Objective  The aim of this study was to observe the effect of carbohydrate consumption 2hours before surgery on the gastric volume of elderly patients undergoing gastrointestinal surgery with the technique of point-of-care gastric ultrasound, and further assess the risk of reflux misabsorption.

  Methods  Elderly patients (> 65 years) undergoing abdominal operation were prospectively recruited in Sichuan Provincial People's Hospital between December 2017 and October 2018 and were randomly divided into experimental and control groups.The patients in the experimental group fasted for 8 hours and drank 200 ml carbohydrate 2 hours before surgery; those in the control group were required of 8-hour food fasting and 4-hour liquid fasting before the operation. The gastric antrum of each patient was scanned in the position of 45° semi-sitting and right lateral decubitus. The anterior-posterior diameter and cranial-caudal diameter of the gastric antrum were measured at the above two positions before induction of anesthesia.Then the distal cross-sectional area (CSA), gastric volume (GV), and gastric volume/weight (GV/W) were calculated. Correlation of the semi-quantitative GV score and GV/W grading with the risk of reflux misaspiration were assessed.

  Results  A total of 69 patients meeting the inclusive and exclusive criteria were enrolled in this study, 33 in the experimental group and 36 in the control group. The two groups showed similar demographic characteristics, surgical category, and classification of the American Society of Anesthesiologists (all P>0.05). In the semi-sitting position, the GV/W was (0.57±0.23)ml/kg and (0.44±0.21)ml/kg in the experimental and the control groups, respectively; in the right lateral decubitus position, CSA was (578.8±71.5)mm² in the experimental group vs. (513.3±53.2)mm² in the control group, GV(21.2±11.1)ml vs. (12.9±6.8)ml, GV/W(0.36±0.17)ml/kg vs. (0.20±0.11)ml/kg, respectively; the above all showed statistically significant between the two groups (all P < 0.05). The semi-quantitative GV score showed 0 in 17 patients(51.5%, 17/33), 1 in 15(45.5%, 15/33), 2 in 1(3.0%, 1/33) in the experimental group and 0 in 25(69.4%, 25/36), 1 in 11(30.6%, 11/36), 2 in 0(0, 0/33) in the control group (P>0.05). The risk assessment of reflux misabsorption showed that very low risk was 81.8%(27/33) in the experimental group vs. 94.4%(34/36) in the control group, low risk 18.2%(6/33) vs. 5.6%(2/36), and no high risk in both groups (P > 0.05).

  Conclusion  Although preoperative carbohydrate consumption might increase the GV in elderly patients with gastrointestinal surgery, the risk of reflux misabsorption does not increase.