To evaluate the effect of Face mask ventilation or High flow nasal oxygen on gastric volume during anaesthesia induction in patients undergoing Laparoscopic surgery

. A high inspiratory pressure is known to cause gastric insufflation during facemask ventilation. Therefore, the effect   HFNO can be compared as an alternative to facemask on gastric volume. However, in patients undergoing laparoscopic surgery, the increase in gastric volume is a common concern of anaesthesiologists and surgeons. Gastric insufflation may affect the surgical visual field, prolong the operation time and also cause gastric contents regurgitation, aspiration pneumonitis and stomach perforation, Distension of the gastric antrum triggers a para-sympathetic reflex that results in increased secretions of gastric acid, thereby increasing the mortality risk. In previous studies, the occurrence of gastric insufflation was determined by auscultation with a stethoscope over the epigastrium; however, the reliability and accuracy of this method are uncertain. With abdominal ultrasound, we can detect the excessive presence of air in the stomach and accurately estimate the gastric volume through the measurement the gastric antral cross-sectional area (CSA).