Effects Of Different PEEP Levels On Cerebral Oxygen Saturation In Elderly Patients With Laparoscopic Colorectal Cancer

ObjectiveTo explore the effects of non-PEEP,5cm H₂O PEEP,and individualized optimal PEEP on local cerebral oxygen saturation（r SO₂）in elderly patients during laparoscopic colorectal cancer surgery.Methods1.Select 90 elderly patients from the People’s Hospital of Inner Mongolia Autonomous Region who underwent elective laparoscopic radical resection of colorectal cancer between December2019 and December 2020,aged 60 to 70 years,regardless of gender,BMI 18-25 kg/m²,ASA Grade I-III,good liver and kidney function,no history of serious heart and lung diseases before surgery,no history of lung surgery,recent history of upper respiratory tract infection and history of immunosuppressant use,no history of mental illness,brain trauma,and cerebrovascular disease,No thoracic and spinal deformities.The patients were divided into 3groups（n=30）by the digital random table method:Group A PEEP=0cm H₂O,Group B PEEP=5cm H₂O,Group C PEEP value is the most suitable PEEP under the titration method,and the three groups of ventilation modes all use pressure to control the volume.Guaranteed ventilation（Pressure controlled ventilation-volume guaranteed,PCV-VG）mode.3.The three groups A,B,and C were respectively in the supine position before anesthesia induction intubation（T0）,10 minutes after the supine anesthesia induction intubation（T1）,30minutes after the head-down pneumoperitoneum（T2）,and after the head-down pneumoperitoneum 60min（T3）,at the end of the operation（T4）,10min after extubation（T5）r SO₂,mean arterial pressure（MAP）;record airway plateau pressure（Airway plateau pressure,MAP）at T1,T2,T3,and T4 Pplat)and Cdyn;Collect arterial blood samples at T0,T3,and T5,use a blood gas analyzer to detect blood gas indicators,and record PH,partial pressure of oxygen（Pa O2）,and partial pressure of carbon dioxide（Pa CO2）.results1.The general conditions of the three groups of patients,such as gender,age,BMI,operation time,pneumoperitoneum time,and fluid infusion,showed no significant difference（P>0.05）.2.r SO2:Compared with T0,patients in groups A,B,and C all increased at T2 and T3,and the difference was statistically significant（P<0.05）;at T2,T3,compared with group A,patients in group C had r SO2 The difference was statistically significant（P<0.05）.There was no significant change in r SO2 in group B（P>0.05）.3.MAP:Compared with T0,the three groups of patients all decreased at T1,T2,T3,and T4.Compared with T5,the three groups of patients all decreased at T1,T2,T3,and T4,and the difference was statistically significant（P<0.05）.During the whole period,the difference in MAP of the three groups of patients was not statistically significant（P>0.05）.4.Pplat:Compared with T1,the three groups of patients decreased in T2 and T3,and the difference was statistically significant（P<0.05）.During the whole period,there was no statistically significant difference in Pplat among the three groups of patients（P>0.05）.5.Cdyn:Compared with T1,patients in groups A,B,and C all decreased at T2,T3,and T4,and the difference was statistically significant（P<0.05）;at T2,T3,compared with group C,A,Cdyn of patients in group B decreased（P<0.05）;at T4,compared with group A,both groups B and C increased.Compared with group B,Cdyn of patients in group C increased significantly,and the difference was statistically significant.（P<0.05）.6.Blood gas indicators:Pa CO2:Compared with T0,the three groups A,B,and C all increased at T3,and the difference was statistically significant（P<0.05）;at T0 to T5,there was no statistically significant difference in Pa CO2 between the three groups（P>0.05）.Pa O2:Compared with T0,Pa O2 of the three groups A,B,and C increased at T3 and T5,and the difference was statistically significant（P<0.05）;at T5,compared with group A,group B and group C Both were increased,and the difference was statistically significant（P<0.05）.PH:From T0 to T5,there was no significant difference in Pa CO2 between the three groups（P>0.05）.conclusion1.Compared with group A,small tidal volume combined with individualized PEEP（group C）can increase r SO₂,increase lung compliance and Pa O₂;therefore,individualized PEEP can be safely used in laparoscopic surgery for elderly patients with colorectal cancer.2.Compared with group A,PEEP=5 cm H2O（group B）can increase Pa O₂and increase lung compliance.3.Compared with PEEP=5 cm H₂O（group B）,small tidal volume combined with individualized PEEP（group C）can increase the lung compliance of elderly patients with laparoscopic colorectal cancer and reduce the incidence of lung injury.