Effect Of Open Lung Strategy On Atelectasis Assessed By Lung Ultrasound In Patients Undergoing Gynecological Laparoscopic Surgery

Objectives:The use of lung ultrasound to assess whether the open lung strategy can reduce the incidence of perioperative atelectasis in gynecologic laparoscopic surgery in patients.Methods:The project applied randomized controlled trial(RCT),and selected 42 patients of gynecologic laparoscopic surgery in Affiliated Hospital of North Sichuan Medical College from may,2020 to October,2020.The patients ranged in age from 18 to 65.According to the random number table method,they were divided into open lung strategy group(E)and traditional protective mechanical ventilation group(C),with 21 cases in each group:group E with external PEEP of 6cmH2O and RMs,group C with external PEEP of 6cmH2O and no RMs.During general anesthesia,all the patients were given the same anesthesia method,the same ventilation mode was used,and recruitment manoeuvre was performed guided by lung ultrasound according to the design requirements.All the selected patients were ventilated using volume-controlled ventilation,tidal volume of 6-8 ml/kg of predicted body weight,the end-tidal CO2 partial pressure between 30 and 40mmHg by adjusting ventilatory frequency,and recruitment manoeuvre was performed guided by lung ultrasound according to the design requirements.The parameters of the ventilator were as follows:the oxygen flow was 2L/min and the ratio of inspiratory and expiratory was 1:2.Lung ultrasound examination was performed five times in each patient by using an abdominal convex array probe of 2-5MHz.Images were obtained at 5 predefined time points:arrival in the operating suite(time point T0),after tracheal intubation(time point T1),at end of surgery(time point T2),post-operation PACU(time point T3),after 1 day(time point T4).Parts of LUS observation:the chest was divided into 12 regions,with 6 sections in each hemithorax.Each side was divided into anterior,lateral and posterior zones using three longitudinal lines that include parasternal,anterior and posterior,which divided in upper and lower portions by two axial lines one above the diaphragm and another one at the nipples.At the end of the operation,the patient’s endotracheal tube was removed after the indication for extubation was reached,and the patient was sent to PACU for observation.Experimental observation index:PaO2,PaCO2,OI,SpO2,lung ultrasound scores,length of mechanical ventilation,length of surgery,intraoperative fluid flow,length of PACU time,NRS,postoperative pulmonary symptoms,length of stay.Results:(1)A total of 41 patients were enrolled in group C(21 cases)and group E(20 cases)in the trial.There were no statistically significant differences between the two groups in the following aspects:age,BMI,ASA grade,length of mechanical ventilation,length of surgery,fluid flow,NRS,length of PACU time,PaO2,SpO2,PaCO2,OI,postoperative pulmonary symptoms,and lung ultrasound score at T0(P>0.05).(2)No statistically significant difference was found between group C and group E in the incidence of atelectasis and LUS scores at T1,T2 and T4(P>0.05).(3)The incidence of pulmonary atelectasis and LUS scores in group E were significantly lower than those in group C at T3,and the difference was statistically significant(P<0.05).(4)The LUS scores of the anterior regions and the lateral regions were not significantly different at T2,T3 and T4(P>0.05),while the LUS scores of the posterior regions were higher than other parts(P<0.05).Perioperative atelectasis mainly occurred in the posterior regions of the lung.(5)LUS scores was a positive correlation between and age,body weight and BMI at T2,T3 and T4.Conclusions:Lung ultrasound observation showed that the open lung strategy can effectively reduce the incidence and severity of atelectasis in PACU,but its advantage disappears one day after the operation,and without significant influence on the incidence and severity of atelectasis in one day after the operation.