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 (SAcid), bolus (SBolus), acid and bolus (SAcid+Bolus), and none (SNone) 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) SAcid as SAP ≥ 95% for acid (pH < 4), (2) SBolus as SAP ≥ 95% for bolus, (3) SAcid+Bolus as SAP ≥ 95% for acid and bolus, or (4) SNone as SAP < 95% for acid and bolus. RESULTS: Esophageal sensitivity prevalence (SAcid, SBolus, SAcid+Bolus, SNone) was 28 (10%), 94 (34%), 65 (23%), and 92 (33%), respectively. Emesis occurred more in SBolus and SAcid+Bolus vs SNone (p < 0.05). Magnitude (#/day) of cough and emesis events increased with SBolus and SAcid+Bolus vs SNone (p < 0.05). SAcid+Bolus had increased acid exposure vs SNone (p < 0.05). Distributions of feeding and breathing methods were distinct in infants with SBolus vs SNone (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 SBolus and SAcid+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 SBolus and SAcid+Bolus (p < 0.05) but lesser with Trach (p < 0.001). Number of emesis events/day were greater with SBolus and SAcid+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.

Mechanisms of bradycardia in premature infants: Aerodigestive-cardiac regulatory-rhythm interactions.

OBJECTIVE: Eating difficulties coupled with cardiorespiratory spells delay acquisition of feeding milestones in convalescing neonates, and the mechanisms are unclear. Aims were to examine and compare the pharyngoesophageal-cardiorespiratory (PECR) response characteristics: (a) in control neonates and those with recurrent bradycardia spells; and (b) during pharyngeal stimulation when bradycardia occurs versus when no bradycardia occurs. METHODS: Preterm infants (N = 40, 27 ± 3 weeks gestation), underwent concurrent pharyngoesophageal manometry, electrocardiography, respiratory inductance plethysmography, and nasal airflow thermistor to evaluate pharyngoesophageal motility, heart rate (HR), and respiration during graded abrupt pharyngeal sterile water stimuli. Infants with recurrent bradycardia (N = 28) and controls (N = 12) were evaluated at 38 (38-40) and 39 (38-40) weeks postmenstrual age, respectively. Comparisons were performed (a) between study and control groups; and (b) among HR responses of <80 BPM, 80-100 BPM, and >100 BPM. RESULTS: Overall, characteristics of PECR responses in infants with a history of recurrent bradycardia (vs. controls) did not differ (p > .05). However, when pharyngeal stimulus induced severe bradycardia (<80 BPM): prolonged respiratory rhythm change, increased pharyngeal activity, increased esophageal dysmotility (as evidenced by prolonged esophageal inhibition and motor activity), and prolonged lower esophageal sphincter relaxation were noted (all p < .05). CONCLUSIONS: In control infants and those with recurrent bradycardia, pharyngeal stimulation results in similar PECR response characteristics. However, when severe bradycardia occurs, PECR response characteristics are distinct. The mechanisms of severe bradycardia spells are related to abnormal prolongation of vagal inhibitory effects on cardiorespiratory rhythms in conjunction with prolonged esophageal inhibition and delays with terminal swallow.