Effects Of Cdyn Guided Individualized PEEP On Intraoperative Pulmonary Function Of Patients Undergoing Robotic-assisted Laparoscopic Radical Prostatectomy

Objective:To evaluate the effects of a dynamic lung compliance(Cdyn)based individualized PEEP on intraoperative pulmonary function of patients undergoing robotic-assisted laparoscopic radical prostatectomy.Method: Forty patients aged 65-80 with BMI of 19-28 kg/m2 and ASA classification of II or III scheduled for robotic-assisted laparoscopic radical prostatectomy were randomly divided into two groups(n=20): control group(group C)and PEEP group(group P).Except for PEEP,each group of patients ventilated in the same strategy after tracheal intubation.Patients in group P received an incremental PEEP titration from the lowest PEEP available in the anesthesia machine,increased 2 cm H2 O every 4 min,until maximal Cdyn achieved.Such titrations would be performed twice during the procedure: just after tracheal intubation and establishment of Trendelenburg position and pneumoperitoneum.Patients in group C received no external PEEP during procedure.For patients of group P,PIP,Pa O2,Pa CO2 and PETCO2 would be recorded,and arterial blood(obtained from radical arterial catheter)gas analysis would be performed at the following 5 time points: 4 min after the first PEEP titration(T1);4 min after the second PEEP titration(T2);1 hrs after T2(T3);2 hrs after T2(T4);and 1 min after the closure of abdominal cavity(T5).For patients of group C,all the same parameters of group P would be recorded at the following 5 time points: 4 min after tracheal intubation(T1);4 min after onset of Trendelenburg position and pneumoperitoneum(T2);1 hrs after T2(T3);2 hrs after T2(T4);and 1 min after the closure of abdominal cavity(T5).Oxygenation index(OI),driving pressure(DP),difference between oxygen partial pressure of alveolar and arteria(A-a DO2),and ratio of physical dead space to tidal volume(Vd/Vt)were calculated at each time point of both groups.Result: The median(IQR)PEEP of the first titration is 6.0(5.5-8)cm H2 O and the second of it is 8(6-9)cm H2 O.OI and Pa O2 were increased,while DP and A-a DO2 were decreased during procedures in group P compared with group C(P<0.05).Meanwhile,peak airway pressure,Vd/Vt and Pa CO2 showed no significant difference in group P compared with group C(P>0.05).Conclusion: For patients undergoing robotic-assisted laparoscopic radical prostatectomy in Trendelenburg position,Cdyn based individualized PEEP can improve lung compliance,decrease driving pressure and optimize oxygenation.Thus,the pulmonary function during the procedure is improved.