Effect Of Dexmedetomidine On Brain Protection And Early Cognitive Function In Patients Undergoing Meningioma Resection

Objective:To investigate the effects of dexmedetomidine on brain protection and early postoperative cognitive function in patients undergoing meningioma resection and its possible mechanism.Methods:Sixty patients undergoing meningioma resection,male or female,aged18-65 years,ASA I or II,were randomly divided into two groups（n=30）:dexmedetomidine group（group D）and control group（group C）.The group D received a loading dose of 1.0μg/kg dexmedetomidine for the initial 10 minutes,and switched to a continuous intravenous infusion rate of 0.4μg/kg/h respectivly before anesthesia.The continuous infusion rate stoped in 30 minutes before the surgery was completed.The group C received the same rate of saline.The mean arterial pressure（MAP）and heart rate（HR）were observed and recorded before injection of dexmedetomidine or saline（T₀）,5 minutes after induction of anesthesia（T₁）,immediately after tracheal intubation（T₂）,scalp incision（T₃）,skull drilling（T₄）,end of operation（T₅）,extubation（T₆）,and the adverse reactions during operation were recorded.The 3 ml blood of the center venous was collected at 30 minutes before induction of anesthesia（t₁）,end of operation（t₂）and 24 hours after operation（t₃）.The serum levels of brain injury markers（NSE,S100β）,inflammatory factors（TNF-α,IL-6）and oxidative stress indexes（SOD,MDA）were detected after sufficient specimen collection.Before operation,3 days and 7 days after operation,the cognitive status of patients was estimated by MMSE,WAIS and WMS.The incidence rate of POCD was then compared between the two groups.Results:There was no significant difference in preoperative general data and intraoperative general information between the two groups（P>0.05）.Comparison of MAP between the two groups showed that the value of MAP at T₁ was lower than at T₀（P<0.05）.The values of MAP at T₂,T₃,T₄,T₅ and T₆ in the two groups were higher than at T₁（P<0.05）.The values of MAP in group D at T₂,T₃,T₄,T₅ and T₆ were lower than in group C（P<0.05）.Comparison of HR between the two groups showed that the value of HR at T₁ was lower than at T₀（P<0.05）.The values of HR at T₂,T₃,T₄ and T₆ in the two groups were higher than at T₁（P<0.05）.The values of HR in group D at T₂,T₃,T₄ and T₆ were lower than in group C（P<0.05）.The incidence of hypertension and tachycardia in group D was significantly lower than in group C（P<0.05）.There was no significant difference in the incidence of hypotension and bradycardia between the two groups（P<0.05）.Comparison of brain injury markers between the two groups indicated that levels of NSE and S100βat T₂ and T₃ were higher than at T₁（P<0.05）.The levels of NSE and S100βat T₂ and T₃ in group D were lower than in group C（P<0.05）.Comparison of inflammatory factors between the two groups showed that levels of TNF-αand IL-6 at T₂ and T₃ were higher than at T₁（P<0.05）.The levels of TNF-αand IL-6 in group D at T₂ and T₃ were lower than in group C（P<0.05）.Comparison of oxidative stress indexes between the two groups showed that levels of SOD at T₂ and T₃ were lower than at T₁（P<0.05）.The levels of MDA at T₂ and T₃were higher than at T₁（P<0.05）.The levels of SOD in group D at T₂ and T₃ were higher than in group C（P<0.05）.The levels of MDA in group D at T₂ and T₃ were lower than in group C（P<0.05）.Comparison of cognitive function evaluation between the two groups showed that the scores of each test item in the two groups decreased significantly on the 3rd day after operation compared with 1 day before operation（P<0.05）.The scores of multiple test items in the two groups recovered on the 7th day after operation,but were still significantly lower than those before operation（P<0.05）.Compared with group C,the scores of multiple test items in group D increased significantly on the 3rd day after operation（P<0.05）.There was no significant difference in the scores of each test item between the two groups on the7th day after operation（P<0.05）.The incidence of POCD in group D was significantly lower than that in group C on the 3rd day after operation（P<0.05）.There was no significant difference in the incidence of POCD between the two groups on the 7th day after operation（P<0.05）.Conclusion:（1）Dexmedetomidine can reduce the levels of serum NSE and S100βin patients undergoing meningioma resection,and has brain protective effect.（2）Dexmedetomidine may play a protective role in brain by inhibiting inflammation and oxidative stress in patients undergoing meningioma resection and reduce the incidence of POCD 3 days after operation.