Effects Of Driving Pressure-guided Individualized PEEP On Intraoperative Pulmonary Function And PPCs Of Patients Undergoing Laparotomy

ObjectiveCombined with little tidal volume and recruitment maneuvers,to compare the effects of driving pressure-guided individualized PEEP and constant 5cmH₂O PEEP on intraoperative pulmonary function and PPCs of patients undergoing laparotomy.Explore whether driving pressure-guided individualized PEEP could improve intraoperative pulmonary function and reduce the occurrence of PPCs.MethodsForty patients,aged 18-80 years old,with ASA II^III,underwent elective laparotomy under general anesthesia,with an estimated operation time>120min.Patients were randomly divided into two groups according to numerical randomization?n=20?:group C?PEEP=5cmH₂O?and group P?driving pressure-guided individualized PEEP?.Both groups adopted volume-controlled ventilation mode?VCV?,setting the tidal volume?VT?to an ideal body weight of 6ml/kg,the inspiratory and expiration ratio to 1:2,and the FIO₂ to 0.4.Adjusting the RR according to the end-tidal carbon dioxide partial pressure?PetCO₂?,maintaining PetCO₂ between 35-45mmHg.After intubation,patients in both groups underwent recruitment maneuvers by manipulation,the ventilator was adjusted to manual ventilation mode,and the airway pressure limiting valve?APL valve?was set to40cmH₂O The recruitment maneuvers was made by squeezing the air bag,which was repeated for 3 times and lasted for 5s each time.The PEEP value of group C was set as 5cmH₂O after recruitment maneuvers,and the PEEP value of group P was determined by driving pressure-guided titration PEEP method.Recorded separately at the following time points:after PEEP set 10min?T1?,operation 60min?T2?,operation120min?T3?,5min before extubation?T4?:invasive arterial blood pressure,heart rate,pulse oxygen saturation,and end-tidal carbon dioxide partial pressure,airway peak pressure,airway plateau pressure;arterial blood was extracted for blood gas analysis,and oxygen partial pressure and arterial carbon dioxide partial pressure of arterial blood were recorded.PaO₂/FIO₂,dead cavity rate,and driving pressure were calculated,and the titrated PEEP values of group P were recorded.After the operation,the operation time,intraoperative infusion of fluid and the use of vasoactive drugs were recorded,and the occurrence of PPCs was recorded at 5 days after surgery.ResultsIntra-group comparison:at the T4 time point,the driving pressure and dead cavity rate of patients in both groups were lower than that at the T3 time point?P<0.05?.Comparison between groups:compared with group C,the driving pressure of patients in group P decreased at time T2-T4,PaO2/FIO2 increased at time T2-T4?P<0.05?,and the incidence of PPCs in group P decreased.There was no significant difference in the rate of dead cavity rate between the two groups?P>0.05?.There was no significant fluctuation in hemodynamics during the operation,and no significant difference in the use of vasoactive drugs?P>0.05?.The P group drive pressure-guided individualized PEEP has a median of 7cmH₂O.ConclusionFor patients undergoing laparotomy,the median value of individual PEEP guided by driving pressure was 7cmH2O,higher than the consensus recommendation of exp erts of 5cmH2O.Recruitment maneuvers combined with PEEP can reduce alveolar de ad space,improve ventilation efficiency and reduce driving pressure.Driving pressure-guided individualized PEEP can better improve PaO2/FIO2,improve intraoperative p ulmonary ventilation,reduce the occurrence of PPCs,and have less impact on the circ ulation system.Therefore,it can be used for clinical guidance to set PEEP.