title: Role of the lower esophageal sphincter on esophageal acid exposure - a review of over 2000 patients.
abstract: OBJECTIVE
  Three lower esophageal sphincter (LES) characteristics associated with gastro-esophageal reflux disease (GERD) are, LES pressure = 6 mmHg, abdominal length (AL) <1 cm and overall length (OL) <2 cm. The objective of this study was to validate this relationship and evaluate the extent of impact various LES characteristics have on the degree of distal esophageal acid exposure.
  
  
  METHODS
  A retrospective review of a prospectively maintained database identified patients who underwent esophageal manometry and pH studies at Creighton University Medical Center between 1984 and 2008. Patients with esophageal body dysmotility, prior foregut surgery, missing data, no documented symptoms or no pH study, were excluded. Study subjects were categorized as follows: (1) normal LES (N-LES): patients with LES pressure of 6-26 mmHg, AL = 1.0 cm and OL = 2 cm; (2) incompetent LES (Inc-LES): patients with LES pressure <6.0 mmHg orAL <1 cm or OL <2 cm; and (3) hypertensive LES (HTN-LES): patients with LES pressure >26.0 mmHg with AL = 1 cm and OL = 2 cm. The DeMeester score was used to compare differences in acid exposure between different groups.
  
  
  RESULTS
  Two thousand and twenty patients satisfied study criteria. Distal esophageal acid exposure as reflected by the DeMeester score in patients with Inc-LES (median=20.05) was significantly higher than in patients with an N-LES (median=9.5), which in turn was significantly higher than in patients with an HTN-LES. Increasing LES pressure and AL provided protection against acid exposure in a graded fashion. Increasing number of inadequate LES characteristics were associated with an increase both in the percentage of patients with abnormal DeMeester score and the degree of acid exposure.
  
  
  CONCLUSIONS
  LES pressure (=6 mmHg) and AL (<1 cm) are associated with increased lower esophageal acid exposure, and need to be addressed for definitive management of GERD.
authors.affiliation: Department of Surgery, Creighton University Medical Center, Omaha, Nebraska 68131, USA.
authors.forename: Kazuto
authors.initials: K
authors.lastname: Tsuboi
authors.forename: Masato
authors.initials: M
authors.lastname: Hoshino
authors.forename: Abhishek
authors.initials: A
authors.lastname: Sundaram
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Yano
authors.forename: Sumeet K
authors.initials: SK
authors.lastname: Mittal
mesh_terms: D000328:Adult; D049630:Esophageal Sphincter, Lower / Q000033:anatomy & histology* / Q000503:physiopathology*; D050782:Esophageal pH Monitoring; D005260:Female; D005764:Gastroesophageal Reflux / Q000209:etiology*; D006801:Humans; D008297:Male; D008365:Manometry; D008875:Middle Aged