A COMPARISON OF THE VOLUME AND ON OF GASTRIC CONTENTS OF OBESE AND LEAN SURGICAL PATIENTS

Obese surgical patients are typically considered to be more Likely tha n lean patients to possess high-volume and low-pH (HVLP) gastric conte nts after a standard preoperative fast based on a study of a populatio n predominately consisting of patients receiving intramuscular preoper ative sedation. We revisited this issue in a study population of 256 f asted 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 withdra wn. Subjects' gastric contents were defined as HVLP if they exhibited a combination of a volume >25 mt and a pH <2.5. Obesity was defined as a body mass index >30. Among nonmedicated obese patients, the proport ion 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 d ifference between the HVLP proportions for these two groups was found to be significant (P < 0.05) using chi(2) analysis. Obesity seems to b e associated with a significantly decreased risk of HVLP gastric conte nts among surgical patients with no history of gastroesophageal pathol ogy after a normal interval of preoperative fasting. Implications: Pre vious studies have shown that obese surgical patients have a greater v olume 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 wi th lean patients.