Effect Of Individualized Peep In Different Positions On Respiratory Parameters In Patients Undergoing Posterior Lumbar Surgery

Objective:To observe the effects of individualized PEEP on arterial oxygen partial pressure,oxygenation index and pulmonary compliance in patients undergoing posterior lumbar surgery in different postures,and to compare the incidence of postoperative pulmonary complications,in order to provide more clinical basis for the application of lung protective ventilation strategy in prone surgery.Methods:Sixty patients with lumbar spine surgery by posterior approach under general anesthesia were randomly divided into supine pressure group,prone pressure group and control group,with 20 cases in each group.Individualized PEEP was titrated under the guidance of pulmonary dynamic compliance.The best positive end expiratory pressure in supine position and the best positive end expiratory pressure in prone position were measured in supine position and prone position respectively.Pa O₂,Pa CO₂,OI were recorded before induction（T₀）,5min after optimal PEEP（T₁）,1h after optimal PEEP（T₂）,5min before completing operation（T₃）,30min after leaving the operating room（T₄）,72h after operation（T₅）;Pplat、Ppeak、Cdyn were recorded at T₁-T₃,HR and MAP were recorded at T0-T4,and the incidence of respiratory tract infection,such as pneumothorax,respiratory failure and pleural effusion after operation 72h also were recorded.Results:1.There was no significant difference in gender,age,weight,height,BMI,infusion volume,bleeding volume,urine volume and operation time among the three groups（P>0.05）.2.There was no significant difference in MAP and HR among the three groups at each time point（P>0.05）.3.Titrate the individualized PEEP value under the guidance of cdyn.The individualized PEEP value is 7.95±1.38cm H₂O in supine position and 11.35±1.50cm H₂O in prone position.4.Comparison of the values of Pplat,Ppeak and Cdyn in three groups at different time points.At each time point,the values of Pplat,Ppeak and Cdyn in group S and group P were higher than those in group C（P<0.05）,and the three indexes in group P were higher than those in group S（P<0.05）.There was no significant difference in the value of Pplat among the three groups（P>0.05）;At T₃time point,the Ppeak of S group and P group were lower than those at T₁,and the Cdyn value were higher than those at T₁（P<0.05）.5.Comparison of Pa O₂,Pa CO₂and OI values in three groups at different time points.At T₂,T₃and T₄,Pa O₂and OI of group S and group P were higher than those of group C（P<0.05）,but there was no significant difference between group S and group P（P>0.05）;There were no significant difference in Pa O₂and OI among the three groups at T₀,T₁and T₅（P>0.05）;There was no significant difference in Pa CO₂among the three groups at each time point（P>0.05）.At T₃time point,the Pa O₂and OI values of the three groups were higher than those at T₁time point（P<0.05）;At T₄time point,Pa O₂and OI of the three groups were higher than those at T₀time point（P<0.05）;At T₀and T₅time points,there were no significant difference in Pa O₂and OI among the three groups（P>0.05）.6.Comparison of postoperative pulmonary complications among the three groups.The incidence of pulmonary complications in group S and group P was lower than that in group C,but the difference was not statistically significant（P>0.05）.Conclusion:In posterior lumbar surgery,the individualized PEEP measured in prone position is higher than that measured in supine position,and the lung compliance of patients with individualized PEEP in prone position is higher than that of the other two groups.The intraoperative application of individualized PEEP can reduce the incidence of postoperative pulmonary complications compared with the control group,but the difference is not statistically significant.