Effect Of Small Tidal Volume Combined With Lung Recruitment On Lung Air Volume In Patients Undergoing Retroperitoneal Laparoscopic Surgery

Objective:Using lung ultrasound techniques,To investigate the effect of small tidal volume combined with lung recruitment on the air content of the lungs in patients undergoing retroperitoneal laparoscopic surgery.Methods:Sixty patients underwent laparoscopic urologic surgery,including ASAI grade or grade Ⅱ,aged 18-65 years,and body mass index(BMI)18-30 kg/m2.The enrolled patients were divided into two groups according to the random number table method,30 cases in each group.The control group(group C)underwent volume control ventilation,50%air-oxygen mixed fresh gas flow 1.5L/min,tidal volume 8ml/kg(ideal weight)fixed setting,I:E=1:1.5,respiratory rate f=14-18 times/min,PEEP 0 cmH2O,no lung re-expansion during surgery;The ventilation mode of the re-expansion group(group R)was the same as that of group C.The lung re-expansion was performed every 30 min after tracheal intubation.The volume-controlled ventilation mode was changed to pressure-controlled ventilation mode when the lung was re-expanded,and the driving pressure was set to 20 cmH2O.PEEP gradually increased,increasing by 5 cmH2O every step,increasing to 20cmH2O,ie:PEEP increased from 0 to 15cmH2O,for every 5 cmH2O increase,maintaining 3 breaths,maintaining 10 breaths when PEEP increased to 20 cmH2O,then PEEP dropped to 0 cmH2O,the pressure-controlled ventilation mode was also changed to the original capacity control ventilation mode.The peak airway pressure(Ppeak),plateau pressure(Pplat),end-of-breath carbon dioxide(PetCO2)and dynamic lung compliance(Cdyn)were recorded 5 minutes after intubation(T2),5 minutes after lateral decubitus position(T3),5 minutes after pneumoperitoneum(T4),0.5 hours after pneumoperitoneum(T5),1 hour after pneumoperitoneum(T6),and 5 minutes after pneumoperitoneum finish(T7).Ultrasound examination of the chest region(divided into 12 regions)and scoring,observation time points included in the preparation of anesthesia(T1),0.5 hours after extubation(T8)and 24 hours after surgery(T9),recording the score of each region(LUS);Blood gas analysis of T1 and T8 was collected and arterial partial pressure of oxygen(PaO2),arterial partial pressure of carbon dioxide(PaCO2)and oxygenation index(OI)were recorded.Systolic blood pressure(SBP),diastolic blood pressure(DBP)and heart rate(HR)were recorded 1 minute before and 1 minute after re-expansion in group R,and the average value(sum divided by times)was obtained.Ppeak,Pplat and Cdyn were recorded before,5 minutes after,10 minutes after and 15 minutes after re-expansion in group R.The average value of the records(sum divided by the number of lung reexpansions)was taken.Results:Compared with T1,the LUS scores of T8 and T9 were increased in both groups,and the LUS scores of T9 and T8 were decreased(P<0.05).Compared with group C,LUS at T8 and T9 in group R.The scores were all decreased(P<0.05).Compared with group C,PaO2,OI in group R T8 increased significantly,while PaCO2 decreased(P<0.05);Compared with group C,group R had significantly increased Cdyn after of T7(P<0.05),PaCO2 decreased(P<0.05).Conclusion:1.After general anesthesia,the air content in the pulmonary ultrasound images of patients undergoing retroperitoneal laparoscopic urology surgery decreased to varying degrees,especially in the contralateral dorsal region,and lasted for more than one day after operation;2.Small tidal volume ventilation combined with pulmonary reexpansion during anesthesia can effectively improve the performance of pulmonary ultrasonography,reduce the accumulation of CO2 and increase oxygenation;3.The effect of this ventilation method on hemodynamics is slight and transient.