title: A comparison of the volume and pH of gastric contents of obese and lean surgical patients.
abstract: Obese surgical patients are typically considered to be more likely than lean patients to possess high-volume and low-pH (HVLP) gastric contents after a standard preoperative fast, based on a study of a population predominately consisting of patients receiving intramuscular preoperative sedation. We revisited this issue in a study population of 256 fasted surgical patients, of which 232 received no preoperative antacid or gastric prokinetic drug. Immediately after endotracheal intubation, an 18-French sump tube was placed, and gastric contents were withdrawn. Subjects' gastric contents were defined as HVLP if they exhibited a combination of a volume > 25 mL and a pH < 2.5. Obesity was defined as a body mass index > 30. Among nonmedicated obese patients, the proportion with HVLP gastric contents was 20 of 75 (26.6%). The proportion of lean patients with HVLP gastric contents was 66 of 157 (42.0%). The difference between the HVLP proportions for these two groups was found to be significant (P < 0.05) using chi 2 analysis. Obesity seems to be associated with a significantly decreased risk of HVLP gastric contents among surgical patients with no history of gastroesophageal pathology after a normal interval of preoperative fasting.
  
  
  CONCLUSIONS
  Previous studies have shown that obese surgical patients have a greater volume of acidic stomach contents than lean patients, despite a routine preoperative fast. We have reexamined this issue and found that among otherwise healthy, fasted, obese surgical patients, there is a lower incidence of combined high-volume, low-pH stomach contents compared with lean patients.
authors.affiliation: Department of Anesthesiology, Ohio State University Hospitals, Columbus 43210, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Harter
authors.forename: W B
authors.initials: WB
authors.lastname: Kelly
authors.forename: M G
authors.initials: MG
authors.lastname: Kramer
authors.forename: C E
authors.initials: CE
authors.lastname: Perez
authors.forename: R R
authors.initials: RR
authors.lastname: Dzwonczyk
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D005260:Female; D005745:Gastric Acidity Determination; D005766:Gastrointestinal Contents; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism*; D011015:Pneumonia, Aspiration / Q000378:metabolism; D013514:Surgical Procedures, Operative