Effect Of Equal Ratio Ventilation Combined With Individualized PEEP On Lung Function During Robotic-assisted Laparoscopic Radical Resection Of Cervical Cancer

Objective:To investigate the effect of ventilation mode of equal ratio ventilation（ERV）combined with individualized positive end expiratory pressure（PEEP）on lung function of patients undergoing robot-assisted laparoscopic radical hysterectomy for cervical cancer.Methods:Sixty-three patients undergoing robot-assisted laparoscopic radical hysterectomy for cervical cancer,ASA I-III,were randomly assigned into three groups:routine group（Group C）,individualized PEEP group（Group P）and ERV combined with individualized PEEP group（Group EP）,each group enrolled 21 patients.Respiratory parameters were set after induction of general anesthesia:tidal volume 8 ml/kg（ideal weight）,respiratory rate 12 beats/min,inhalation oxygen concentration 60%,inspiratory to expiratory ratios 1:2.After CO₂pneumoperitoneum combined with Trendelenburg position was established,the individualized PEEP was titrated with dynamic compliance of lung（Cdyn）in Group P and Group EP,while Group EP was adjusted I:E to 1:1,Group P and Group C were not adjusted.Mean arterial pressure（MAP）and heart rate（HR）were recorded before anesthesia induction（T₀）,after intubation（T₁）,10 min（T₂）,30 min（T₃）,60 min（T₄）,120 min（T₅）,180 min（T₆）,10 min after pneumoperitoneum（T₇）and 10 min after extubation（T₈）.Record platform pressure（Pplat）,peak pressure（Ppeak）,driving pressure（DP）,Cdyn and partial pressure of end-tidal carbon dioxide(P_ETCO₂)of T₁,T₂,T₃,T₄,T₅,T₆,T₇.Record the blood gas indexes of T₁,T₃,T₅,T₆,T₇(Pa O₂,Pa CO_2,PH,THbc,Hct,Lac,Glu).Oxygenation Index（OI）,partial pressure of alveolar oxygen（PAO₂）,alveolar-arterial oxygen pressure difference（A-a DO₂）and respiratory index（RI）were calculated.The amount of blood loss,fluid replacement,urine output and the dosage of vasoactive drugs were recorded.The atelectasis of T₀and T₈was evaluated by pulmonary ultrasound,and the arterial blood samples at T₀and T₈were collected to measure the serum levels of human clara cell protein（CC16）,malondialdehyde（MDA）,superoxide dismutase（SOD）and glutathione peroxidase（GSH-PX）by biochemical and ELISA methods.Results:1.General conditions There were no significant differences in age,height,body mass index,tidal volume,ASA classification,intraoperative infusion volume,blood loss,urine volume,anesthesia time,operation time and extubation time among the three groups（P>0.05）.2.Hemodynamic There was no significant difference in MAP and HR among the three groups at each time point（P>0.05）.Compared with T₀,MAP of the three groups decreased at T₁.Compared with T1,MAP of the three groups increased at T₂,and the difference was statistically significant（P<0.05）.Compared with T₂,the MAP of patients in Group P decreased from T₃to T₆,and the MAP of patients in Group EP decreased at T₆,and the difference was statistically significant（P<0.05）.3.Lung functionLung ultrasound evaluation There was no significant difference in preoperative lung ultrasound evaluation among the three groups（P>0.05）.The incidence of atelectasis in the three groups was different after extubation,and the difference was statistically significant（P<0.05）.Compared with Group C,the incidence of atelectasis in Group EP decreased after extubation,and the difference was statistically significant（P<0.05）.The incidence of atelectasis in Group P decreased after extubation,and the difference was not statistically significant（P>0.05）.Compared with Group P,the incidence of atelectasis in Group EP decreased after extubation,and the difference was not statistically significant（P>0.05）.There were significant differences in postoperative lung ultrasound scores among the three groups（P<0.05）.Compared with Group C,the postoperative lung ultrasound score in Group EP was lower,and the difference was statistically significant（P<0.05）.The postoperative lung ultrasound score in Group P was lower,and the difference was not statistically significant（P>0.05）.Compared with Group P,the postoperative lung ultrasound score in Group EP was lower,and the difference was not statistically significant（P>0.05）.Breathing mechanics There was no significant difference in Pplat and P_ETCO₂among the three groups at each time point（P>0.05）.Compared with Group C,there were significant differences in Ppeak at T₅,T₆,and T₇,and significant differences in DP and Cdyn at T₃to T₆in Group EP（P<0.05）.There were significant differences in DP and Cdyn at T₅and T₆in group P（P<0.05）.Compared with T₁,Pplat,Ppeak and DP increased and Cdyn decreased from T₂to T₆in the three groups.P_ETCO₂increased from T₄to T₇.In Group C,Pplat,Ppeak,DP increased and Cdyn decreased at T₇.In Group P,Ppeak and DP increased and Cdyn decreased at T₇,and the differences were statistically significant（P<0.05）.In Group C,Pplat at T₆was higher than that at T₂,T₃,T₄and T₅,and Ppeak at T₆was higher than that at T₃and T₄,and the differences were statistically significant（P<0.05）.There was significant difference between Group EP and Group P at T₃（P<0.05）.Compared with T₂,Ppeak and DP were significantly decreased and Cdyn was increased at T₃,T₄and T₅in Group EP,and DP was decreased at T₃in Group P（P<0.05）.Arterial blood gas analysis Compared with Group C and Group P,Group EP had higher Pa O₂and OI and lower A-a DO₂and RI at T₃,T₅and T₆,but the differences were not statistically significant.There was no significant difference in Pa CO₂among the three groups（P>0.05）.Compared with T₁,PAO₂and OI in Group EP increased at T₃and T₅,PAO₂decreased at T₅,T₆and T₇,A-a DO₂and RI decreased at T₃,T₅and T₆,and the differences were statistically significant.A-a DO₂and RI in Group C decreased at T₅and T₇,and the differences were statistically significant.In Group P,Pa O₂and OI increased at T₅,while A-a DO₂and RI decreased at T₅and T₆compared with T₁and T₃（P<0.05）.The Pa CO₂of the three groups increased from T₅to T₇,and the Pa CO₂of Group EP increased at T₃compared with T₁,and the difference was statistically significant（P<0.05）.Compared with T₃,PAO₂in Group C and Group P decreased from T₅to T₇,and the difference was statistically significant（P<0.05）.Pa CO₂in Group C and Group EP increased from T₅to T₇,and the difference was statistically significant（P<0.05）.4.Serological indicator There was no significant difference in CC16,MDA,SOD and GSH-PX among the three groups before and after operation（P>0.05）.In Group EP,CC16 and MDA decreased,while SOD and GSH-PX increased,but the difference was not statistically significant（P>0.05）.5.Postoperative complication No serious complications occurred in the three groups,and no adverse reactions such as bradycardia,hypotension,nausea and vomiting,and respiratory depression occurred during the perioperative period.Conclusion:The application of isometric ventilation combined with individualized PEEP in robotic-assisted laparoscopic radical resection of cervical cancer has stable hemodynamics,which can significantly reduce Ppeak and DP under CO₂pneumoperitoneum and Trendelenburg position,increase Cdyn,and reduce the incidence of atelectasis after extubation.Equal Ratio Ventilation combined with individualized PEEP maintains lower airway pressure levels faster and longer,achieving pulmonary protection than individualized PEEP.