The Lung-protective Effct Of PCV-VG Combined With Individualized PEEP On Patients Undergoing Laparoscopic Surgery In Trendelenburg Position

Objectives The study aimed to evaluate the effect of the lung effect of pressure-controlled ventilation-volume guaranteed mode（PCV-VG）combined with individual positive end-expiratory pressure（PEEP）during laparoscopic surgery in Trendelenburg position.Methods 120 patients aged 18-82 yr,with BMI<35 kg/m²,ASA（American Society of Anesthesiologists）I-III stages,who underwent laparoscopic surgery in Trendelenburg position under the general anesthesia of Hebei General Hospital during the period from September of 2020 to December of 2020 were randomly divided into 4 groups（n=30）using a list of random number table:group VF（volume control ventilation[VCV]mode plus fixed PEEP of 5cm H₂O）,group PF（PCV-VG plus fixed PEEP of 5cm H₂O）,group VI（VCV mode plus individual PEEP）,and group PI（PCV-VG plus individual PEEP）.During the procedure the PEEP titrations would be performed twice in group VI and group PI:after tracheal intubation and establishment of Trendelenburg position and pneumoperitoneum.PEEP,mean airway pressure（Pmean）,peak airway pressure（Ppeak）,dynamic compliance（Cdyn）were recorded at T₁（15 minutes after endotracheal intubation）,T₂（60 minutes after CO₂ pneumoperitoneum and Trendelenburg position were set）,and T₃（5 minutes after placement in the supine position at the end of anesthesia）.We calculated Pa O₂/Fi O₂,alveolar artery partial pressure of oxygen（A-a DO₂）,intrapulmonary shunt ratio（Qs/Qt）,and dead space fraction（V_D/V_T）at T₁,T₂ and T₃.The serum CC16 and IL-6concentrations were evaluated to investigate the lung-injury of the patients at T₁ and T₃.Record the patient’s complications within 72 hours after surgery,including:body temperature>38°C,cough,sputum,the number of white blood cells and neutrophils.Results 1 Patients enrolment and demographic and Intraoperative Characteristics.The trial enrolled 140 patients planning to undergo Trendelenburg laparoscopic surgery,finally,120 people completed the test（Figure 1）.There were no significant difference among patients of the four groups in gender,age,height,BMI,PBW,anesthesia time,operation time,pneumoperitoneum time,operation type,intraoperative fluid volume and intraoperative application of vasoactive drugs（P>0.05）（Table 1 and Table 2）.2Respiratory Mechanics.Compared with groups VF and PF（with a fixed PEEP of5cm H₂O）,the level of PEEP was increased in the group PI and group VI at T₁ and T₂,and there was no significant difference in group VI and group PI（P>0.05）.At T₂,the Pmean was decreased in the group PF and group VF than in the group VI and group PI（P<0.05）.And the Pmean was decreased in the group PI than in the group VF and PF at T₃（P<0.05）.Ppeak was decreased in the group PI compared with the group VI,group VF,and group PF at T₂（P<0.05）.At T₃,the Ppeak was increased in the group VI than in the group PF and group VF（P<0.05）.And the Ppeak was decreased in the group PI than in the group VI at T₃（P<0.05）.The Cdyn was increased in the PI group than in the group PF and group VF throughout the study period（P<0.05）.Cdyn was increased in the group PI compared with group VI at T₂ and T₃（P<0.05）（Table 3）.3 Ventilation Efficiency Variables.At T₂ and T₃,Pa O₂ was increased in the group PF compared with group VF（P<0.05）.Compared with group VI,at T₂ and T₃,Pa O₂ was increased in group PI（P<0.05）.In group VI,at T₂,Pa O₂ was increased compared with group VF and group PF（P<0.05）.Moreover,Pa O₂ was increased in group PI and group VI compared with group PF at T₃（P<0.05）.At T₂ and T₃,Pa O₂/Fi O₂ was increased in group PF and group PI compared with group VF（P<0.05）.And Pa O₂/Fi O₂ was increased in group PI compared with group VI at T₂ and T₃（P<0.05）.A-a DO₂ was decreased in group VI compared with group VF and group PF at T₂（P<0.05）.Compared with group VI,A-a DO₂ was decreased in group PI at T₂ and T₃（P<0.05）.Compared with group PF,A-a DO₂ was decreased in group PI at T₃（P<0.05）.Qs/Qt were decreased in group PF compared with group VF at T₂ and T₃（P<0.05）.At T₂,the Qs/Qt was decreased in group VI compared with group VF（P<0.05）.Compared with group VI,the Qs/Qt in the group PI were decreased at T₂ and T₃（P<0.05）.V_D/V_T was decreased in group PF,group VI,and group PI than in group VF at T₂.Moreover,V_D/V_T in group PI was lower than that in group VI and group VF（P<0.05）（Table 3）.4 Serum Concentration of CC16 and IL-6.There was no significant difference in the concentration of CC16 in the four groups at T₁（P>0.05）.The concentration of CC16 was decreased in the PI group compared with group VF,group PF and group VI,at T₃（P<0.05）.At T₃,the concentration of CC16 was decreased in the group PF and group VI compared with the group VF（P<0.05）.There was no significant difference in the concentration of IL-6 in the four groups（P>0.05）.The concentration of IL-6 was decreased in the group PF compared with the group VF at T₃（P<0.05）.Compared with groups VF and VI,the concentration of IL-6 in group PI was decreased（Table 4）.5 Other Clinical Endpoints.There was no significant difference in the incidence of high fever,cough and sputum.Also,there was no significant difference in the count of white blood cell and neutrophil within 72 hours after the operation in the four groups（P>0.05）（Table 5）.Conclusions During laparoscopic surgery in Trendelenburg position,the application of PCV-VG combined with individualized PEEP is beneficial to improve respiratory mechanics and ventilation efficiency and it can reduce the concentration of CC16 and IL-6in serum,and reduce lung injury.Figure2;Table6;Reference 140...