air.

CONCLUSION

Significantly, the recruitment frequency of PRS and PLESRR increases with maturation, liquid is a superior medium for evoking such swallowing reflexes, and stimulus-response relationships for these reflexes are evident. These changes in aerodigestive protective reflexive activity may indicate differences in modulation of excitatory and inhibitory pathways during longitudinal postnatal maturation.

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.

Achieving optimal feeds for preterm babies, recommendations and realities in practice: nigerian perspective

Preterm deaths are responsible for the highest number of neonatal mortality in Nigeria. Preterm nutrition contributes significantly to overall outcome particularly as it relates to neurodevelopment. Recently, new guidelines for enteral feedings in premature infants were issued by the American Academy of Paediatrics and European Society of Pediatric Gastroenterology, Hepatology and Nutrition Committee on Nutrition. Nevertheless, in clinical practice it is often difficult to attain suggested intakes at all times. The situation is worse in Nigeria where there are no specific national guidelines and recommendations derived from local data targeting Preterms. There is a high possibility of significant potential cumulative nutritional deficits occurring in Nigerian preterms. The inevitable suboptimal intake contributes significantly to the incidence of neonatal diseases and outcome. This review describes practical ways of optimizing nutritional intake in these vulnerable neonates with reference to Nigerian situation. Understanding the preterm gut, initiation of parenteral nutrition, need for minimal enteral feeds, ensuring adequate macro and micronutrients intake and need for follow up are discussed. There are limitations to the practice of the recommended preterm nutrition in Nigerian settings, nevertheless the interventions like early commencement of minimal enteral feeds and preference for human breast milk should be practiced optimally. Hence, all health professionals should acknowledge that preterm nutrition may be an emergency and need to improve their knowledge on when and how to achieve optimal feeds in them. There is a dare need through both clinical practice as well as research, to reduce nutritional deficits in these vulnerable infants.

Neuromotor mechanisms of pharyngoesophageal motility in dysphagic infants with congenital heart disease

BACKGROUND

Aero-digestive morbidities are common in congenital heart disease infants, and the mechanisms are unclear. We hypothesized that adaptive pharyngoesophageal motility reflexes are different in surgical congenital heart disease infants (S-CHD) vs. nonsurgical congenital heart disease infants (CHD) and healthy controls.

METHODS

Abrupt pharyngeal provocation was performed with graded water infusions using purpose-built micromanometry. The data from 12 S-CHD were compared with data from 10 CHD and 12 controls. One hundred and ninety-seven water stimulations were examined for the frequency, latency, duration, and magnitude of pharyngo-upper esophageal sphincter contractile response (PUCR), pharyngeal reflexive swallow (PRS), esophageal body peristalsis, and lower esophageal sphincter (LES) relaxation characteristics. Mixed statistical models were applied.

RESULTS

Frequency distribution (%) of PUCR: PRS: none in S-CHD vs. CHD vs. controls, respectively, were 36:46:17 vs. 9:80:11 vs. 15:61:24 (P < 0.05). Response latency to the final esophageal body waveform (P = 0.01) and the response duration of esophageal body peristalsis (P = 0.04) were prolonged in S-CHD vs. controls but were similar to CHD (P = 0.22). Pharyngeal infusion-induced LES relaxation characteristics were similar in all three groups.

CONCLUSION

Abnormality in the recruitment of PUCR or PRS reflexes and esophageal body peristalsis in S-CHD implicate dysregulation in vagal cholinergic excitatory neuromotor responses.

Respiratory events in infants presenting with apparent life threatening events: is there an explanation from esophageal motility?

OBJECTIVE

To test the hypothesis that proximal aerodigestive clearance mechanisms mediated by pharyngoesophageal motility during spontaneous respiratory events (SREs) are distinct in infants with apparent life threatening events (ALTEs).

STUDY DESIGN

Twenty infants (10 with proven ALTE, 10 healthy controls) had pharyngoesophageal manometry to investigate motility changes concurrent with respiratory events detected by respiratory inductance plethysmography and nasal thermistor methods. We measured changes in resting upper esophageal and lower esophageal sphincter pressures, esophageal peristalsis characteristics, and gastroesophageal reflux. Statistical analysis included mixed models; data presented as mean±SD, median (range), or percentage.

RESULTS

Infants with ALTE (vs controls) had: (1) delays in restoring aerodigestive normalcy as indicated by more frequent (P=.03) and prolonged SREs (P<.01); (2) a lower magnitude of protective upper esophageal sphincter contractile reflexes (P=.01); (3) swallowing as the most frequent esophageal event associated with SREs (84%), with primary peristalsis as the most prominent aerodigestive clearance mechanism (64% vs 38%, P<.01); (4) a higher proportion of failed esophageal propagation (10% vs 0%, P=.02); and (5) more frequent mixed apneic mechanisms (P<.01) and more gasping breaths (P=.04).

CONCLUSIONS

In infants with ALTE, prolonged SREs are associated with ineffective esophageal motility characterized by frequent primary peristalsis and significant propagation failure, thus suggestive of dysfunctional regulation of swallow-respiratory junction interactions. Hence, treatment should not target gastroesophageal reflux, but rather the proximal aerodigestive tract.

Esophageal reflexes modulate frontoparietal response in neonates: Novel application of concurrent NIRS and provocative esophageal manometry

Central and peripheral neural regulation of swallowing and aerodigestive reflexes is unclear in human neonates. Functional near infrared spectroscopy (NIRS) is a noninvasive method to measure changes in oxyhemoglobin (HbO) and deoxyhemoglobin (HbD). Pharyngoesophageal manometry permits evaluation of aerodigestive reflexes. Modalities were combined to investigate feasibility and to test neonatal frontoparietal cortical changes during pharyngoesophageal (visceral) stimulation and/or swallowing. Ten neonates (45.6 ± 3.0 wk postmenstrual age, 4.1 ± 0.5 kg) underwent novel pharyngoesophageal manometry concurrent with NIRS. To examine esophagus-brain interactions, we analyzed cortical hemodynamic response (HDR) latency and durations during aerodigestive provocation and esophageal reflexes. Data are presented as means ± SE or percent. HDR rates were 8.84 times more likely with basal spontaneous deglutition compared with sham stimuli (P = 0.004). Of 182 visceral stimuli, 95% were analyzable for esophageal responses, 38% for HDR, and 36% for both. Of analyzable HDR (n = 70): 1) HbO concentration (μmol/l) baseline 1.5 ± 0.7 vs. 3.7 ± 0.7 poststimulus was significant (P = 0.02), 2) HbD concentration (μmol/l) between baseline 0.1 ± 0.4 vs. poststimulus -0.5 ± 0.4 was not significant (P = 0.73), and 3) hemispheric lateralization was 21% left only, 29% right only, and 50% bilateral. During concurrent esophageal and NIRS responses (n = 66): 1) peristaltic reflexes were present in 74% and HDR in 61% and 2) HDR was 4.75 times more likely with deglutition reflex vs. secondary peristaltic reflex (P = 0.016). Concurrent NIRS with visceral stimulation is feasible in neonates, and frontoparietal cortical activation is recognized. Deglutition contrasting with secondary peristalsis is related to cortical activation, thus implicating higher hierarchical aerodigestive protective functional neural networks.

Maturation of upstream and downstream esophageal reflexes in human premature neonates: the role of sleep and awake states

We tested the hypothesis that the sensory-motor characteristics of aerodigestive reflexes are dependent on stimulus type and volumes, sleep or awake states, and maturation. Thirteen neonates were studied at 33.6 ± 0.5 wk (time 1) and 37.3 ± 0.5 wk (time 2) postmenstrual age using multimodal provocative esophageal manometry concurrent with video polysomnography. Effects of graded volumes (399 infusions at time 1, 430 infusions at time 2) of midesophageal stimulation with air, water, and apple juice on the sensory thresholds and recruitment frequency of upper esophageal sphincter (UES), esophageal body, and lower esophageal sphincter (LES) reflexes were investigated during sleep and awake states. Sensory thresholds for aerodigestive reflexes between maturational stages were similar. Increased frequency recruitment of UES contractile reflex, LES relaxation reflex, and peristaltic reflexes were noted at time 2 (all, P < 0.05). Graded stimulus-response relationships were evident at time 1 and time 2 during awake and sleep states (P < 0.05). Secondary peristalsis vs. esophago-deglutition response proportions during sleep at time 1 vs. time 2 (P = 0.001) and awake vs. sleep at time 2 (P = 0.02) were distinct. We concluded that sensory-motor effects of esophageal mechanosensitivity, osmosensitivity, and chemosensitivity are advanced in sleep with maturation. Sleep further modulates the frequency recruitment and the type of aerodigestive reflexes.

Pharmacological therapy of gastroesophageal reflux in preterm infants

Although gastroesophageal reflux (GER) is a very common phenomenon among preterm infants, its therapeutic management is still an issue of debate among neonatologists. A step-wise approach should be advisable, firstly promoting nonpharmacological interventions and limiting drugs to selected infants unresponsive to the conservative measures or who are suffering from severe GER with clinical complications. Despite of this, a concerning pharmacological overtreatment has been increasingly reported. Most of the antireflux drugs, however, have not been specifically assessed in preterm infants; moreover, serious adverse effects have been noticed in association to their administration. This review mainly aims to draw the state of the art regarding the pharmacological management of GER in preterm infants, analyzing the best piecies of evidence currently available on the most prescribed anti-reflux drugs. Although further trials are required, sodium alginate-based formulations might be considered promising; however, data regarding their safety are still limited. Few piecies of evidence on the efficacy of histamine-2 receptor blockers and proton pump inhibitors in preterm infants with GER are currently available. Nevertheless, a significantly increased risk of necrotizing enterocolitis and infections has been largely reported in association with their use, thereby leading to an unfavorable risk-benefit ratio. The efficacy of metoclopramide in GER's improvement still needs to be clarified. Other prokinetic agents, such as domperidone and erythromycin, have been reported to be ineffective, whereas cisapride has been withdrawn due to its remarkable cardiac adverse effects.

Esophageal mechanosensitive mechanisms are impaired in neonates with hypoxic-ischemic encephalopathy

OBJECTIVES

To test the hypothesis that esophageal mechanodistention in infants with hypoxic-ischemic encephalopathy (HIE) results in altered upper esophageal sphincter (UES), esophageal body, and lower esophageal sphincter (LES) responses, compared with controls. As a secondary aim, we tested the hypothesis that infants with HIE receiving therapeutic hypothermia had different aerodigestive reflex characteristics than infants with HIE who received traditional neonatal care.

STUDY DESIGN

Provocative esophageal manometry was performed in 34 neonates (27 with HIE and 7 controls). Mechanodistention was performed using graded volumes of air. Peristaltic reflexes, UES contractile reflexes, and LES relaxation reflexes were analyzed for frequency, magnitude, and aberrancies.

RESULTS

Infants with HIE demonstrated more rapid recruitment of responses and greater UES magnitude (P < .05). They had more frequent secondary peristalsis and lower LES nadir pressures with prolonged LES nadir durations (P < .05). Most notable were the prolonged peristaltic response durations and increases in the number of polymorphic waveforms (P < .05). Compared with infants with HIE receiving traditional care, infants with HIE treated with hypothermia had higher UES pressures and shorter peristaltic response duration (P < .05).

CONCLUSIONS

Mechanodistention in infants with HIE results in upregulation of central vagal effects (ie, heightened cholinergic excitatory responses as demonstrated by exaggerated UES contractile reflex activity and heightened inhibitory responses evident by exaggerated LES relaxation reflex activity). Prolonged and poorly coordinated peristaltic responses may underlie dysfunction of aerodigestive regulation. Modulation of sensorimotor aspects of aerodigestive reflexes is altered in infants with HIE, and hypothermia may further modify such effects.