title: Effects of different respiratory maneuvers on esophageal sphincters in obese patients before and during anesthesia.
abstract: BACKGROUND
  Data on esophageal sphincters in obese individuals during anesthesia are sparse. The aim of the present study was to evaluate the effects of different respiratory maneuvers on the pressures in the esophagus and esophageal sphincters before and during anesthesia in obese patients.
  
  
  METHODS
  Seventeen patients, aged 28-68 years, with a BMI ≥ 35 kg/m², who were undergoing a laparoscopic gastric by-pass surgery, were studied, and pressures from the hypopharynx to the stomach were recorded using high-resolution solid-state manometry. Before anesthesia, recordings were performed during normal spontaneous breathing, Valsalva and forced inspiration. The effects of anesthesia induction with remifentanil and propofol were evaluated, and positive end-expiratory pressure (PEEP) 10 cmH₂O was applied during anesthesia.
  
  
  RESULTS
  During spontaneous breathing, the lower esophageal sphincter (LES) pressure was significantly lower during end-expiration compared with end-inspiration (28.5 ± 7.7 vs. 35.4 ± 10.8 mmHg, P<0.01), but barrier pressure (BrP) and intra-gastric pressure (IGP) were unchanged. LES, BrP (P<0.05) and IGP (P<0.01) decreased significantly during anesthesia. BrP remained positive in all patients. IGP increased during Valsalva (P<0.01) but was unaffected by PEEP. Esophageal pressures were positive during both spontaneous breathing and mechanical ventilation. Esophageal pressures increased during PEEP from 9.4 ± 3.8 to 11.3 ± 3.3 mmHg (P<0.01).
  
  
  CONCLUSIONS
  During spontaneous breathing, the LES pressure was the lowest during end-expiration but there were no differences in BrP and IGP. LES, BrP and IGP decreased during anesthesia but BrP remained positive in all patients. During the application of PEEP, esophageal pressures increased and this may have a protective effect against regurgitation.
authors.affiliation: Department of Anesthesia and Intensive Care, Örebro University Hospital, Sweden. alex.deleon@orebroll.se
authors.forename: A
authors.initials: A
authors.lastname: de Leon
authors.forename: S-E
authors.initials: SE
authors.lastname: Thörn
authors.forename: M
authors.initials: M
authors.lastname: Raoof
authors.forename: J
authors.initials: J
authors.lastname: Ottosson
authors.forename: M
authors.initials: M
authors.lastname: Wattwil
mesh_terms: D000328:Adult; D000368:Aged; D000758:Anesthesia; D001794:Blood Pressure / Q000502:physiology; D015992:Body Mass Index; D002404:Catheterization; D056805:Consciousness Monitors; D004562:Electrocardiography; D049630:Esophageal Sphincter, Lower / Q000502:physiology*; D049631:Esophageal Sphincter, Upper / Q000502:physiology*; D005260:Female; D015390:Gastric Bypass; D006801:Humans; D010535:Laparoscopy; D008297:Male; D008365:Manometry; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology*; D010092:Oximetry; D011175:Positive-Pressure Respiration; D011312:Pressure; D013270:Stomach / Q000502:physiology; D016683:Supine Position / Q000502:physiology; D014636:Valsalva Maneuver