title: Transdiaphragmatic pressure gradients and the lower esophageal sphincter after tight abdominal wall plication in the rat.
abstract: BACKGROUND
  Gastroesophageal reflux (GER) is increasingly recognized as a complication of surgical closure of gastroschisis and omphalocele.
  
  
  OBJECTIVE
  This study tests the hypothesis that forceful abdominal wall closure reinforces the transdiaphragmatic pressure gradients that constitute the main GER-driving force and challenges the antireflux barrier.
  
  
  METHODS
  Abdominal and esophageal pressures as well as lower esophageal sphincter pressures (LESP) and length (LESL) were measured in 17 adult rats before tight abdominal wall plication, after it, and 1 week later.
  
  
  RESULTS
  This maneuver increased the transdiaphragmatic expiratory gradient from 0.67 +/- 1.31 to 6.97 +/- 2.68 mm Hg (P < .01) and the inspiratory gradient from 4.36 +/- 1.13 to 10.79 +/- 2.31 mm Hg (P < .01) by markedly increasing both the expiratory (from 1.47 +/- 0.74 to 9.44 +/- 1.85 mm Hg; P < .01) and inspiratory (from 0.98 +/- 0.69 to 6.83 +/- 1.55 mm Hg; P < .01) intraabdominal pressures. These changes were transient, and all pressures became normal after 1 week. The antireflux barrier functioned properly under these new conditions because both LESP and the diaphragmatic pinch-cock pressure (DPP) increased, from 20.3 +/- 3.63 to 26.5 +/- 4.31 mm Hg (P < .01) and from 16.4 +/- 7.25 to 22.5 +/- 4.36 mm Hg (P < .01), respectively, while LESL remained unchanged.
  
  
  CONCLUSIONS
  Tight abdominal wall plication in the rat generates high intraabdominal pressures and thus reinforces the transdiaphragmatic pressure gradients, but these conditions elicit a healthy barrier response with sphincteric reinforcement. In addition, these changes are transient and fade out some time after operation. These facts should be taken into account for understanding the pathogenesis of GER after repair of abdominal wall defects in human babies.
authors.affiliation: Department of Pediatric Surgery, Hospital Infantil Universitario La Paz, Madrid, Spain.
authors.forename: B
authors.initials: B
authors.lastname: Qi
authors.forename: J A
authors.initials: JA
authors.lastname: Diez-Pardo
authors.forename: C
authors.initials: C
authors.lastname: Soto
authors.forename: J A
authors.initials: JA
authors.lastname: Tovar
mesh_terms: D000009:Abdominal Muscles / Q000601:surgery*; D000818:Animals; D003964:Diaphragm / Q000502:physiology*; D004943:Esophagogastric Junction / Q000502:physiology*; D005764:Gastroesophageal Reflux / Q000209:etiology; D006801:Humans; D008297:Male; D008365:Manometry; D011183:Postoperative Complications / Q000209:etiology; D051381:Rats; D017208:Rats, Wistar; D013536:Suture Techniques