Key result
Obesity linked to a ~37% lower incidence of high-volume, low-pH gastric contents versus lean patients.
Why the study?
Obese surgical patients are typically considered more likely than lean patients to have high-volume and low-pH gastric contents after fasting, but prior studies included patients receiving preoperative sedation.
Does obesity increase the risk of high-volume and low-pH gastric contents in fasted surgical patients compared to lean patients?
Observational (n=256)
Does obesity increase the risk of high-volume and low-pH gastric contents in fasted surgical patients compared to lean patients?
Absolute Event Rate: 26.6% vs 42%
p-value: p=< 0.05
Contrary to previous assumptions, fasted obese surgical patients have a significantly lower incidence of high-volume, low-pH gastric contents compared to lean patients.
Challenges assumption of high aspiration risk in fasted obese patients; leaves open whether modern protocols alter gastric content profiles.
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 Immediately after endotracheal intubation, an 18-French sump tube was placed, and gastric contents were withdrawn.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 squared 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. Implications: 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.
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Harter et al. (1998) conducted an observational in Fasted surgical patients (n=256). Obesity (BMI >30) vs. Lean patients was evaluated on High-volume (>25 mL) and low-pH (<2.5) gastric contents (p=< 0.05). Obesity (BMI >30) was associated with a significantly lower incidence of high-volume, low-pH gastric contents compared to lean patients (26.6% vs 42.0%; P<0.05) after a preoperative fast.
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