The Correlation Between The Area Under The Bis Curve And Early Cognitive Function In Elderly Patients Undergoing Thoracoscopic Surgery

Objective:To explore the effects of maintaining different depth of anesthesia under BIS monitoring on early postoperative cognitive function in elderly patients undergoing thoracoscopic surgery（VATS）,and to explore the risk factors associated with early postoperative cognitive dysfunction（POCD）by multivariate Logistic regression analysis.Methods:A total of 80 patients,aged≥65 years,had ASA grades in I～Ⅲ,who underwent thoracoscopic surgery in the First Affiliated Hospital of Hebei North University from December 2021 to July 2022were selected and divided into group D（deep anesthesia group）and Group L（light anesthesia group）by random number table method.The depth of anesthesia was regulated by BIS,which was 35～45 in the deep anesthesia group and 45～55 in the light anesthesia group.The patients’cognitive function was scored by the Simple Mental State Scale（MMSE）before surgery,1 day after surgery,3 days after surgery,and 7 days after surgery,respectively.POCD was judged to have occurred if the postoperative MMSE score was less than 24 points,or the postoperative score decreased by more than 2 points compared with the preoperative score.Preoperative general conditions of the two groups of patients were recorded,including mean arterial pressure（MAP）,heart rate（HR）,pulse oxygen saturation（Sp O2）and BIS values at the moment of entering the operating room（T₀）,the moment of completion of anesthesia induction（T₁）,the moment of operation beginning（T₂）,the moment of anesthetic cessation（T₃）,and the moment of tracheal catheter removal（T₄）.Anesthesia time,single lung ventilation time,recovery time,orientation recovery time,propofol dosage,remifentanil dosage,infusion volume,blood loss,urine volume,and the number of cases of POCD were counted.Venous blood was collected from patients before surgery,end of surgery,1 day and 3 days after surgery,and the concentrations of serum interleukin 6（IL-6）,S100βprotein and neurons-pecific enolase（NSE）were detected by enzyme-linked immunoassay（ELISA）.We will sort out the BIS data stored in the EEG bispectral index monitor,calculate the area under the BIS curve from and the mean BIS from T₁to T₃,and analyze the risk factors for POCD by multivariate logistic regression.Results:71 cases were actually included in this study,including 35cases in group D（deep anesthesia group）and 36 cases in group L（shallow anesthesia group）.The incidence of POCD was 31%.There was no significant difference in the occurrence of POCD 1 day and 3 days after surgery between the two groups（p>0.05）,and the incidence of POCD in group D was lower than that in group L（p<0.05）.Propofol dosage,recovery time and orientation recovery time of group D were higher than those of group L（p<0.05）.In T₁-T_3,the mean value of BIS and the area under BIS curve in group D were significantly lower than those in group L（p<0.01）.IL-6,S100βprotein and NSE in group D were lower than those in group L at the end of surgery,1 day after surgery and 3 days after surgery,with statistical significance（p<0.05）.Logistic regression analysis showed that age,years of education,area under BIS curve and S100βprotein concentration 1 day after surgery were risk factors for early POCD in elderly patients undergoing thoracoscopic surgery.Conclusion:Early postoperative cognitive dysfunction is a common complication in elderly patients undergoing thoracoscopic surgery.Deep anesthesia can reduce postoperative inflammatory response,reduce brain injury and improve early postoperative cognitive function in elderly patients undergoing thoracoscopic surgery.In addition to age,years of education,and S100βprotein concentration 1 day after surgery,BIS area under the curve was also a risk factor for early POCD in elderly patients undergoing thoracoscopic surgery.