The Relationship Between Gastric Air Intake And Positive Pressure Ventilation During The Period Of Monitoring Anesthesia Induction Real-timely

Objective: Gastric air intake may well happen during the anesthesia induction period in operation.Excessive gas leads to the risks such as patients' lung discomfort and asphyxia.Therefore,reducing the gastric air intake can reduce the operation risks.This paper evaluates the gastric air intake volume by real-timely monitoring the variation of antral area before and after ventilation and assesses the relationship between gastric air intake volume and positive ventilation pressure.We explored the optimal ventilation pressure value under the condition of sufficient oxygen saturation to provide help for clinical anesthesiologists.Method: 89 patients whom Grade 1 and Grade 2 with gynecological surgery in our hospital had been chosen according to the American Association of Anesthesiologists(ASA)grading criteria(Grade 1: normal,Grade 2: with mild systemic disease).The age of them should be within the range of 18-65 and the average age has to be 42.52 ± 9.6 years.Besides,their body mass index has to be within the range of 18-30 Kg / m2.The intravenous injection of 0.06 mg / kg midazolam and 1mg penehyclidine hydrochloride had to be made before anesthesia induction.Choose pressure control model to treat all patients and randomly divide 89 patients into four groups: P5 Kpa group,P10 Kpa group,P15 Kpa group and P20 Kpa group according to the different positive pressure ventilation values.Considering the possible impact of body mass index on the study,89 patients were randomly divided into normal group(BMI 18-25),overweight group(BMI 25-28)and obese group(BMI 28-32)to make weight impact assessment.Patients with supine position,the probe placed in the abdominal xiphoid sagittal longitudinal,showing the long axis of the abdominal aorta and the left lobe of the liver.The between the left lobe of the liver and the abdominal aorta can show the antrum has the oval cystic structure.We found the clearest section to measure the upper and lower diameter(D1)and the anteroposterior diameter(D2)through a vertical angle of D1,which were the gastric antral data before positive pressure ventilation.Later,anesthesiologists randomly gave airway pressure for positive pressure ventilation.The antrum area were measured after 180 s and got the gastric antral data.The antral area = ? * D1 * D2/4 was used to calculate the area of gastric antral area and compared the difference of the antral areas before and after ventilation with different positive pressure ventilation values.P <0.05 was chose to be statistically significant.Results:1 After the positive pressure ventilation,swimming gas with strong echo can be seen in the gastric antrum of the majority of patients.Tracking the gas,we could see the gas direction.Accurately measure the gastric antrum after 180 s.For a small number of patients,their gastric antrums were not clear enough to be measured because of the gas interference after the ventilation.Among 89 patients,69 patients' two-dimensional images were clear and their gastric antrum conditions could be accurately measured before and after the ventilation.The total display rate was 77.5%.The display rate of P5 group was 87.5%(21/24).The display rate of P10 group was 66.7%(14/21).The display rate of P15 was 80.0%(16/20).The display rate of P20 group was 75.0%(18/24).The comparison of the rate shows that there was no significant difference among the display rate in case of different positive pressure values.We used the data of 69 patients to make further analysis.P values of normality and variance homogeneity of the data were all above 0.05 in case of different positive pressure ventilation values,complying with normal distribution and variance.We used Multiple sample mean variance analysis: F = number outside the group / number inside the group = 1.060.We compared different positive ventilation pressure values in pairs and all P values were greater than 0.05,which suggested that there were no significant differences between the gastric antrum areas before and after the ventilation with the changes of the pressure value.2 In terms of body mass index,there were 55 of 89 patients in the normal group and the display rate of them was 74.5%.There are 14 patients in the overweight group and the display rate was 85.7%.There are 20 patients in obese group and the display rate was 80%.From the statistics,we obtained that P> 0.05,suggesting that body mass index from 18 Kg/m2 to 30Kg/m2 had no significant effect on the display rate.Conclusion: The real-time monitoring of gastric antrum using twodimensional ultrasound reflected that gastric air intake could happen during the anesthesia induction period,but the retention rate was very small.There was no significant difference in the amount of air intake before and after gastric ventilation.When body mass index was from 18 Kg/m2 to 30Kg/m2,the antrum had no significant effect on display rate,either.However,during the monitoring period,the antrum of a small number of patients could not be showed clearly because of the gastric gas interference.But there was no significant difference of their display rate in case of different positive pressure ventilation value and nearly the antrum of 80 percent of patients could be shown clearly and measured,which indicated using ultrasound to real-timely monitoring the variation of gastric antrum area could measure to the amount of gastric air intake to a certain degree.