Gastric emptying time of oligomeric formula in adult males

Background: We conducted two clinical studies on the gastric emptying time of oligomeric formula in men to help estimate safe preoperative fasting times in patients receiving enteral nutrition.Methods: In Study 1, 10 adult male volunteers orally ingested fat-free oligomeric formula and a clear fluid on different days. The cross-sectional area (CSA) of the gastric antrum was measured by abdominal ultrasonography in the right lateral decubitus position every hour until the area was ≤ 4.0 cm2, or up to 4 h after ingestion.In Study 2, 6 adult male volunteers orally ingested fat-containing oligomeric formula, a clear fluid, and rice balls on different days. The CSA was measured every hour until the area was ≤ 4.0 cm2, or up to 6 h after ingestion.Results: In Study 1, gastric emptying time was longer for fat-free oligomeric formula (3.5 [3-4] h) than for clear fluid (1 [1-2] h) (p < 0.0001). In Study 2, gastric emptying time was not statistical different between fat-containing oligomeric formula (4.5 [3-5] h) and rice balls (4 [4-4.25] h), and the times were longer for both of these than for clear fluid (1.5 [1-2] h) (p < 0.0001). Gastric emptying time never exceeded 4 h after ingestion of fat-free oligomeric formula or 5 h after ingestion of fat-containing oligomeric formula or rice balls.Conclusions: Gastric emptying time appears to be approximately 4 h for fat-free oligomeric formula and about 5 h for fat-containing oligomeric formula, which may be comparable to the time of rice balls.