Safety Of Rapid Induction With Preoxygenated Non-positive Pressure Ventilation In Laparoscopic Surgery Under General Anesthesia

Objective:General anesthesia with endotracheal intubation is the main anesthetic method for laparoscopic surgery.In clinic,a closed facemask is commonly used to give positive pressure ventilation to patients with respiratory depression during induction,so as to avoid hypoxia and carbon dioxide retention.However,positive pressure ventilation may cause gas to enter the patient’s stomach.It not only increases the risk of reflux and aspiration,but also is not conducive to the exposure of surgical visual field and surgical operation.Anesthesiologists often use Sellick’s manipulation for oppressing cricoid cartilage,or jaw-lift technique,as well as oppressing upper abdomen,to reduce gastric insufflation,thus reduce the risk of reflux and aspiration.Although these methods are effective to some extend,they are not as effective as rapid induction with preoxygenated non-positive pressure ventilation.Rapid induction with preoxygenated non-positive pressure ventilation is a common method of general anesthesia for patients with full stomach in emergency,which can greatly reduce the risk of reflux and aspiration.However,its routine application in laparoscopic surgery is still less,mainly concerning of its safety.Therefore,we will explore the safety of rapid induction with preoxygenated non-positive pressure ventilation in laparoscopic surgery under general anesthesia through a prospective study.Methods:According to the inclusion and exclusion criteria,99 patients who underwent regular laparoscopic surgery in Nanfang Hospital from July 2019 to December 2019 were randomly divided into three groups:manual positive pressure ventilation group(Group A),pressure controlled positive pressure ventilation group(Group B)and non-positive pressure ventilation group(Group C).All patients were preoxygenated for 3 minutes before induction and were quickly induced by propofol and rifen through dual-channel target-controlled injection.Different auxiliary ventilation strategies were implemented in three groups.Intubation was carried out one minute after muscle relaxant(rocuronium)was injected.Blood gas was taken before preoxygenation(t0),after preoxygenation(t1),when consciousness disappeared(t2),when endotracheal intubation(t3),and when endotracheal intubation finished(t4).The blood gas assay values(PaO2、PaCO2、pH、HCO3-)and basic vital signs(HR、MAP、SpO2)were recorded and compared among the three groups at each time point.Gastric insufflation score and the incidence of inwelling gastric tube,vomiting,cough,reflux and aspiration were compared among the three groups.Results:At t3 and t4,the PaO2 and pH in Group C was lower than that in Group A and Group B(P<0.05),and the PaCO2 of Group C was higher than that in Group A and Group B(P<0.05).When endotracheal intubation finished(t4),the MAP of the three groups was lower than that of t0(P<0.05),but there was no significant difference of the HR among the three groups(P>0.05).SpO2,PaO2 and PaCO2 at t4 increased significantly than that at t0 in the three groups(P<0.05).pH at t4 was lower than that at t0 in the three groups(P<0.05),while HCO3-increased only in Group C(P<0.05).There was no significant difference in HR,MAP,SpO2 and HCO3-among the three groups at the same time(P>0.05).There were no adverse events such as reflux,vomiting and aspiration in the three groups.The gastric insufflation score in Group A and Group B was higher than that in Group C(P<0.05),and the cases of inwelling gastric tube were also more than that in Group C(P<0.05).Conclusion:Rapid induction with preoxygenated non-positive pressure ventilation can reduce the occurrence of gastric insufflation.After endotracheal intubation,PaO2 and pH is lower while PaCO2 is higher than that of manual and pressure-controlled ventilation,but both are still within the safe allowable range.The vital signs is not affected.So it is safe and effective in laparoscopic surgery under general anesthesia.