Application Of PCV-VG Combined With Low PEEP In Obese Patients Undergoing Gynecological Laparoscopic Surgery In Trendelenburg Position

Objective:This study aimed to explore the safety and effectiveness of PCV-VG combined with low PEEP in obese patients undergoing gynecological laparoscopic surgery in the Trendelenburg position.To provide new methods and ideas for reducing the potential lung injury in obese patients.Methods:A total of 90 obese patients who were scheduled to undergo gynecological laparoscopic surgery under general anesthesia combined with transversalis fascia nerve block in our hospital from February 2022 to February 2023 were selected.This study is a prospective single-blind randomized controlled study.The patients were randomly divided into three groups A,B,and C by using the random number table method,that is,group A adopted PCV-VG combined with low PEEP（5 cm H₂O）ventilation mode,group B adopted PCV-VG ventilation mode（PEEP0 cm H₂O）,and group C adopted PCV-VG ventilation mode（PEEP 0 cm H₂O）.VCV ventilation mode（PEEP 0 cm H₂O）.The patients inthe group were routinely fasted for 6 hours and fasted for 8 hours before operation,and all patients did not use preoperative medication.Intravenous access was opened after entering the operating room.Routine monitoring of electrocardiogram（ECG）,blood pressure（BP）,heart rate（HR）,blood oxygen saturation（Sp O₂）.Radial artery puncture and catheterization were performed under local anesthesia for continuous monitoring of invasive arterial blood pressure during the operation.Anesthesia induction was started after tripartite verification by the surgeon,anesthesiologist,and itinerant nurse.After the patient reached the indication for intubation,a suitable endotracheal tube was placed through the mouth under a video laryngoscope,fixed,and then connected to an anesthesia machine to control breathing.The tidal volume is 7 m L/kg（standard body weight）,the respiratory rate is 12-20 times/min,the respiratory ratio is adjusted to 1:2,the inhaled oxygen concentration（Fi O₂）is 60%,and the flow rate is 2L/min.Intravenous inhalation compound anesthesia was used to maintain the depth of anesthesia,and bilateral transversalis fascia nerve block was performed under the guidance of ultrasound（0.33%ropivacaine 20 ml on each side）.Tidal volume and intraoperative drug dosage are calculated using standard body weight.Narcotrend is used to monitor the depth of anesthesia,maintain NT value of 45-55,monitor end-tidal carbon dioxide concentration,and maintain PETCO₂35-45mm Hg（1mm Hg=0.133KPa）by adjusting the respiratory rate.The fluctuation range of arterial pressure（MAP）does not exceed 20%of the basic value,and the pneumoperitoneum pressure is maintained at less than 13 mm Hg.After the operation is completed,send it to the anesthesia recovery room,wait for thepatient toregain consciousness,recover cough reflex and swallowing reflex,remove the tracheal tube when the spontaneous breathing tidal volume is greater than 6 m L/kg,the respiratory rate is greater than 10 times/min,and the PETCO₂is less than 45mm Hg.Administeroxygen andmonitor routinely.Main outcome measures:Mechanical ventilation related parameters（PEAK,Plat,Cdyn）at T1-T6 time point during operationSecondary observation indicators:（1）Patient’s age,BMI,type of operation,duration of operation,blood loss,volume of fluid replacement,urine output,etc.;（2）5 minutes after tracheal intubation（T₁）,60 minutes after operation（T₄）,postoperative PaO2,P（A-a DO₂）,OI,RI after the patient was awake and extubated the tracheal tube and inhaled 2 L/min O₂through thenose for 5 min（T₇）;（3）The occurrenceof pulmonary complications within 3 days after operation.Results:1.There was no significant difference in age,BMI,operation duration,intraoperative blood loss,fluid replacement volume,urine output,and operation type among the three groups（P>0.05）.2.Comparison of P_PEAKat different time points among the three groups of patients:there was no statistically significant difference between groups A and B at each time point（P>0.05）,and the P_PEAKof group A and group C at each time point was lower than that of group C,and the difference was statistically significant Significance（P<0.05）,the P_PEAKof group B was lower than that of group C in groups B and C at each time point,and the difference was statistically significant（P<0.05）.3.Comparison of Plat at different time points in the three groups of patients:there was no significant difference between groups A and B at each time point（P>0.05）,and the Plat in group Aand group C at each time point was lower than that in group C,and the difference was statistically significant.Statistically significant（P<0.05）,Plat in group B was lower than that in group C at each time point in groups B and C,and the difference was statistically significant（P<0.05）.4.Comparison of Cdyn at different time points in the three groups:Group A,B,and C had statistically significant differences at each time point（P<0.05）,and Cdyn in group A>Cdyn in group B>Cdyn in group C.Comparison of PaO₂at different time points in the three groups:There was no difference in PaO₂at T₁,T₄,and T₇time points ingroups A,B,and C（P>0.05）.5.Comparison of PaO₂at different time points in the three groups:There was no difference in PaO₂between groups B and C at T₁,T₄,and T₇time points（P>0.05）.The average PaO₂values of group Aat T₁,T₄,and T₇were slightly higher than those of groups B and C,but thedifference was not statistically significant（P>0.05）.6.Comparison of P（A-a DO₂）at different time points in three groups of patients:Group A,B,and C at T₁,T₄,and T₇time points compared with group A P（A-a DO₂）<group B P（A-a DO₂）<CGroup P（A-a DO₂）,but thedifference was not statistically significant（P>0.05）.7.Comparison of OI in three groups at different time points:at T₁and T₄,OI in group A>OI in group C>OI in group B,but the difference was not statistically significant（P>0.05）.There was no significant difference in OI among groups A,B,and C at T₇time point（P>0.05）.8.Comparison of RI at different time points of the three groups of patients（T₁,T₄,T₇）:the RI of group A at T₁,T₄,and T₇was lower than that of groups B and C,but the difference was not statistically significant（P>0.05）.9.Adverse reactions:1 case of postoperative pulmonary complications in group A,with an incidence rate of 3.5%;3 cases of postoperative pulmonary complications in group B,with an incidence rate of 10.0%;4 cases of postoperative pulmonary complications in group C,the incidence rate was 13.3%.There was no statistically significant difference in adverse reactions among thethree groups（P>0.05）.Conclusion:1.PCV-VG combined with low PEEP（5cm H₂O）ventilation mode can be safely and effectively applied to obese patients undergoing gynecological laparoscopic surgery in the Trendelenburg position.2.The PCV-VG ventilation mode can effectively reduce the peak airway pressure and plateau airway pressure in obese patients,and at the same time improve the dynamic compliance of thelung（Cdyn）,which has a certain lung protection effect.3.PCV-VG combined with low PEEP（5cm H2O）ventilation mode has significant advantages in improving lung dynamic compliance（Cdyn）compared with PCV-VG ventilation mode alone.