Effects Of Sevoflurane Combined With Dexmedetomidine On Postoperative Cognitive Function In Patients Undergoing Radical Resection Of Esophageal Cancer

Background:Postoperative cognitive dysfunction（POCD）is one of the common surgical anesthesia complications characterized by memory,attention,language comprehension,information processing and social impairment.The incidence rate is as high as 5%-15%.POCD has a negative impact on the patient’s physical and mental health and can even increase patient mortality.Therefore,how to reduce the incidence is very important.Studies have confirmed that advanced age is a major risk factor for the onset of POCD.Therefore,the incidence of POCD in elderly patients is particularly significant.Sevoflurane is the most commonly used inhaled anesthetic in the clinic,and its differential effects on cognitive function are related to drug concentration and duration of action.The occurrence of POCD is related to cerebral oxygen saturation（rSO₂）,but the pathogenesis is not clear.Dexmedetomidine has sedative,analgesic,anti-anxiety,anti-sympathetic effects,can effectively reduce intraoperative cerebral oxygen metabolism,reduce the decline of rSO₂ during single-lung ventilation in elderly thoracic surgery patients,and reduce the incidence of POCD.This study was to compare the effects of sevoflurane,sevoflurane combined with propofol and sevoflurane combined with dexmedetomidine on cognitive function in elderly patients undergoing radical nephrectomy under general anesthesia,and provide a reference basis for clinical application.Objective:This study was to investigate the effects of sevoflurane combined with dexmedetomidine on regional cerebral oxygen saturation and postoperative cognitive function in patients undergoing radical resection of esophageal cancer,thus providing a reference for clinical prevention and treatment of postoperative brain complications in patients undergoing such surgery.Methods:A total of 90 patients aged 65-78 years old,undergoing adical nephrectomy,were enrolled and allocated into three groups:sevoflurane（S group）,sevoflurane with dexmedetomidine（SD group）and sevoflurane with propofol（SP group）,30 cases per group.The anesthetic inducing drugs were the same in the three groups.Sevoflurane of 1-1.5 minimum alveolar concentration（MAC）was maintained for the anesthesia in S group.Sevoflurane of 0.5 MAC was maintained for the anesthesia,meanwhile,dexmedetomidine with a load dosage of 1μg/kg was pumped and finished within 10min,and then dexmedetomidine with a dosage of 0.2-0.4μg·kg^-1·h^-11 was intravenously pumped until 30 min before the operation completed in SD group.Sevoflurane of 0.5 MAC was maintained for the anesthesia,and target control infusion（TCI）of propofol was performed and the plasma concentration of 2-3μg/ml of propofol was kept in SP group.Regional cerebral oxygen saturation（rSO₂）was determined by using NI/RO-200 cerebral oxygen saturation monitor respectively 10min before the anesthesia（T₀）,10 min after the anesthesia（T₁）,10 min before the surgery started（T₂）,10 min（T₃）,30 min（T₄）and 60 min（T₅）after the surgery started,10 min before the operation finished（T₆）,at the set of the operation finished（T₇）in the three groups.The levels of plasma tumor necrosis factor alpha（TNF-α）,interleukin-6（IL-6）and IL-8 and the concentrations of astrocyte S-100βprotein（S-100βprotein）and neuron specific enolase（NSE）were measured by enzyme-linked immunosorbent assay（ELISA）10 min before the surgery started and1st,3rd and 7th postoperatively,respectively.Cognitive function tests were performed in the three groups of patients with preoperative 3 day and 3 day,7 day,and 30 day postoperatively using the Concise Mental State Scale（MMSE）and the Montreal Cognitive Assessment（MoCA）,and the incidence of POCD was calculated.Results:1.Compared with T₀,rSO₂ at T₁-₂ and T₆-₇ was higher（all P<0.05）in the three groups,while rSO₂ at T₃-₅ was lower（all P<0.05）in S group and SP group,and rSO₂at T₄-₅ was lower（all P<0.05）in SD group.Compared with S group and SP group,rSO₂ at T₃-₅ was higher（all P<0.05）in SD group.2.Compared with 10 min before the surgery started,the levels of plasma TNF-α,IL-6 and IL-8 were increased in the three groups on the 1st,3rd and 7th day after surgery（P<0.05）.Compared with S group,the levels of plasma TNF-α,IL-6 and IL-8in SP group were decreased on the 1st,3rd and 7th day after surgery（P<0.05）.Compared with SP group,the levels of plasma TNF-α,IL-6 and IL-8 in SD group were decreased on the 1st,3rd and 7th day after surgery（P<0.05）.3.Compared with 10 min before the surgery started,the concentrations of plasma S-100βprotein and NSE were increased in the three groups on the 1st,3rd and 7th day after surgery（P<0.05）.Compared with S group,the concentrations of plasma S-100βprotein and NSE in SP group were decreased on the 1st,3rd,and 7th postoperative days（P<0.05）.Compared with SP group,the concentrations of plasma S-100βprotein and NSE in SD group were decreased on the 1st,3rd,and 7th postoperative days（P<0.05）.4.Compared with preoperative 3 day,MMSE and MoCA were decreased in the three groups on the 3rd,7th day and 30th day after surgery（P<0.05）.Compared with S group,MMSE and MoCA were increased in SP group on the 3rd,7th and 30th postoperative day（P<0.05）.Compared with SP group,MMSE and MoCA were increased in SD group on the 3rd,7th and 30th postoperative days（P<0.05）.5.The occurrence rate of POCD was calculated as follows:10 cases had POCD in S group,and the occurrence rate was 33.3%,9 cases had POCD in SP group,and the occurrence rate was 30.0%,and 3 cases had POCD in SD group,and the occurrence rate was 10.0%.Compared with S group and SP group,the occurrence rate was lower in SD group（P<0.05）.Conclusion:1.Sevoflurane combined with dexmedetomidine can increase rSO₂,thereby reducing the incidence of POCD in elderly patients undergoing radical esophageal cancer.2.Sevoflurane combined with dexmedetomidine can reduce the incidence of POCD by reducing plasma TNF-αand IL-6 concentrations.