Postoperative Diaphragmatic Functional Changes Under VCV And PCV In Elderly Patients Undergoing Laparoscopic Surgery In The Trendelenburg Position And Correlation With Perioperative Atelectasis

Objective:To explore the effects of volume-controlled ventilation(VCV)and pressure-controlled ventilation(PCV)on postoperative diaphragmatic function under lung-protective ventilation strategy in elderly patients undergoing laparoscopic surgery in the Trendelenburg position,and to investigate the correlation between postoperative diaphragmatic function and perioperative pulmonary atelectasis.Methods:The study included 70 elderly patients,ASA class II～III,aged ≥60 years,sex unlimited,who were undergoing laparoscopic surgery in the Trendelenburg position in Bethune First Hospital of Jilin University from September 2022 to December 2022.The patients were randomly assigned to VCV group or PCV group in the ratio of 1:1 by random grouping software SPSS,with 35 cases in each group.Based on the lung protective ventilation strategy,VCV and PCV were used in the two groups to maintain the tidal volume(Vt)at 6～8 m L/kg.Diaphragmatic excursion(DE)and diaphragmatic thickness fraction(DTF)were observed and recorded by ultrasound before anesthesia(T0),15 min after extubation(T1),24 h after surgery(T2)and 48 h after surgery(T3)during quiet breathing(QB)and deep breathing(DB).Patients were also observed for pulmonary atelectasis and the lung ultrasound score(LUS)was recorded.The incidence of pulmonary complications within 7 days after operation was analyzed.Results:Intra-group comparison: The quiet breathing diaphragmatic excursion(DE-QB),deep breathing diaphragmatic excursion(DE-DB)and deep breathing diaphragm thickness fraction(DTF-DB)of the two groups were lower than T0 at T1,T2 and T3(P<0.05),and were significantly higher at T3 compared with T1(P<0.05).The quiet breathing diaphragmatic thickness fraction(DTF-QB)was only lower at T1 than at T0(P<0.05),with no significant differences between T2,T3 and T0,T1(P>0.05).Compared with T0,the LUS of the two groups was significantly increased at T1 and T2(P<0.05).And then decreased at T2 and T3 compared with T1(P<0.05).Comparison between groups: The DE-QB and DE-DB of patients in the PCV group were higher than those in the VCV group at T1 and T2(P<0.05),and there was no significant difference between the two groups at T3(P>0.05).The DTF-QB was not significantly different between the two groups at each time point(P>0.05).The DTF-DB was higher in the PCV group than in the VCV group at T1,T2,and T3(P<0.05).The LUS was significantly lower in the PCV group than in the VCV group at T1(P<0.05),and there was no statistically significant difference between the two groups at T2 and T3(P>0.05).There was no significant difference in the incidence of pulmonary complications between the two groups within 7 days after operation(P>0.05).Correlation: At the moment of T1,the DE-QB(r =-0.532,P<0.01),DE-DB(r =-0.458,P<0.01),DTF-QB(r =-0.309,P<0.01)and DTF-DB(r =-0.557,P<0.01)were correlated with the LUS in both groups.Conclusion:In elderly patients undergoing laparoscopic surgery in the Trendelenburg position,a decrease in postoperative diaphragmatic function is seen.Compared with VCV,the application of PCV based on lung-protective ventilation strategy has less impact on diaphragmatic function and can reduce the severity of perioperative pulmonary atelectasis,but has no significant effect on the incidence of pulmonary complications in patients within7 days after operation.In addition,there is a correlation between postoperative diaphragmatic function and perioperative pulmonary atelectasis.