title: Relationship between straining, transient lower esophageal sphincter relaxation, and gastroesophageal reflux in children.
abstract: OBJECTIVE
  Physical straining such as deep inspiration or coughing may induce gastroesophageal reflux (GER) by overcoming feeble lower esophageal sphincter (LES) pressure. The role of straining as a provocant of GER has not been analyzed systematically in children. It was our aim to examine the contribution of straining to the occurrence of GER with particular attention to its relationship to transient LES relaxations, which are a major mechanism of the occurrence of GER in pediatric patients.
  
  
  METHODS
  Concurrent esophageal manometry and pH monitoring was performed for 4 h postprandially in six children with esophagitis (age 9 months to 12 yr). Analysis was performed on isolated single strain episodes, defined as an increased intragastric pressure > 10 mm Hg. When a drop of esophageal pH < 4.0 was noted within 15 sec after any part of a strain, this strain was defined as related to the reflux episode.
  
  
  RESULTS
  The median value of basal LES pressure was 10 mm Hg (range 1-18). In all, 134 analyzable strains and 87 analyzable reflux episodes were recorded. Isolated strains were associated with 20 reflux episodes (23%). Reflux was observed more frequently with strains that occurred during transient LES relaxations (12/40) than straining when the LES was contracted (8/94) (p < 0.01). Sustained strain (35%) and inspiratory strain (25%) were the major patterns of straining related to reflux.
  
  
  CONCLUSIONS
  Straining provoked reflux infrequently and simultaneous occurrence of straining and transient LES relaxation was important in determining the occurrence of strain-related reflux in pediatric patients with reflux esophagitis.
authors.affiliation: Department of Pediatric Surgery, Osaka University Graduate School of Medicine, Suita, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kawahara
authors.forename: J
authors.initials: J
authors.lastname: Dent
authors.forename: G
authors.initials: G
authors.lastname: Davidson
authors.forename: A
authors.initials: A
authors.lastname: Okada
mesh_terms: D002648:Child; D002675:Child, Preschool; D003371:Cough / Q000150:complications; D004943:Esophagogastric Junction / Q000503:physiopathology*; D004947:Esophagus / Q000737:chemistry; D005764:Gastroesophageal Reflux / Q000209:etiology* / Q000503:physiopathology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007223:Infant; D008365:Manometry; D011312:Pressure; D012119:Respiration