title: Validation of a mathematical model for ultrasound assessment of gastric volume by gastroscopic examination.
abstract: BACKGROUND
  Pulmonary aspiration of gastric contents is a serious perioperative complication. Previous models of ultrasound gastric volume assessment are preliminary and have not been validated by an external "gold standard." In the present study we propose a more accurate model based on prospective data obtained from 108 patients undergoing bedside gastric sonography and upper gastrointestinal endoscopy (UGE).
  
  
  METHODS
  Patients undergoing elective UGE were randomized to ingest one of 6 predetermined volumes of apple juice after an 8-hour fasting period. A cross-sectional area of the antrum in the right lateral decubitus position (Right lat CSA) was measured by a blinded sonographer following a standardized scanning protocol. Gastric fluid was subsequently suctioned under gastroscopic vision during UGE performed by a blinded gastroenterologist and measured to the nearest milliliter.
  
  
  RESULTS
  Data from 108 patients suggest that a previously reported model tends to overestimate gastric volume particularly at low volume states. A new best fit mathematical model to predict gastric fluid volume based on measurements of Right lat CSA is presented. This new model built on a more accurate gold standard can be used to estimate gastric volumes from 0 to 500 mL, in nonpregnant adults with body mass index<40 kg/m2.
  
  
  CONCLUSIONS
  We report a new prediction model to assess gastric fluid volume using standard 2-dimentional bedside ultrasound that has several advantages over previously reported models.
authors.affiliation: University Health Network, University of Toronto, Toronto Western Hospital, Department of Anesthesia, 399 Bathurst St. Toronto, Ontario, M5T 2S8, Canada. anahi.perlas@uhn.on.ca
authors.forename: Anahi
authors.initials: A
authors.lastname: Perlas
authors.forename: Nicholas
authors.initials: N
authors.lastname: Mitsakakis
authors.forename: Louis
authors.initials: L
authors.lastname: Liu
authors.forename: Maria
authors.initials: M
authors.lastname: Cino
authors.forename: Nidhi
authors.initials: N
authors.lastname: Haldipur
authors.forename: Liisa
authors.initials: L
authors.lastname: Davis
authors.forename: Javier
authors.initials: J
authors.lastname: Cubillos
authors.forename: Vincent
authors.initials: V
authors.lastname: Chan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019412:Anatomy, Cross-Sectional; D005260:Female; D005773:Gastroscopy / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D011446:Prospective Studies; D015203:Reproducibility of Results; D018401:Sample Size; D013270:Stomach / Q000000981:diagnostic imaging*; D013396:Suction; D016683:Supine Position; D014463:Ultrasonography; D055815:Young Adult