Clinical Study Of Different Modes Of Mask Ventilation On Gastric Air Intake And Regurgitation Risk In Gynecological Laparoscopic Surgery Patients

Objective:To observe the changes of gastric antrum cross-sectional area（CSA）in patients taking gynecological laparoscopic surgery during anesthesia induction with pressure-controlled ventilation-volume guaranteed（PCV-VG）,pressure controlled ventilation（PCV）and non-positive pressure ventilation.At the same time,to analyze the safety and efficacy of preoxygenation without positive pressure ventilation during anesthesia induction.And to evaluate the effectiveness of different mask ventilation modes on postoperative flatulence,nausea and vomiting after gynecological laparoscopic surgery.This study will provide ideas for appropriate mask ventilation mode during the induction under general anesthesia in laparoscopic surgery.Methods:In this randomised controlled trial,we included adult female patients taking optional laparoscopic gynecological surgery.The intaked patients were assigned into three groups stochastically:PCV-VG group（group A）,PCV group（group B）,and non-positive pressure ventilation group（group C）.The three-level grading of gastric contents and the antral cross-sectional area（CSA）was assessed by ultrasound at baseline before mask ventilation,after endotracheal intubation and end of surgery.The main outcome was the occurrence of intragastric air intake.Other outcomes included HR,MAP,Sp O₂ and BIS:before anesthesia induction,after anesthesia induction,the beginning of anesthesia,before mechanical ventilation,after mechanical ventilation.The p H,Pa O₂,Pa CO₂,Sa O₂,Lac,HCO₃^-of arterial blood were recorded before anesthesia induction and after mechanical ventilation.Results:1.The basic information was no significant difference in the three groups（P>0.05）.2.Comparison of the antral CSA:The average CSA was significantly larger in group A and group B at T₀ than that at T₄.Compared with T₄,the mean value CSA of patients in group A and group B was reduced significantly at T₅（P<0.05）.At T₄,the mean value of CSA was significantly larger in group A and group B than group C（4.12?0.40 vs 3.83?0.39,4.05?0.45 vs 3.83?0.39,P values were 0.008 and 0.046,respectively）.3.Risk assessment of reflux:The distribution of 0 points in the semi-quantitative score at T₄ was statistical difference in the three groups（P<0.05）.At T₄,the distribution of very low reflux risk was statistical significance in the three groups（P<0.05）.The incidence of very low reflux risk had increased in group C than that in group A and group B at T₄（P<0.05）.4.Comparison of hemodynamic parameters:Compared with T₀,HR,MAP and BIS in the three groups were decreased at T₂ and T₃（P<0.05）,while Sp O₂ was significantly increased（P<0.05）.Sp O₂ in group A and Group B had significantly increased than that in group C at T₃ and T₄（P<0.05）.Pa O₂ in the three groups were increased at T₄ than that at T₀（P<0.05）.The Pa O₂ and Sa O₂ in group A and group B had significantly increased at T₄ than those in group C,while Pa CO₂ and HCO₃^-were significantly reduced（P<0.05）.5.Postoperative complications:There was no statistical correlation between different mask ventilation modes and nausea,vomiting and flatulence at 2 h and 24 h after operation（all P>0.05）.Conclusion:Compared with pressure-controlled volume-guaranteed ventilation and pressure-controlled ventilation,non-positive pressure ventilation has less effect on gastric volume and can effectively reduce the risk of reflux during induction of general anesthesia in patients undergoing laparoscopic gynecological surgery.For young and middle-aged female patients with ASA I～II and no difficult airway,ventilation without positive pressure mask for a certain period of time during general anesthesia induction did not cause hypoxemia and hypercapnia after 3 minutes of preoxygenation.