Mechanisms of gastroesophageal reflux in children with sequelae of birth asphyxia

Patterns of childhood gastroesophageal reflux (GER) have been studied extensively; however, the mechanisms underlying its occurrence in neurologically impaired children (NIC) are poorly understood. Concurrent esophageal manometry and pH monitoring was conducted in 10 un-operated children (7 male; mean age: 59.5 months) with sequelae birth asphyxia and esophagitis. Reflux episodes were scored when esophageal pH decreased to <4 for at least 5 s. When the rate of decrease of lower esophageal sphincter (LES) pressure was >1 mm Hg/s, the decrease of LES pressure was defined as LES relaxation. The time relationship of the pharyngeal manometric swallowing signal to LES relaxation onset was then evaluated in order to distinguish between LES relaxations associated with swallowing (type II or III, associated with one or more swallows, respectively) and those that occurred independently of swallowing (type I). Results: Esophageal manometry and pH monitoring were conducted for a mean duration of 91.5 min. Basal LES pressure averaged (±SD) 9.2 ± 4.8 mm Hg; in 4 of 10 patients (40%) the LES pressure was largely undetectable, varying between 0 and 2 mm Hg. Mean LES pressure was inversely correlated with age (r = 0.7, P = 0.02). The total number of reflux episodes/h averaged 32.1 ± 12.1 LES pressure reached 0 mm Hg in 98% of reflux episodes. Type I LES relaxations were present in 3.15 ± 1.1 reflux episodes/h, whereas type II LES relaxation occurred in 2.3 ± 2.4 episodes/h. Acid reflux episodes appeared during absent basal LES tone periods, without phasic LES relaxations, in 74%. Conclusions: Absent basal LES tone is the main mechanism of GER in a subgroup of NIC, especially in older children. Transient LES relaxation, the most common known event associated with acid reflux in neurologically normal children, seems to precede a minority of reflux events in NIC.