Effects Of Driving Pressure Guided Individualized Positive End-expiratory Pressure On Perioperative Pulmonary Function Of Patients With Traumatic Brain Injury

Objective:To investigate the effect of driving pressure-oriented individualized positive end-expiratory pressure（PEEP）ventilation strategy on perioperative pulmonary function in patients with traumatic brain injury（TBI）.Methods:Eighty-two patients with TBI who underwent cranial surgery under emergency general anesthesia,aged 18～65 years,ASA class Ⅱ-Ⅳ,were selected.Patients were randomized according to a random number table into a control group without PEEP（group A,n=28）,a PEEP group with 5 cmH2O（group B,n=27）,and an individualized PEEP group with driving pressure guidance（group C,n=27）.The fraction of Inspiration Oxygen（FiO2）1.0 was preoxygenated for 5min,and tracheal intubation was performed after rapid anesthesia induction according to the treatment process of preventing reflux aspiration.Volume controlled Ventilation（VCV）mode is adopted for mechanical ventilation.Tidal volume is 6ml/kg,respiratory rate is 13 times/min,suction ratio is 1:2,FiO2 0.5.After hemodynamic stability,corresponding ventilation strategies are adopted according to groups.Patients in group A were not given PEEP;Patients in group B received PEEP of 5cmH2O;Patients in group C were titrated with driving pressure positive end-expiratory pressure:PEEP was gradually increased from 2cm H2O to 10cm H2O,each PEEP level（2,3,4,5,6,7,8,9,10 cm H2O）was maintained for 10 breathing cycles,and driving pressure for the last cycle was recorded at each PEEP level.Then the optimal PEEP level is selected to produce the lowest driving pressure.Invasive arterial pressure measurement was performed before anesthesia induction in all patients,and records were recorded before anesthesia induction(T0,5min after endotracheal intubation（T1）,and immediately after PEEP titration in group C（T2,Mean arterial pressure（MAP）,PaO2 and PaCO2 in groups A and B at 10min ventilation）,60min after operation（T3）and end of operation（T4）;Lung ultrasound Score（LUS）and optic nerve Sheath diameter（ONSD）measurements of T0,T2 and T4 were recorded.Lung compliance（Cdyn）and driving pressure at T1,T2,T3 and T4 were recorded.Postoperative pulmonary complications（PPCs）were recorded in three groups within 7 days after surgery.Age,sex,body mass index（BMI）,operation time and other general preoperative information of all patients were recordedResults:A total of 82 patients undergoing emergency craniocerebral surgery were included in the study.In terms of respiratory parameters,the optimal PEEP in group C was 6.95±1.36cmH2O.At T2,T3 and T4,the driving pressure in group B and C was significantly lower than that in group A（P<0.05）,and the driving pressure in group C was significantly lower than that in group B（P<0.05）,there was no statistical difference among the three groups at the remaining time points;At T2,T3 and T4,Cdyn in group B and C was significantly higher than that in group A,and group C was significantly higher than that in group B（P<0.05）,and there was no statistical difference among the three groups at other time points.In terms of pulmonary ultrasound score and pulmonary oxygenation,the LUS score of group B and C was significantly lower than that of group A at T2 and T4（P<0.05）,and the LUS score of group C was significantly lower than that of group B（P<0.05）.At T2,T3 and T4,PaO2 in group B and C was significantly higher than that in group A（P<0.05）,and group C was significantly higher than group B（P<0.05）.In terms of safety,there was no statistically significant difference in mean arterial pressure at different time points from T0 to T4 among the three groups,and no statistically significant difference in ONSD at T0,T2 and T4 among the three groups.In terms of postoperative pulmonary complications,the main observed indicators were pneumonia within 7 days after surgery,re-intubation,postoperative oxygenation index（PaO2/FiO2）less than 100g,postoperative atelectasis,etc.Data showed that the incidence of postoperative pulmonary complications in group B and C was significantly lower than that in group A（P<0.05）,and group C was significantly lower than group B（P<0.05）.Conclusion:1.The optimal value of PEEP titration for TBI patients undergoing brain surgery guided by driving pressure was 6.95±1.36 cmH2O.2.Driven pressure-guided individualized PEEP lung protective ventilation strategy can significantly improve intraoperative lung compliance,improve oxygenation,reduce pulmonary super score,and reduce the incidence of pulmonary complications in TBI patients within 7 days after surgery.3.Driven pressure-oriented individualized PEEP ventilation strategy had no significant effect on the intraoperative MAP and ONSD of patients undergoing TBI surgery,indicating that it was a relatively safe and feasible ventilation strategy for lung protection.