Feed-Thickening Practices in NICUs in the Current Era: Variability in Prescription and Implementation Patterns

BACKGROUND

Feed-thickening for infants in the Neonatal Intensive Care Unit (NICU) is performed due to concerns of dysphagia and gastroesophageal reflux disease (GERD). No standards currently exist regarding feed-thickening prescriptions and practices and this results in variable and potentially unsafe feeding approaches.

METHODS

Electronic surveys were sent to neonatal feeding therapists and providers in order to determine the prescriptions and practices currently being used for feed-thickening in the NICU.

RESULTS

A total of 313 responses were collected. Results revealed the majority of providers use thickened feeds for concerns of dysphagia or GERD with some reporting they thicken expressed breast milk. Variability of thickening prescriptions was noted regarding consistencies, thickening agents, and recipes used. Reported approaches for measuring, mixing, and warming thickened feeds varied.

CONCLUSION

Variability was noted in the feed-thickening prescriptions and practices performed in the NICU. Further research and standardization are required to develop thickening guidelines.

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.

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.

Sildenafil Treatment of Infants With Bronchopulmonary Dysplasia-Associated Pulmonary Hypertension

OBJECTIVE

This study had 2 goals: (1) to identify clinical and demographic characteristics associated with sildenafil exposure for infants with bronchopulmonary dysplasia (BPD)-associated pulmonary hypertension (PH); and (2) to characterize hospital-specific treatment frequency, age at first administration, and length of sildenafil treatment.

METHODS

This retrospective cohort study used data from the Pediatric Health Information System to determine variables associated with sildenafil exposure and between-hospital variations in sildenafil utilization patterns. The study included infants with BPD-PH who were discharged between January 1, 2006, and December 31, 2013.

RESULTS

Within 36 US pediatric hospitals, 3720 infants were diagnosed with BPD, of whom 598 (16%) also had a diagnosis of PH (BPD-PH). Among infants with BPD-PH, 104 infants (17%) received sildenafil. The odds for sildenafil treatment among infants born between 25 and 26 weeks' gestational age (GA) and <24 weeks' GA, respectively, were 2.26 (95% confidence interval [CI]: 1.20-4.24) and 3.21 (95% CI: 1.66-6.21) times those of infants born at 27 to 28 weeks' GA. Severity of BPD correlated with sildenafil exposure, with adjusted odds ratios (ORs) for moderate BPD (OR: 3.03 [95% CI: 1.03-8.93]) and severe BPD (OR: 7.56 [95% CI: 2.50-22.88]), compared with mild BPD. Greater rates of sildenafil exposure were observed among small for GA neonates (OR: 2.32 [95% CI: 1.21-4.46]). The proportion of infants with BPD-PH exposed to sildenafil varied according to hospital (median: 15%; 25th-75th percentile: 0%-25%), as did the median duration of therapy (52 days; 25th-75th percentile: 28-109 days).

CONCLUSIONS

The odds of sildenafil treatment were greatest among the most premature infants with severe forms of BPD. The frequency and duration of sildenafil exposure varied markedly according to institution. Patient-centered trials for infants with BPD-PH are needed to develop evidence-based practices.

Inhaled bronchodilator use for infants with bronchopulmonary dysplasia

OBJECTIVE

To identify factors associated with bronchodilator administration to infants with bronchopulmonary dysplasia (BPD) and evaluate inter-institutional prescribing patterns.

STUDY DESIGN

A retrospective cohort study of <29-week-gestation infants with evolving BPD defined at age 28 days within the Pediatric Health Information System database. Controlling for observed confounding with random-effects logistic regression, we determined demographic and clinical variables associated with bronchodilator use and evaluated between-hospital variation.

RESULT

During the study period, 33% (N=469) of 1429 infants with BPD received bronchodilators. Lengthening mechanical ventilation duration increased the odds of receiving a bronchodilator (odds ratio 19.6 (11 to 34.8) at ⩾ 54 days). There was profound between-hospital variation in use, ranging from 0 to 81%.C ONCLUSION: Bronchodilators are frequently administered to infants with BPD at US children's hospitals with increasing use during the first hospital month. Increasing positive pressure exposure best predicts bronchodilator use. Frequency and treatment duration vary markedly by institution even after adjustment for confounding variables.

Safety and Efficacy of Oral Feeding in Infants with BPD on Nasal CPAP

Safety and efficacy of oral feeding was examined in infants with bronchopulmonary dysplasia (BPD) on nasal continuous positive airway pressure (NCPAP). We hypothesized that repetitive oral feeding enhances aero-digestive outcomes and reduces resource utilization. Data from infants with BPD (37-42 weeks post menstrual age) that were orally fed while on NCPAP (n = 26) were compared with those that were exclusively gavage fed on NCPAP (n = 27). Subject assignment was random and physician practice based. Specifically, we compared the differences in aero-digestive milestones, resource utilization, and safety metrics. Demographic characteristics such as gender distribution, gestational age, and birth weight, clinical characteristics such as frequency of intraventricular hemorrhage and patent ductus arteriosus needing surgical ligation were similar in both groups (p > 0.05). Characteristics of respiratory support and airway milestones were similar in both groups (p > 0.05). However, infants in NCPAP-oral fed group had earlier acquisition of full oral feeding milestone by 17 days (median) versus infants who were not orally fed during NCPAP (p < 0.05). Discharge weights and the frequency of gastrostomy tube placement were also similar in both groups (p > 0.05). There were no tracheostomies in either group. There was no incidence of clinically significant aspiration pneumonia in infants during the period of the oral feeding while on NCPAP. Controlled introduction of oral feedings in infants with BPD during NCPAP is safe and may accelerate the acquisition of oral feeding milestones.

Utilization of inhaled corticosteroids for infants with bronchopulmonary dysplasia

OBJECTIVE

To determine demographic and clinical variables associated with inhaled corticosteroid administration and to evaluate between-hospital variation in inhaled steroid use for infants with bronchopulmonary dysplasia (BPD).

DESIGN

Retrospective Cohort Study.

SETTING

Neonatal units of 35 US children's hospitals; as recorded in the Pediatric Health Information System (PHIS) database.

PATIENTS

1429 infants with evolving BPD at 28 days who were born at <29 weeks gestation with birth weight <1500 grams, admitted within the first 7 postnatal days, and discharged between January 2007-June 2011.

RESULTS

Inhaled steroids were prescribed to 25% (n = 352) of the cohort with use steadily increasing during the first two months of hospitalization. The most frequently prescribed steroid was beclomethasone (n = 194, 14%), followed by budesonide (n = 125, 9%), and then fluticasone (n = 90, 6%). Birth gestation <24 weeks, birth weight 500-999 grams, and prolonged ventilation all increased the adjusted odds of ever receiving inhaled corticosteroids (p<0.05). Wide variations between hospitals in the frequency of infants ever receiving inhaled steroids (range: 0-60%) and the specific drug prescribed were noted. This variation persisted, even after controlling for observed confounders.

CONCLUSIONS

Inhaled corticosteroid administration to infants with BPD is common in neonatal units within U.S. Children's hospitals. However, its utilization varies markedly between centers from no treatment at some institutions to the majority of infants with BPD being treated at others. This supports the need for further research to identify the benefits and potential risks of inhaled steroid usage in infants with BPD.

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.

Practice Variance, Prevalence, and Economic Burden of Premature Infants Diagnosed With GERD

OBJECTIVE

To determine the practice variance, prevalence, and economic burden of clinically diagnosed gastroesophageal reflux disease (GERD) in preterm infants.

METHODS

Applying a retrospective cohort study design, we analyzed data from 18 567 preterm infants of 22 to 36 weeks' gestation and >400 g birth weight from the NICUs of 33 freestanding children's hospitals in the United States. GERD prevalence, comorbidities, and demographic factors were examined for their association with average length of stay (LOS) and hospitalization cost.

RESULTS

Overall, 10.3% of infants received a diagnosis of GERD (95% confidence interval [CI]: 9.8-10.7). There was a 13-fold variation in GERD rates across hospitals (P < .001). GERD diagnosis was significantly (P < .05) associated with bronchopulmonary dysplasia and necrotizing enterocolitis, as well as congenital anomalies and decreased birth weight. GERD diagnosis was associated with $70 489 (95% CI: 62 184-78 794) additional costs per discharge and 29.9 additional days in LOS (95% CI: 27.3-32.5).

CONCLUSIONS

One in 10 of these premature NICU infants were diagnosed with GERD, which is associated with substantially increased LOS and elevated costs. Better diagnostic and management strategies are needed to evaluate reflux-type symptoms in this vulnerable NICU population.

Physiology of esophageal sensorimotor malfunctions in neonatal neurological illness

We aimed to define the sensorimotor characteristics of aero-digestive reflexes evoked upon midesophageal provocations in neuropathology infants. Provocative esophageal motility testing was performed in 20 neuropathology infants and 10 controls at 42.3 ± 0.6 and 38.9 ± 0.9 wk postmenstrual age. Data from 1,073 infusions were examined for the sensory thresholds, response frequencies, response magnitude of upper esophageal sphincter (UES) contractile reflexes, lower esophageal sphincter (LES) relaxation reflexes, and peristaltic reflexes using mixed statistical models. Threshold volumes for air and liquid in neuropathology and control infants were similar for all reflexes. Graded air- and liquid volume-dependent UES contractile reflex, LES relaxation reflex, and peristaltic reflex frequency recruitment were present in neuropathology and control subjects for the media (P < 0.0001) and the reflexes (P < 0.0001). In neuropathology infants (vs. controls), UES contractile magnitude is higher (P < 0.0001); LES relaxation reflex occurred earlier (P = 0.008); LES nadir duration lasted longer (P = 0.006); secondary peristalsis is the chief method of esophageal clearance (P < 0.0001); pharyngeal swallows and deglutition apneas are less frequent (P = 0.001); proximal, midesophageal waveform magnitudes and duration are exaggerated (P < 0.008). UES contractile reflex was longer with liquid than air in both groups (P = 0.03). We concluded that 1) perception to midesophageal provocation remains preserved in neuropathology neonates; 2) sustained and exaggerated myogenic response from afferent activation is evident by increased excitatory efferent outputs to the UES and esophageal body and increased inhibitory efferent outputs to the LES; 3) dysfunctional regulation of pharyngeal swallowing and infrequent deglutition responses indicate the possibility of impaired descending modulation and central malfunctions of brainstem and vagal nuclei.

Pathophysiology of aerodigestive pulmonary disorders in the neonate

No test can provide a definitive diagnosis of aerodigestive disease. When interpreting tests, one should weigh the benefits and weaknesses of different technologies and methods, scientific appropriateness of the testing conditions, clinicopathologic correlation, and pharmacologic approaches. Gastroesophageal reflux disease (GERD) symptoms and airway symptoms can coexist, and they cannot be distinguished without specific testing and direct observations. Important aerodigestive disorders include dysphagia, GERD, and aggravation of airway injury due to malfunctions of swallowing or airway protection mechanisms. Objective evaluation of aerodigestive reflexes and symptom correlation may provide support for evidence-based personalized management of feeding and airway protection strategies.

Clinical Perspectives on Esophageal Disorders in Infants

Esophageal pathologies are complex and lend themselves to multivariable analysis before a definitive diagnosis can be considered. It is imperative that the clinician establish a methodology for selecting the appropriate technological assessment within scientific testing parameters to establish optimal clinicopathological presentation and determine best practice for patient care.

Esophageal sensation in premature human neonates: temporal relationships and implications of aerodigestive reflexes and electrocortical arousals

Electrocortical arousal (ECA) as an effect of visceral provocation or of its temporal relationships with aerodigestive reflexes in premature neonates is not known. We tested the hypothesis that esophageal provocation results in both esophageal reflex responses and ECAs during sleep and that ECAs are dependent on the frequency characteristics of esophageal neuromotor responses. We defined the spatiotemporal relationship of ECAs in relation to 1) spontaneous pharyngoesophageal swallow sequences and gastroesophageal reflux (GER) events and 2) sensory-motor characteristics of esophageal reflexes. Sixteen healthy premature neonates born at 27.9 ± 3.4 wk were tested at 36.8 ± 1.9 wk postmenstrual age. Ninety-five midesophageal and 31 sham stimuli were given in sleep during concurrent manometry and videopolysomnography. With stimulus onset as reference point, we scored the response latency, frequency occurrence and duration of arousals, peristaltic reflex, and upper esophageal sphincter contractile reflex (UESCR). Changes in polysomnography-respiratory patterns and esophageal sensory-motor parameters were scored by blinded observers. Significantly (for each characteristic listed, P < 0.05), swallow sequences were associated with arousals and sleep state changes, and arousals were associated with incomplete peristalsis, response delays to lower esophageal sphincter relaxation, and prolonged esophageal clearance. GER events (73.5%) provoked arousals, and arousals were associated with response delays to peristaltic reflexes or clearance, sleep state modification, and prolonged respiratory arousal. Midesophageal stimuli (54%) provoked arousals and were associated with increased frequency, prolonged latency, prolonged response duration of peristaltic reflexes and UESCR, and increased frequency of sleep state changes and respiratory arousals. In human neonates, ECAs are provoked upon esophageal stimulation; the sensory-motor characteristics of esophageal reflexes are distinct when accompanied by arousals. Aerodigestive homeostasis is defended by multiple tiers of aerodigestive safety mechanisms, and when esophageal reflexes are delayed, cortical hypervigilance (ECAs) occurs.

Impact of feeding strategies on the frequency and clearance of acid and nonacid gastroesophageal reflux events in dysphagic neonates

BACKGROUND

Feeding difficulties and gastroesophageal reflux (GER) are common problems in neonates. The authors hypothesize that GER could be influenced by feeding mechanics by evaluating the effects of feeding volumes, feeding durations, feeding flow rates, and caloric density on the chemical composition and clearance of GER in dysphagic neonates.

METHODS

Symptomatic dysphagic neonates (n = 35) underwent evaluation for suspected GER using pH-impedance methods.

RESULTS

The proportions of acid and nonacid GER were different during the first, second, and third postprandial hours (P < .0001). Prolonged feeding duration was significantly associated with decreased total, nonacid GER and BCT (P < .03). Significant positive correlations (P < .05) were detected between feeding flow rate vs frequency of total, nonacid GER and BCT. Significant positive correlation (P = .002) was noted between feeding volume and BCT. BCT decreased with each hourly interval (analysis of variance [ANOVA] P < .05); however, ACT increased with each hourly interval (ANOVA P = .05). Comparison between BCT and ACT at each postprandial hour is remarkable for longer ACT during the second and third hours after the initiation of feed (P ≤ .001). No significant correlation was noted between the milk types (breast milk or formula) or caloric density with regard to the GER characteristics. Oral-fed infants had more GER events than gavage-fed infants.

CONCLUSIONS

Prolonged feeding durations and slower flow rates are associated with decreased frequency of GER. Modification of feeding duration and flow rate can be a useful adjunct to ameliorate GER in dysphagic neonates.

Esophageal disease in pediatrics

The following on esophageal disease in pediatrics contains commentaries on acquisition of neuromuscular maturation; physiology of esophageal peristaltic and sphincteric reflexes; implications for clinical practice; and conditions that predispose to severe gastroesophageal reflux disease (GERD) in children with potential risk for esophageal cancer.

Significance of gastroesophageal refluxate in relation to physical, chemical, and spatiotemporal characteristics in symptomatic intensive care unit neonates

Gastroesophageal reflux disease (GERD) is a frequent consideration in intensive care unit neonates. We tested the hypothesis that symptoms in GERD are dependent on the spatiotemporal and physicochemical characteristics of reflux events by evaluating the symptom sensitivity index (SSI) and symptom index (SI) in relation to the refluxate characteristics. Thirty symptomatic neonates (30.7 ± 0.8 wk gestation) were evaluated using manometry and pH-impedance methods. During 704.3 h of recordings, 2063 gastroesophageal reflux (GER) were observed; 54% of the GER were associated with symptoms. Defined by physical characteristics, there were 51.3% liquid, 29.1% gas, and 19.6% mixed GER. Defined by chemical characteristics, there were 48.5% acid and 51.5% nonacid GER. Defined by most proximal extent, 79.2% were supra-UES (upper esophageal sphincter) and 20.8% were infra-UES. Higher SSI was noted with pH-only events (p < 0.0001 versus pH-impedance events). Higher SI was noted with movement symptoms (versus sensory, p = 0.04). In a subset analysis, the frequencies of GER events, acid clearance time, and SSI were all greater in chronic lung disease versus none (p < 0.001). In conclusion, clinical significance of symptoms as measured by SSI and SI and characterization of spatial-temporal-physical-chemical nature of GER events as defined by pH-impedance methods clarifies the definition of GERD.

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

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

Physiology and pathophysiology of glottic reflexes and pulmonary aspiration: from neonates to adults

Pulmonary aspiration is the consequence of abnormal entry of fluid, particulate material, or endogenous secretions into the airway. The two main types of aspiration scenarios include anterograde aspiration, which occurs during swallowing, and retrograde aspiration, which can occur during gastroesophageal reflux (GER) events. The important structures that protect against aspiration include the aerodigestive apparatus: pharynx, upper esophageal sphincter, esophageal body, glottis and vocal cords, and airway. In this article we review the neuroanatomy, physiology, and pathophysiology pertinent to glottic reflexes and airway aspiration across the age spectrum from neonates to adults. We also discuss recent advances in our understanding of glottal reflexes and the relationship of these reflexes to developmental anatomy and physiology, the pathophysiology of aspiration, and aerodigestive interactions.

Impact of prematurity and co-morbidities on feeding milestones in neonates: a retrospective study

OBJECTIVE

Feeding problems are an important area of neonatal morbidity that requires attention. We defined the feeding milestones related to transition to per oral feeding among premature infants based on gestational (GA) and postmenstrual ages (PMA), and elucidated the co-morbidity variables affecting with these skills.

STUDY DESIGN

Feeding progress was tracked during the first hospitalization in a retrospective study involving 186 infants. We measured the age at acquisition of first feedings, maximum gavage feedings and maximum oral feedings. Resource usage measures included the total length of hospital stay (LOS), duration of gavage tube and duration of respiratory support. Effects of perinatal and co-morbidity factors on the acquisition of feeding milestones were evaluated. ANOVA, t-test, Wilcoxon rank sum test, chi(2) test, univariate and multivariate analysis, stepwise linear regression analysis and logistic regression analysis were applied as appropriate. Data were presented as mean+/-s.d., or as stated. P<0.05 was considered significant.

RESULT

We stratified the data into three groups based on GA at birth: <28.0 weeks (group-1), 28.0 to 32.0 weeks (group-2) and 32.0 to 35.0 weeks (group-3). Compared with group-3, group-1 needed four-fold more ventilation and five-fold more continuous positive airway pressure (CPAP) duration (all P<0.001); whereas group-2 needed two-fold more CPAP duration. Age at first feed correlated with age at full gavage feedings and age at full oral feedings (r=0.53 and r=0.71, both P<0.0001). Age at full gavage feedings correlated with age at full oral feedings (r=0.81, P<0.0001). Univariate analysis was significant for GA age, hypotension, the effects of gastroesophageal reflux, and duration of ventilation and CPAP on the PMA at maximal oral feedings (all P<0.05); multivariate analysis for these variables was also significant (R (2)=0.58, P<0.0001). The success rate for oral feedings at discharge accelerated with GA maturation and caffeine use; on the other hand, the need for respiratory support and management of positive blood culture were associated with failure rates (P<0.05).

CONCLUSION

Infants < 28 weeks GA have significant feeding delays with respect to initiation and progression to maximal gavage and oral feedings, as well as prolonged LOS. Infants >28 weeks GA attained successful feeding milestones by similar PMA. Specific aero-digestive co-morbidities significantly affected maximal oral feeding milestone. Delays in achieving maximum gavage and maximum oral feeding milestones suggest delays with the development of control and regulation of foregut motility.

Definition and implications of novel pharyngo-glottal reflex in human infants using concurrent manometry ultrasonography

OBJECTIVES

Glottal relationships during swallowing dominate the etiology of dysphagia. We investigated the pharyngo-glottal relationships during basal and adaptive swallowing.

METHODS

Temporal changes in glottal closure kinetics (frequency, response latency, and duration) with spontaneous and adaptive pharyngeal swallows were defined in 12 infants using concurrent pharyngoesophageal manometry and ultrasonography of the glottis.

RESULTS

Frequency, response latency, and duration of glottal closure with spontaneous swallows (n=53) were 100%, 0.27+/-0.1 s, and 1+/-0.22 s, respectively. The glottis adducted earlier (P<0.0001 vs. upper esophageal sphincter relaxation) within the same respiratory phase as swallow (P=0.03). With pharyngeal provocations (n=41), glottal adduction (pharyngo-glottal closure reflex (PGCR)) was noted first and then again with pharyngeal reflexive swallow (PRS). The frequency, response latency, and duration of glottal closure with PGCR were 100%, 0.56+/-0.13 s, and 0.52+/-0.1 s, respectively. Response latency to PRS was 3.24+/-0.33 s; the glottis adducted 97% within 0.36+/-0.08 s in the same respiratory phase (P=0.03), and remained adducted for 3.08+/-0.71 s. Glottal adduction was the quickest with spontaneous swallow (P=0.04 vs. PGCR), and the duration was the longest during PRS (P<0.005 vs. PGCR or spontaneous swallow).

CONCLUSIONS

Glottal adduction during basal or adaptive swallowing reflexes occurs in either respiratory phase, thus ensuring airway protection against pre-deglutitive or deglutitive aspiration. The independent existence and magnitude (duration of adduction) of PGCR suggests a hypervigilant state of the glottis in preventing aspiration during swallowing or during high gastroesophageal reflux events. Investigation of pharyngeal-glottal relationships with the use of noninvasive methods may be more acceptable across the age spectrum.

Feeding abilities in neonates with congenital heart disease: a retrospective study

OBJECTIVE

An important area concerning morbidity among infants with congenital heart defects (CHD) is related to feeding problems. Our objectives were to characterize the evolution of feeding milestones related to transition to per oral feeding among infants with CHD, and to identify associated variables impacting the feeding abilities. Specifically, we differentiated the feeding characteristics in neonates with acyanotic vs cyanotic CHD.

STUDY DESIGN

Feeding progress was tracked during the first hospitalization in a retrospective chart review study involving 76 infants (29 acyanotic, 47 cyanotic CHD). The ages at which the following milestones attained were recorded: first feeds, maximum gavage feeds, first nipple feeds and maximum nipple feeds, in addition to the length of hospital stay. Effects of perinatal factors, duration of respiratory support, vasopressor and narcotic use and use of cardiopulmonary bypass on the feeding milestones were also evaluated. ANOVA, t-test, and stepwise linear regression analysis were applied as appropriate. Data stated as mean+/-s.e.m., or %; P<0.05 was considered significant.

RESULT

Prenatal and birth characteristics were similar (P=NS) between the neonates with acyanotic and cyanotic CHD. Cyanotic CHD required three times prolonged use of ventilation, narcotics and vasopressor use (all P<0.05, compared to the acyanotic group). In the acyanotic group, prolonged respiratory support correlated linearly with time to attain maximal gavage feeds and nippling (both, R2=0.8). In the cyanotic group, delayed initiation of gavage feeds and prolonged respiratory support both correlated linearly with time to attain maximal gavage feeds and nippling (both, R2=0.8). Age at first gavage feed correlated with maximum gavage feeds among neonates with cyanotic CHD, and first nipple feed correlated with maximum nipple feeds among all groups (P<0.01). Use of cardiopulmonary bypass in cyanotic CHD delayed the feeding milestones and prolonged the length of stay (both, P<0.05 vs non-bypass group); similar findings were not seen in the acyanotic group.

CONCLUSION

In contrast to neonates with acyanotic CHD, cyanotic CHD group had significant delays with (a) feeding readiness, (b) successful gastric feeding, (c) oromotor readiness and (d) successful oromotor skills. Co-morbid factors that may directly influence the delay in feeding milestones include the (a) duration of respiratory support and (b) use of cardiopulmonary bypass. Delays in achieving maximum gavage and maximum nippling may suggest foregut dysmotility and oropharyngeal dysphagia.

Effect of postnatal maturation on the mechanisms of esophageal propulsion in preterm human neonates: primary and secondary peristalsis

OBJECTIVES

The changes in esophageal propulsive characteristics during maturation are not known. Our aim was to define the effects of postnatal maturation on esophageal peristaltic characteristics in preterm human neonates. We tested the hypotheses that: (i) maturation modifies esophageal bolus propulsion characteristics, and (ii) the mechanistic characteristics differ between primary and secondary peristalsis.

METHODS

Esophageal motility in 10 premature neonates (mean 27.5 weeks gestational age) was evaluated twice at 33.8 weeks (time 1, earlier study) and 39.2 weeks (time 2, later study) mean postmenstrual age. Esophageal manometry waveform characteristics (amplitude and duration, peristaltic velocity, and intrabolus pressure domains) were analyzed during spontaneous primary peristalsis and infusion-induced secondary peristalsis. Repeated-measures and unstructured variance-covariance or compound symmetry matrixes were used for statistical comparison. Values stated as least squares means+/-s.e.m. or percent.

RESULTS

A total of 200 primary peristalsis and 227 secondary peristalsis events were evaluated. Between time 1 and time 2: (i) proximal esophageal waveform amplitude increased (P<0.02), with primary peristalsis (38+/-6 vs. 48+/-7 mm Hg) and with secondary peristalsis (34+/-6 vs. 46+/-5 mm Hg); (ii) distal esophageal waveform amplitude was similar (P=NS), with primary peristalsis (42+/-4 vs. 43+/-4 mm Hg) and secondary peristalsis (29+/-3 vs. 32+/-4 mm Hg); (iii) proximal esophageal waveform onset to peak duration decreased (P=0.02) with primary (2.6+/-0.3 vs. 1.9+/-0.1 s, P<0.003) and with secondary peristalsis (2.2+/-0.2 vs. 1.8+/-0.1 s); (iv) distal esophageal waveform onset to peak duration decreased (P=0.01) with primary (2.4+/-0.3 vs. 1.8+/-0.1 s) and with secondary peristalsis (1.9+/-0.2 vs. 1.5+/-0.1 s); (v) effects of identical stimulus volume on intrabolus pressure were similar (P=NS); however, greater infusion volumes (2 vs. 1 ml) generated higher intrabolus pressure at both time 1 and time 2 (both Ps<0.05). Between primary and secondary peristalsis (mechanistic variable): (i) no differences were noted at either period, with proximal esophageal waveform amplitudes (P=NS); (ii) differences were noted with distal esophageal waveform amplitudes at each time period (P=0.0002); (iii) no differences were noted with both esophageal waveforms duration at either period (P=NS); (iv) peristaltic velocity was faster with secondary peristalsis than with primary peristalsis at either period (at earlier study, 7.9+/-1.4 vs. 2.5+/-1.4 cm/s and at later study 6.2+/-1.6 vs. 1.2+/-1.5 cm/s, both Ps<0.01).

CONCLUSIONS

In preterm neonates, longitudinal maturation modulates the characteristics of primary and secondary peristalsis. Differences in proximal striated muscle and distal smooth muscle activity during peristalsis are evident. Peristaltic velocity is faster with secondary peristalsis. These findings may represent maturation of central and peripheral neuromotor properties of esophageal bolus propulsion in healthy preterm human neonates.

Spatiotemporal characteristics of acid refluxate and relationship to symptoms in premature and term infants with chronic lung disease

BACKGROUND AND OBJECTIVES

The prevalence of gastroesophageal reflux (GER) is high among infants with chronic lung disease (CLD), and the associated pathogenic mechanisms are not clear. The relationship of symptoms to the extent or duration of acid reflux events (AREs) is not well known in preterm or term infants. Our aim was to evaluate the relationship between spatial (height) and temporal (duration) characteristics of AREs (pH <4.0) with symptoms in CLD. We tested the hypothesis that in infants with CLD, AREs into the pharynx are associated with increased symptom occurrence and delayed clearance.

METHODS

Nine infants born at 29.8 +/- 5.5 wk gestation (mean +/- SD, range 24.7-39.0 wk) with CLD were evaluated for GER at 49.7 +/- 8.0 wk postmenstrual age (mean +/- SD, range 39.9-67.4 wk). Esophageal manometry was first performed to determine the nares-lower esophageal sphincter (LES) distance. A pH-impedance probe was placed at 87% of the nares-LES distance, and a recording was performed for about 24 h at cribside. Symptoms (respiratory, sensory, and movement) were documented by nurses that were blinded to the pH-impedance recordings. A symptom was considered associated with an ARE if it occurred 2 min before, during, or 2 min after the ARE. The proximal extent and associated clearance mechanisms were correlated with symptom sensitivity index (SSI = number of AREs with symptoms/total AREs *100). Multiple logistic regression methods, analysis of variance (ANOVA) models, and chi(2) tests were performed. Data are described as median, mean +/- SD, or %.

RESULTS

A total of 511 AREs, based on pH-Impedance methods, were analyzed from 203 h of recordings in the nine infants. The distal esophagus was the maximal height reached in 80% of AREs (P < 0.001, compared to other esophageal segments). Overall 33% of the AREs were associated with symptoms, and an SSI of 77% was noted with high AREs into the pharynx. The average acid clearance time was prolonged with symptomatic AREs versus nonsymptomatic AREs by 3.5-fold (P < 0.001).

CONCLUSIONS

The occurrence and frequency of symptoms with AREs depend on the most proximal extent of the ARE and the acid clearance time.

Correlation of glottal closure using concurrent ultrasonography and nasolaryngoscopy in children: a novel approach to evaluate glottal status

OBJECTIVES

Endoscopic procedures to assess aerodigestive symptoms by evaluating glottal motion are not practical in neonates because of small nares, respiratory difficulties, or additional stress. Our objective was to determine the temporal correlation between concurrent nasolaryngoscopy (NLS) and ultrasonography (USG) evaluation of glottal motion.

METHODS

Simultaneous USG of the glottis was performed in 10 subjects (5 males, 5 females, age = 4.5 months to 7.1 years) that underwent diagnostic flexible outpatient NLS. The USG transducer was placed on the anterior neck at the level of the vocal cords. The video signals from NLS and USG were integrated and synchronized into real-time cine loops of 1-min duration.

RESULTS

Frame-by-frame evaluation of 10,800 frames identifying glottal opening and closure time was compared between the two modalities by three observers and the timing of glottal closure was marked. Two investigators, blinded to NLS images, identified ultrasonographically determined glottal closure with 99% and 100% accuracy, and the mean probability of missing a closure frame was 0.007 (95% CI = 0.0008-0.024).

CONCLUSIONS

Temporal characteristics of glottal motion can be quantified by USG with perfect reliability and safety. This method can be useful in measuring the presence and the duration of laryngeal adduction.

Esophago-glottal closure reflex in human infants: a novel reflex elicited with concurrent manometry and ultrasonography

BACKGROUND AND AIMS

Our aims were to identify and characterize the glottal response to esophageal mechanostimulation in human infants. We tested the hypotheses that glottal response is related to the type of esophageal peristaltic response, stimulus volume, and respiratory phase.

METHODS

Ten infants (2.8 kg, SD 0.5) were studied at 39.2 wk (SD 2.4). Esophageal manometry concurrent with ultrasonography of the glottis (USG) was performed. The sensory-motor characteristics of mechanostimulation-induced esophago-glottal closure reflex (EGCR, adduction of glottal folds upon esophageal provocation) were identified. Mid-esophageal infusions of air (N = 41) were given and the temporal relationships of glottal response with deglutition, secondary peristalsis (SP), and the respiratory phase were analyzed using multinomial logistic regression models.

RESULTS

The frequency occurrence of EGCR (83%) was compared (P < 0.001) with deglutition (44%), SP (34%), and no esophageal responses (22%). The odds ratios (OR, 95% CI) for the coexistence of EGCR with SP (0.4, 0.06-2.2), deglutition (1.9, 0.1-26), and no response (1.9, 0.4-9.0) were similar. The response time for esophageal reflexes was 3.8 (SD 1.8) s, and for EGCR was 0.4 (SD 0.3) s (P < 0.001). Volume-response relationship was noted (1 mL vs 2 mL, P < 0.05). EGCR was noted in both respiratory phases; however, EGCR response time was faster during expiration (P < 0.05).

CONCLUSION

The occurrence of EGCR is independent of the peristaltic reflexes or the respiratory phase of infusion. The independent existence of EGCR suggests a hypervigilant state of the glottis to prevent retrograde aspiration during GER events.

Upstream effect of esophageal distention: effect on airway

The pharyngoesophageal segment of the foregut has an important function in steering clear of luminal contents from the airway, across the age spectrum from a premature neonate to an aging adult. This complex neuromuscular interaction between the esophagus and the airway is maintained by a variety of mechanisms mediated by the parasympathetic and sympathetic afferent and efferent outflows involving the myenteric plexus, glossopharyngeal and vagus cranial nerves, phrenic nerve, and brainstem nuclei. The esophageal provocation during gastroesophageal reflux events results in esophageal distention, followed by responses in the esophagus, the airway, or both. Studies involving esophageal provocation in human adults and animal models are beginning to illuminate the pathogenetic mechanisms associated with aerodigestive tract disease. However, studies pertinent to this topic in infants or children have been lacking. In this paper, we review recent advances concerning the motor responses of the esophagus and the airway ensuing upon esophageal distention. Recent advances in methods to evaluate aerodigestive responses in infants that have been validated are discussed.

Characteristics of upper oesophageal sphincter and oesophageal body during maturation in healthy human neonates compared with adults

We evaluated the upper oesophageal sphincter (UOS) relationship with oesophageal body during primary peristalsis (PP) sequences in healthy human neonates during maturation and compared with that of healthy adult volunteers. Forty-nine studies were performed using a water perfusion manometry system and a specially designed oesophageal catheter with a UOS sleeve concurrent with submental electromyogram in 31 subjects in supine position (18 preterm neonates, 29.9 +/- 2.5 weeks gestation; four full-term neonates, 39.3 +/- 1.0 weeks gestation; and nine adults, 18-65 years). The preterm neonates were studied longitudinally at 33 and 36 weeks postmenstrual age (PMA) and full-term born at 40 weeks PMA. Data were compared between the groups to recognize the effects of gestation, postnatal age and ageing. We evaluated 403 consecutive spontaneous solitary swallows during maturation (preterm at time-1 vs time-2) and growth (preterm and full-term vs adults) and observed significant (P < 0.05) differences in the basal UOS resting pressure, UOS relaxation characteristics, proximal and distal oesophageal body amplitude, duration, propagation and peristaltic velocity. Characteristics of UOS and PP are well-developed by 33 weeks PMA and undergo further maturation during the postnatal period, and are significantly different from that of adult.

Antroduodenal motility and feeding outcome among neonatal extracorporeal membrane oxygenation survivors

OBJECTIVES

Feeding difficulties are common among survivors of extracorporeal membrane oxygenation (ECMO). In this study, we characterized antroduodenal motor patterns and feeding outcomes among 10 ECMO survivors.

METHODS

Intestinal motor patterns were recorded in 10 ECMO survivors within 48 hours of the initiation of enteral feeding. Subsequent feeding outcomes were tracked until discharge. We compared the motor patterns of infants achieving full oral feedings by 1 month postnatal age with those who did not achieve full oral feedings by 1 month postnatal age.

RESULTS

In infants failing to achieve full oral feedings, duodenal clusters occupied less of the total record (P < 0.05), and clusters had significantly lower amplitude (P < 0.05) than were seen in successful infants. Infants failing to achieve full oral feedings had greater time spent in motor quiescence (P < 0.05) than successful infants. Neither group had migrating motor complexes during fasting or mature duodenal motor responses to feeding. At discharge, six infants with feeding failure were more likely to require tube feeding, and the hospital stay was 3.6 times longer. Intracranial abnormalities were detected by computed tomography scan in five of six infants with feeding failure.

CONCLUSIONS

Early intestinal dysmotility in infants surviving ECMO is associated with later feeding difficulties and prolonged hospitalization.

Manometric evaluation of esophageal-protective reflexes in infants and children

In adults, esophageal motor responses facilitate forward, or aboral, transit during swallowing, and protect the aerodigestive tract during retrograde movement of the bolus, which may occur with gastroesophageal reflux. It is unclear in the pediatric literature whether the activation of appropriate esophageal motor defense responses occurs during these events in infants. This investigation therefore studied the esophageal motor responses during the basal state and upon esophageal stimulation in infants. Using the water-perfusion manometry technique and a specially designed manometric catheter, 3 likely mechanisms that may protect the aerodigestive tract were recognized: secondary peristalsis, esophago-upper esophageal sphincter contractile reflex, and esophagodeglutition response.

Parotid swelling in a premature neonate

Suppurative parotitis in neonates is very rare. We report a case of unilateral suppurative parotitis in a 29-week gestation age infant, who recovered completely following medical treatment. Diagnosis was by clinical examination and microbiology, and parotid involvement confirmed by computed tomographic (CT) scan. The causative organism was coagulase negative Staphylococcus epidermidis.

Esophageal and upper esophageal sphincter motor function in babies

The incidence of concomitant feeding and airway-related disorders is high among premature infants and babies with congenital anomalies. The cause of these disorders is commonly attributed to foregut dysfunction, and the approach to diagnosis and management is largely empiric. Management strategies usually are based on the failure to improve feeding tolerance with advancing maturation and the presence of supraesophageal complications of reflux disease. Very little information exists about the functional development of deglutitive and airway-protective mechanisms in neonates. The purpose of this article is to review the available information on esophageal and upper esophageal sphincter (UES) motor function in human infants. Understanding the maturation of the motor functions of the pharynx-UES and esophagus and related airway-protection responses is essential for determining the pathophysiologic basis of feeding-related airway disorders.

Regulation of migrating motor complexes by motilin and pancreatic polypeptide in human infants

In adults, migrating motor complexes (MMCs) appear to be partially under hormonal modulation by motilin and pancreatic polypeptide. Preterm infants do not exhibit MMCs until 32 wk of gestation. Although plasma concentrations of motilin are similar in infants and adults, it is not known if actual hormonal modulation of MMCs is present in infants. In the first study we assessed whether plasma concentrations of motilin and pancreatic polypeptide surge with the occurrence of MMCs in term infants. In the second study we assessed whether erythromycin, a motilin receptor agonist, could induce migrating motor activity in preterm and term infants. In the first study we recorded motor activity in nine term infants who had never been fed. We determined plasma concentrations of motilin and pancreatic polypeptide in the presence and absence of MMCs. In the second study we gave the motilin agonist erythromycin intragastrically to 21 infants at a range of 24-42 wk of gestation to assess whether migrating activity could be induced via the motilin receptor. In the first study, plasma concentrations of motilin were similar during the presence and absence of MMCs, as were plasma concentrations of pancreatic polypeptide. In the second study, the administration of erythromycin induced the appearance of migrating activity in 7 of 14 infants who were older than 32 wk but in none of the infants who was younger than 32 wk. Although the motilin receptor appears to be functionally present beyond 32 wk of gestation, as assessed by in indirect pharmacologic challenge, hormonal modulation of migrating activity in the neonate by plasma motilin and pancreatic polypeptide is absent.

Acute and chronic intestinal motor activity responses to two infant formulas

OBJECTIVE

Preterm formulas are nutritionally better for preterm infants; however, it has been observed that these formulas cause more feeding intolerance than do regular formulas. Because intestinal motor activity is responsible for the aboral movement of intraluminal nutrients, the purpose of this study was to evaluate intestinal motor activity responses to two infant formulas: 84 and 100.8 J/oz.

STUDY DESIGN AND RESULTS

Intestinal motor activity was recorded in 52 preterm infants who had never been fed and who were randomly assigned to receive small enteral feedings (24 mL/kg per day) for 10 days with one of two commonly used infant formulas. In a subset of 26 of these infants, acute motor responses to both formulas were also evaluated. At the end of the study period, motor activity during fasting did not differ between the two groups of infants. However, motor responses during feeding to the two formulas differed significantly. When infants were fed for the first time, their motor activity increased compared with fasting when they were fed the 84-J/oz formula but decreased when they were fed the 100.8-J/oz formula. These differences in motor responses to the two formulas were not present 10 days later. These differences in motor responses to the 100.8- and 84-J/oz formulas were even more pronounced among the 7 infants who subsequently developed feeding intolerance to the 100.8-J/oz formula during the 10-day study period.

CONCLUSION

Inhibition of motor responses to calorically denser formulas during active feeding in a subset of preterm infants may underlie the feeding intolerance they experience when they are fed these formulas. However, this inhibitory response diminishes with age, suggesting that denser formulas can be reintroduced later in life to these infants.