The Effect Of Head Rotation On Gastric Insufflation In Patients Undergoing Laparoscopic Cholecystectomy During Induction Of Anaesthesia Detected By Ultrasound

Background: Facemask ventilation is the essential technique during induction of anesthesia.Facemask ventilation must ensure effective ventilation and avoiding gastric insufflflation at the same time.Insufflation of gas into the stomach may elevate intragastric pressure,thus increasing the risk for regurgitation of gastric contents and pulmonary aspiration.Studies had shown that head rotation can improve the efficiency of mask ventilation.In this study we investigated the influence of head rotation on gastric insufflflation during anesthetic induction in paralysed adults.Methods: Ninety patients who were scheduled undergoing laparoscopic cholecystectomy under general anesthesia were randomly divided into Group N and Group R.In Group N,the mask ventilation was performed with a neutral head position,In Group R,the mask ventilation was performed with a head position rotated45° to the right.Facemask ventilation was lasted for 3 mintues with volume controlled mode at 8 ml/kg,the cross-sectional area of gastric antrum was measured before and after mask ventilation.The primary outcome was antral cross-sectional area before and after mask ventilation.Secondary outcomes included the incidence of gastric insufflation detected by ultrasound,gastric insufflation evaluated using direct vision of laparoscopy,as well as respiratory parameters(PEAK,PETCO2)at 180 seconds after mask ventilation.Other outcomes included the incidence of nausea and vomiting in the 24 postoperative hours,the recovery time of gastrointestinal function and hospitalization days.Results: A total of 82 patients were enrolled and evaluated,there were no significant differences in patients’ characteristics between the two groups.No difference was observed in the baseline antral cross-sectional area between the two groups(P=0.171),the antral cross-sectional area in group R was lower in comparison with Group N after facemask ventilation(P=0.002).There was no significant difference in the incidence of gastric insufflation detected by ultrasound as well as respiratory parameters between the two groups.There were no statistically significant differences in the incidence of postoperative nausea and vomiting,the recovery time of gastrointestinal function and hospitalization days between the two groups((P>0.005).Conclusion: Under a volume controlled ventilation of 8 ml/kg,facemask ventilation with a head rotation of 45°decreased gastric insufflation during anesthesia induction in laparoscopic cholecystectomy.But no differences were found in other outcomes between the two groups.This result suggests that both neutral head position and head rotation of 45° can be safety used after anaesthesia induction during FMV.