Abstract
Introduction: Gastric residual volume (GRV,>150 ml/kg) can increase the risk of aspiration during general anesthesia (GA). This study aimed to compare GRV and gastric pH in patients admitted for GA who had taken 150 ml of clear fluids 1 and 2 hour (h) prior to surgery.
Methods: This study was conducted among 81 American Society of Anesthesiologists I and II patients aged 18-65 years who underwent elective surgeries under GA. After randomization, the patients were divided into two groups to receive either 150 ml of non-caloric clear fluids 1 or 2 h prior to induction. Gastric volume using sonographic measurement of antral cross-sectional area (CSA), gastric pH, postoperative nausea and vomiting (PONV), and patient satisfaction (Numerical Rating Scale) were assessed. Data was analyzed with an independent t-test, and a Mann-Whitney U test with significance at P<0.05.
Results: Antral CSA was comparable between groups. GRV (ml) was significantly higher in the 1 h group than in the 2 h group. The mean GRV indexed to body weight (ml/kg) was 0.840 (0.381) in the 1h group and 0.634 (0.389) in the 2h group. Gastric pH, PONV, and patient satisfaction in 1h group was comparable with 2h group.
Conclusion: The GRV assessed by ultrasonography in patients after 1h of fasting to 150 ml of clear fluids is more than that of 2h fasting, though it did not increase the risk of aspiration as the volume was less than 1.5ml/kg. This demonstrates the safety of clear fluids till 1h prior to general anesthesia.