Effect Of Different Mask Ventilation Pressure On Gastric Intake In The Elderly Patients With General Anesthesia Induced By Mask Ventilation

Objective The use of ultrasound technology real-time monitoring of gas in the antrum and observe the effects of different masks ventilation on gas in the stomach caused by facemask ventilation(FMV)in elderly patients with muscular relaxation of general anesthesia,and to explore ways to reduce gastric Ventilation within the appropriate mask ventilation pressure.Methods From February to November 2017,160 patients undergoing elective general anesthesia were recruited in the Second Hospital of Ningbo City.Aged 65 to 80 years old,the American Society of Anesthesiologists(ASA)graded I or II,body mass index(BMI)<30kg / m2.According to the mask ventilation pressure,the rats were randomly divided into 4 groups(n = 40): P8 group(8 cm H2O),P10 group(10 cm H2O),P12 group(12 cm H2O)and P14 group(14 cm H2O).Patients were induced with general anesthesia with propofol,remifentanil and rocuronium followed by mask ventilation in a pressure-controlled mode.Ultrasound was used to observe the gas in the antral area of the patient in real time.The cross-sectional antral area(CSA),the presence or absence of air in the stomach,the measured tidal volume(Vt)at the end of mask ventilation,and the end-tidal oxygen concentration(Et O2)were recorded before and after ventilation.Results The incidence of gastric aspiration in the 4 groups was 7.5%,32.5%,55% and 75%,respectively.There were significant differences between P8 group and P10 group(χ2 = 7.813,P <0.01),P10 group and P12 group(χ2 = 4.114,P <0.05)The difference was not statistically significant.After the mask was ventilated,CSA of gastric antrum in P10,P12 and P14 groups increased significantly(t = 2.419,5.644,7.173,P <0.05),and there was no significant change in mask group P8 before and after ventilation(t = 0.128,P> 0.05).Compared with P12 group,the CSA of gastric antrum in P10 group decreased significantly and the P14 group increased significantly(all P <0.01).At the end of mask ventilation,the tidal volume of each group had statistical difference(all P <0.001),in which the Vt of P8 and P10 was less than 6ml / kg,which was the lack of mask ventilation.At the end of mask ventilation,there was a statistically significant difference(all P <0.001)between Et O2 in each group.Conclusion For senile patients with generalized anesthesia,a 12 cm H2 O mask ventilation pressure provides a balance between reducing gastric aspiration and effective pulmonary ventilation.