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

Abstract

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.

Effect of nasal noninvasive respiratory support methods on pharyngeal provocation-induced aerodigestive reflexes in infants

“…If LES relaxation occurred then the magnitude of relaxation was measured, i.e., nadir relaxation pressure (mmHg) and duration of relaxation (s) (17,26).…”

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

“…These characteristics are analyzed as defined before (15,16,18,29), and described briefly as follows: 1) Resting UES pressure was measured as an average of five UES pressure measurements at end expiration observed prior to stimulus or spontaneous swallow. 2) Response onset to UESCR is defined as the time taken from the onset of stimulus for an increase in UES pressure of at least 4 mmHg above baseline.…”

Efficacy of aminophylline vs. caffeine for preventing apnea of prematurity

“…We found the incidence of vomiting to be similar in both groups: 16.7% in the aminophylline group and 14.6% in the caffeine group. Vomiting in methylxantine-treated patients may be caused by a decrease of lower esophageal sphincter function, 14 gastric acid stimulation, and lower GABA activity. 4 Further assessment is needed as to whether vomiting is a major side effect of therapy, or a frequently-occurring physiological event in premature infants.…”