Effects Of Different Levels Of PEEP On Perioperative Pulmonary Atelectasis By Lung Ultrasonography

Objectives:The aim of this study was to observe the effects of positive end-expiratory pressure?PEEP?on perioperative pulmonary atelectasis in patients undergoing laparoscopic cholecystectomy by lung ultrasonography,and to investigate the appropriate level of PEEP in laparoscopic cholecystectomy.Methods:120 patients scheduled to undergo laparoscopic cholecystectomy,were randomly divided into three groups?40 cases in each group?using a random number table:group I with no external PEEP,group II with external PEEP of 5 cm H₂O,group III with external PEEP of 8 cm H₂O.After the tracheal intubation,the volume control ventilation of the respiratory parameters was set as required.Lung ultrasonography was performed at 3predefined time points:1 day before surgery?T1?,30 minutes after extubation?T2?,20-30hours after surgery?T3?.Parts of LUS observation:the thorax was divided into 12quadrants:anterior,lateral,and posterior zones separated by the anterior and posterior axillary lines,which divided in upper and lower portions for the right and left lung.Intercostal spaces of each of these areas were scanned and a cine-loop of the most pathologic area of each quadrant was saved to digital format for offline analysis.LUS scores:0:clear A line and lung slide sign and 0-2 B lines;1:?3 B lines or 1 or multiple small subpleural consolidations separated by a normal pleural line;2:multiple coalescent B lines or multiple small subpleural consolidations separated by a thickened or irregular pleural line;3:consolidation or small subpleural consolidation of>1×2 cm in diameter.Results:?1?There was no significant difference in the mean LUS scores among the three groups at T1 time?p>0.05?.At time point T2 and T3 the mean scores of LUS of group?were higher than group???,and group?were higher than group?,the differences were statistically significant?p<0.05?;?2?The average of three groups of LUS total score points increased significantly at T2 time,but decreases at T3 time,the difference was statistically significant?p<0.05?.Three groups on the left and right rear lung and lung under the left and right rear area respectively showed a trend of the change,the difference was statistically significant?p<0.05?;?3?At time point T2 and T3,the difference between the left and right posterior upper lung area and the posterior lower lung area of the three groups was statistically significant?p<0.05?;?4?At time point T2 and T3 the SpO₂ of group???was higher than that of group?,at time point T3 the SpO₂ of group?was higher than that of group?,the difference was statistically significant?p<0.05?;?5?Ppeak?Pplat and Cdyn of group?were significantly higher than group?and group?,group?were significantly higher than group?,the differences were statistically significant?p<0.05?.Conclusions:According to the results of pulmonary ultrasound examination in this study,patients with laparoscopic cholecystectomy can occur to a certain degree of atelectasis,which can be sustained to more than one day after surgery,especially with significant change for the bilateral posterior back.In the course of artificial ventilation,the use of a certain level of PEEP can improve atelectasis on postoperative.In the scope of this study,8cm H₂O level has the best results,while increasing the dynamic compliance of the lung and improve oxygenation.