Effect Of Lung Protective Ventilation With Different PEEP Values On Respiratory Mechanics And Oxygenation In Elderly Patients Undergoing Laparoscopic Colorectal Surgery

ObjectiveTo compare the effects of two levels of PEEP lung protective ventilation on perioperative respiratory mechanics and oxygenation in elderly patients undergoing laparoscopic colorectal cancer surgery.MethodsA total of 60 cases of laparoscopic surgical anesthesia for colorectal cancer from December 2019to June 2020 were selected,including 30 males and 30 females.According to the principle of random allocation,20 patients were divided into conventional group（CMV group 0cm H₂O PEEP）,low PEEP group（PMV1 group 7cm H₂O PEEP）20 patients,and high PEEP group（PMV2 group 12cm H₂O PEEP）20 patients.All the three groups were treated with the same anesthesia method and the combination of anesthetics.CMV group was treated with traditional ventilation mode and returned to the ward after intraoperative extubation to PACU.PMV group was treated with lung protective ventilation strategy combined with PEEP of different sizes,and then returned to the ward after extubation to PACU.Record15 min after the three groups of patients with tracheal intubation（T₀）,30 min after pneumoperitoneum（T₁）,90 min after pneumoperitoneum（T₂）of each point in time airway peak pressure(P_peak),mean airway pressure(P_mean),platform(P_plat),driving pressure,the dynamic lung compliance（Cydn）,in T₀,T₁,T₂ and pulling the endotracheal tube after 20 min（T₃）take radial artery blood,arterial blood gas analysis,Pa O₂,Pa CO₂,Oxyxation index（OI）,respiratory index（RI）,alveolar oxygen partial pressure--arterial oxygen partial pressure difference[P（A-a）DO₂]were calculated according to Pa O₂,Pa CO₂ and Fi O₂,which were the main observation indexes.PH,mean arterial pressure（MAP）and heart rate（HR）were recorded as secondary outcomes.Results1.There was no statistical significance in the general conditions of the three groups,including gender,age,height,weight,BMI and smoking status（P>0.05）;2.In terms of airway pressure,there were no significant differences in P_peak and P_plat between PMV1group and control group at T₀,T₁ and T₂（P>0.05）,while P_mean in PMV1 group was significantly higher than that in control group at T₀ and T₁（P<0.05）.At T₀,T₁ and T₂,P_peak and P_mean in PMV2 group were significantly higher than those in control group and PMV1 group（P<0.05）.At T₀,P_plat in PMV2 group was significantly higher than that in control group and PMV1 group（P<0.05）.P_plat in PMV2 group was significantly higher than that in PMV1 group at T₂（P<0.05）.In terms of driving pressure,the driving pressure of PMV1 group and PMV2 group at each time point（T₀,T₁,T₂）was significantly lower than that of control group（P<0.05）,and the driving pressure of PMV2 group after pneumoperitoneum（T₁,T₂）was significantly lower than that of PMV1 group（P<0.05）;3.In terms of pulmonary dynamic compliance,after pneumoperitoneum（T₁,T₂）,the Cydn of PMV1and PMV2 groups was significantly higher than that of control group（P<0.05）.There was no significant difference between PMV1 group and PMV2 group（P>0.05）;4.On the effect of circulation,At T₀ and T₁,MAP in PMV2 group was significantly lower than that in control group and PMV1 group（P<0.05）.There was no statistical significance in HR between and within the three groups at T₀,T₁,T₂ and T₃（P>0.05）;5.In terms of oxygenation function,Pa O₂ in PMV1 group was significantly higher than that in control group at T₁,T₂ and T₃（P<0.05）.At T₃,Pa O₂ in PMV1 group was significantly higher than that in PMV2group（P<0.05）.At T₁,T₂ and T₃,the OI of PMV1 group was significantly higher than that of control group（P<0.05）.At T₂,the OI in PMV2 group was significantly higher than that in control group（P<0.05）.At T₃,the OI in PMV1 group was significantly higher than that in PMV2 group（P<0.05）.At T₂ and T₃,P（A-a）DO₂ in PMV1 group was significantly lower than that in control group（P<0.05）;At T₃,P（A-a）DO₂ in PMV1 group was significantly lower than that in PMV2 group（P<0.05）;6.There was no statistical significance in the incidence of intraoperative and postoperative pulmonary complications among the three groups（P>0.05）.Conclusions:1.In elderly patients undergoing laparoscopic colorectal cancer surgery,compared with the traditional ventilation mode,reasonable application of lung protective ventilation strategy combined with positive end-expiratory pressure can effectively improve intraoperative oxygenation and respiratory mechanical parameters;2.Compared with PEEP at 12cm H₂O level,PEEP at 7cm H₂O level has more advantages in the control of respiratory mechanics,hemodynamic stability and improvement of oxygenation function,so it is suitable for application in this surgery.