Comparison of Preoperative Assessment of Gastric Volume and pH in Patients Undergoing Elective Surgery with Prior Two Hour Fasting versus Overnight FastingA Randomised Clinical Trial

Abstract

Introduction: Aspiration of gastric content is a known lifethreatening, yet preventable complication of anaesthesia. While mostly all elective procedures do follow the preoperative fasting protocols as recommended by American Society of Anaesthesia (ASA), there are many situations where the fasting guideline cannot be followed considering the emergency. In such cases, bedside ultrasound assessment of gastric volume can become an important tool to stratify aspiration related risk. Aim: To find out the actual trends of gastric volume and pH in patients with two hour fasting with a prokinetic drug versus overnight fasting who are undergoing elective procedures. Materials and Methods: This single centre, randomised clinical trial was conducted in the Department of Anaesthesia at Dr. Sampurnanand Medical College, Jodhpur, Rajasthan, India, between December 2020 and July 2021, among 50 patients of ASA grade I undergoing elective procedures under general anaesthesia. Participants were divided into two groups. Group A patients were advised overnight fasting while group B participants were advised two hour fasting for clear liquids followed by intravenous (i.v.) metoclopramide injection. Assessment of gastric volume and other gastric parameters were done using a portable ultrasound machine. The pH of gastric content was measured using pH strips. Gastric content was obtained using Ryle’s Tube placed in the patient, postinduction of anaesthesia. Collected data was statistically analysed using Unpaired t-test for all qualitative data. Results: Significant difference in the anteroposterior diameter (3.46±0.34 in group A versus 2.24±0.30 in group B), cranio-caudal diameter (4.77±0.51 in group A versus 3.71±0.36 in group B), antral curved surface area (9.90±0.77 in group A versus7.77±1.04 in group B) and gastric volume (127.48±13.09 in group A versus 104.65±15.43 in group B) and pH (2.08±0.28 in group A versus 2.80±0.41 in group B) was observed (p-value=0.0001). However, no significant difference in any gastric parameter, mentioned above, was noted before and after injecting intravenous metoclopramide. Conclusion: Bedside ultrasound assessment of gastric volume is an important toolfor aspiration risk stratification especially in emergency, non-fasting patients.