Gastric emptying of a carbohydrate-electrolyte solution in healthy volunteers depends on osmotically active particles

Preoperative ingestion of only clear fluids until 2 hours before induction of anesthesia is a common preoperative fasting regimen. Gastric emptying times, however, vary among clear fluids. We therefore investigated the gastric emptying of 2 clear glucose-electrolyte drinks.

A 2-way crossover study was performed in 10 healthy volunteers. After fasting, the volunteers drank 500 mL of either OS-1(®), an oral rehydration solution, or Pocari Sweat(®), a popular sports drink, over 3 minutes in a standing position. Magnetic resonance imaging was performed before, immediately after, and 30 minutes after the drinking of each test fluid. The difference in gastric emptying between OS-1(®) and Pocari Sweat(®) was evaluated by comparing gastric fluid volume, flow rate, and residual ratio. We also compared the flow rates of sodium, potassium, carbohydrates, and osmotically active particles in the 2 test fluids.

Gastric fluid volume 30 minutes after drinking was significantly smaller for OS-1(®) (76.0 ± 57.0 mL) than for Pocari Sweat(®) (158.1 ± 73.5 mL, p<0.01), although the volumes did not differ before or immediately after drinking. The flow rate was significantly faster for OS-1(®) (10.66 ± 3.34 mL) than for Pocari Sweat(®) (8.68 ± 3.02 mL/min, p<0.05), and the residual ratio was significantly smaller for OS-1(®) (21 ± 14% than for Pocari Sweat(®) (41 ± 19%, p<0.01). The flow rates of sodium, potassium, and glucose differed significantly between OS-1(®) and Pocari Sweat(®), whereas the flow rate of osmotically active particles did not.

Gastric emptying is significantly faster for OS-1(®) than for Pocari Sweat(®).