Effect Of High Positive End-expiratory Pressure On Lung,ONSD And CBF In Patients Undergoing Laparoscopic Radical Rectal Cancer Surgery

Background and ObjectiveColorectal cancer is one of the most common malignancies,with both morbidity and mortality ranking among the top three in the world.In recent years,with the rapid development of laparoscopic technology,it has been widely used in radical rectal cancer surgery.However,in order to expose the surgical field better during low radical rectal cancer surgery,a long time of CO2 pneumoperitoneum and trendelenburg position are needed.This special condition not only causes an increase in intracranial pressure(ICP),but also has adverse effects on lung,resulting in increased airway pressure,atelectasis and postoperative pulmonary complications(PCCs).Several studies have shown that the use of higher levels of positive end expiratory pressure(PEEP)in laparoscopic surgery can effectively improve ventilation and reduce the incidence of atelectasis.However,the impact of PEEP on the cerebral is still unclear.Theoretically,the use of higher levels of PEEP will cause an increase in intrathoracic pressure,which would prevent venous return and induce a decrease in cardiac output.It will bring adverse effects to the brain,including increased ICP and decreased cerebral perfusion.Therefore,this study intends to evaluate the efficacy and safety of higher levels of PEEP in patients with laparoscopic rectal cancer by combining pulmonary function monitoring and craniocerebral ultrasound.Materials and MethodsSixty-nine patients who underwent laparoscopic radical rectal cancer surgery for rectal cancer were selected,aged 51 to 80 years,BMI 18 to 25 kg/m2,ASA Ⅰ or Ⅱ.Patients were randomly divided into 3 groups:0 cmH2O PEEP group(group P0),6 cmH2O PEEP group(group P6),and 12 cmH2O PEEP group(group P12).All three groups were routinely intubated under general anesthesia.Ultrasound was used to measure ONSD and MCA,at 15 minutes(T0)after induction of anesthesia,1 h(T1),2 h(T2)after PP and TP position,and 10 min(T3)after recovery from supine.Record HR,MAP,T,PETCO2,PaCO2,PaO2,hemoglobin(Hb)concentration,peak airway pressure(Ppeak),airway platform pressure(Pplat),driving pressure,lung dynamic compliance,MCA blood Flow parameter indicators,ONSD and rSO2.Postoperative pulmonary complications,acute stroke,and postoperative delirium(POD)were recorded on the 7th day after surgery.Data analysis was performed using SPSS 22.0 statistical software.Normal distribution measurement data are expressed as mean ±standard deviation(x ± s),single-variance analysis of variance is used for comparison between multiple groups,and repeated measurement design variance analysis is used for intra-group and inter-group comparison of repeated measurement data;chi-square test is used for comparison of count data.P<0.05 was considered statistically significant.Result1.General conditions.There was no significant difference in age,sex,weight,pneumoperitoneum time,anesthesia time,fluid intake,fluid output(urine volume±bleeding volume)among the three groups(P>0.05).2.General monitoring index.Comparison within group:Compared with T0,PETCO2 of the three groups of patients increased significantly at T1-3(P<0.05).Comparison between groups:There were no significant differences in MAP,HR,T and PETCO2 between three groups at different time points(P>0.05).3.Blood gas analysis index.Comparison within the group:Compared with T0,PaCO2 and of the three groups were significantly increased at T1-3,and PaO2 of P12 group was significantly increased at T1-3(P<0.05);three groups patients’ Hb decreased over time(P<0.05).Comparison between groups:PaO2,PaCO2 and Hb were not statistically different between the three groups at different time points(P>0.05).4.Pulmonary mechanical indicators.Comparison within the group:compared with T0,Ppeak and Pplat of the three groups were significantly increased at T1-3(P<0.05);the driving pressure of the P0 group was significantly increased at T1-3,lung dynamic compliance was significantly reduced(P<0.05),driving pressure in the P6 group increased significantly at T1-2,lung dynamic compliance decreased significantly at T1-2(P<0.05),and lung dynamic compliance in the P12 group was significantly decreased at T1-2 and increased significantly at T3(P<0.05).Ppeak,Pplat,and driving pressure of T3 in the three groups were significantly lower than T1-2,and lung dynamic compliance was significantly higher than T1-2(P<0.05).Comparison between groups:At T0,there was no significant difference in Ppeak,Pplat,driving pressure,and lung dynamic compliance among the three groups(P>0.05).At T1-3,the driving pressure of the P0 group was significantly higher than that of the P6 and P12 groups,and the lung dynamic compliance was significantly lower than that of the P6 and P12 groups(P<0.05);the Ppeak and Pplat of the P12 group were significantly higher than those of the group P0 and group P6(P<0.05).5.Craniocerebral indicators:comparison within the group:compared with T0,the three groups of patients had significantly increased ONSD,TAP,PI,RI,and rSO2 at T1-3(P<0.05);PI and RI were significantly lower than T1-2(P<0.05).Comparison between groups:At T1-2,the ONSD in the P12 group was significantly higher than that in the P0 and P6 groups(P<0.05),and there were no significant differences in rSO2,TAP,PI,and RI between the three groups at other time points(P>0.05).6.Postoperative complications:The incidence of postoperative pulmonary complications in the P6 and P12 groups was significantly lower than that in the P0 group(P<0.05),and there was no statistical difference between the P6 and P12 groups(P>0.05).There was no POD and other central nervous system complications occurred in all three groups.Conclusion1.During laparoscopic radical resection of rectal cancer,lung dynamic compliance decreases during PP and TP,airway pressure increases,ICP increases,cerebral perfusion and cerebral oxygen saturation increase;2.Both 6 cmH2O PEEP and 12 cmH2O PEEP could improve lung dynamic compliance during PP and TP,reduce driving pressure and the occurrence of PPCs without significant effects on cerebral perfusion and cerebral oxygen saturation;3.Compared with the normal level of 6 cmH2O PEEP,the high level of 12 cmH2O PEEP could increase PaO2,but it cannot reduce the occurrence of PPCs,and it will lead to higher ICP.