Preoperative Fasting of Eight Hours Provide Better Gastric Emptying: Ultrasound Assessment of Gastric Volume

Preoperative fasting is a common practice to decrease perioperative aspiration risk. The American Society of Anesthesiologists (ASA) recommends preoperative fasting of 8 hours after a full meal. ASA preoperative fasting recommendation is based on the Western diet. A typical Western diet has a higher fat content than Asian standard solid meals. This study aimed to analyze intragastric volume with ultrasound after 6-hour and 8-hour fasting after an Asian traditional solid meal.

This cohort study recruited 37 subjects from January to February 2019. Subjects were patients scheduled for elective non-digestive surgery and planned for preoperative fasting of 8 hours. Before preoperative fasting, all subjects consumed standard Asian meals. We performed an ultrasound of the gastric antrum during the relaxation phase after two contractions. After a good image was acquired, the cross-sectional area and gastric volume (GV) were calculated. GV was grouped based on a border value of 1.5 mL/kg.

GV 6 hours after solid intake was 30.93 (1.60-205.25) mL, and GV 8 hours after solid intake was 16.34 (0.73-62.49) mL (P = 0.002). After 6 hours, 5.4% of the subjects had a GV above 1.5 mL/ kg, while after fasting for 8 hours, the GV of all subjects was below 1.5 mL/kg. Age was correlated moderately and negatively with the GV of 6 hours and 8 hours fasting (P < 0.001, correlation coefficient = -0.610, and P < 0.001, correlation coefficient = -0.580).

Intragastric volume 8 hours after a standard Asian meal intake was lower than 6 hours after a traditional Asian meal.