Electrical Impedance Tomography-guided PEEP Application In Patients Undergoing Gynecological Laparoscopic Surgery

Background:Electrical impedance tomography(EIT)is an emerging area of technology to monitor the current flow from the thorax and obtain the thoracic impedance,it has been used to lung impedance tomography,respiratory movement and Lung-protective Ventilation(LPV).Gynecological laparoscopic surgery is different from general surgery for the trendelenburg position and CO2 pneumoperitoneum which restrict the pulmonary ventilation,increase the risk of lung injury and postoperative pulmonary complications(PPCs).In this study we use EIT to provide a best PEEP during the gynecological laparoscopic surgery to find out whether it could decrease the risk of lung collapse and PPCs in order to provide theoretical basis and support for lung-protective ventilation in gynecological laparoscopic surgeries.Methods: We collected the clinical data of 24 patients aged between 18-65 who underwent the gynecological laparoscopic surgery from Ruijin Hospital.Patients were randomized into 2 groups(PEEP group and control group,12 patients each group).During the surgery,PEEP was used in PEEP groups,and control didn’t use PEEP.EIT was used(Pulmo Vista 500,Draegerwerk AG & Co.KGa A)to monitor ventilation distribution.After induction PEEP was titrated and increased 2cm H2 O per 5 minutes from 6 cm H2 O to 14 cm H2 O.When ROI3+ROI4(region of interest)reached the maximum,regard this PEEP value as “ideal PEEP” and keep it until the operation end.The EIT image,respiratory mechanics,oxygenation index(OI)and hemodynamic variables were recorded after the induction of anesthesia,PEEP titration,trendelenburg position,every 30 mins to the operation end.Recorded the hospitalization days and the postoperative pulmonary complications at the same time.Statistical analysis was performed using SPSS ver22.0 to analysis and compare the pulmonary ventilation.Results: 2 of 24 patients were eliminated because of the electrodes were placed below the diaphragm,the rest 22 patients were underwent gynecological laparoscopic surgery successfully.There were no significant difference existed among age,height,weight,surgery and anesthesia time,ASA class,intake of water,urination,hospitalization days and PPCs between two groups(P>0.05).For control group,EIT data didn’t change significantly after surgery(P=0.517),but for PEEP group,during PEEP titration ROI3+ROI4 increased significantly(P<0.001),the same outcome came out after surgery(P<0.001).Besides,EIT image and OI were different significantly between two groups(P=0.014 & P=0.022).Conclusion: EIT is a real time,radiation-free and non-invasive modality to monitor the respiratory mechanics during surgery.EIT can be used to titration PEEP to provide better oxygenation for patients to prevent the shift of ventilation and might get rid of PPCs.