Efficacy Of Local Cerebral Oxygen Saturation Combined With Neurophysiological Monitoring On Blood Pressure Management In Patients Undergoing Carotid Endarterectomy

Objective: To investigate the efficacy of local cerebral oxygen saturation combined with neurophysiological monitoring on blood pressure management during blocking the ipsilateral carotid artery in patients undergoing carotid endarterectomy and to provide a clinical reference.Methods: Forty patients of both sexes,aged 50-80 years old,of American Society of Anesthesiologists physical status or Ⅱ Ⅱ,scheduled for elective carotid endarterectomy,were randomly divided into 2 groups: control group（group C,n=20）and multiple monitoring group（group M,n=20）.In group C,blood pressure was increased by 20%-30% of the baseline before operation according to traditional method.Systolic blood pressure was adjusted based on rSO₂ and neurophysiological monitoring to maintain monitoring indicators within the scope of clinical changes in the group M.After entering the operating room,noninvasive blood pressure（NIBP）,heart rate（HR）,electrocardiogram（ECG）,pulse oxygen saturation（Sp O2）,rSO₂ and bispectral index（BIS）were monitored,and the radial artery was punctured under local anesthesia,the Flo Trac/vigileo was connected to monitor and record arterial blood pressure（IBP）,cardiac output（CO）and stroke volume variation（SVV）.The same induction was carried out in all the patients,anesthesia was induced with intravenous injection of midazolam 0.01-0.05 mg/kg,etomidate 0.1-0.3 mg/kg,cisatracurium 0.1-0.2 mg/kg,sufentanil citrate 0.4-0.6 g/kg and lidocaine 60-100 mg.Anesthesia was maintained by micro pump continuous infusion at a rate of propofol 2-6 mg·kg-1·h-1,remifentanil 0.1-0.3 μg·kg-1·min-1 to maintain the BIS value between 40-60.After induction,electrophysiological machine was connected to monitor EEG and somatosensory evoked potentials by electrophysiology doctors.In the carotid artery block period,vasoactive drugs were administered to increase systolic blood pressure by 20%-30% of baseline in group C,and rSO₂ and neurophysiological monitoring were used in group M.The baseline characteristics of patients including age,sex,education level,preoperative complications were evaluated,and cognitive function was assessed with the mini mental state examination（MMSE）before operation.Blood pressure was monitored and recorded at 6 time points as follows: ward nurses measured mean blood pressure in the morning every day（T0,baseline）,immediately after intubation（T1）,when blood pressure was stable after anesthesia induction（T2）,five minutes after blocking the carotid artery（T3）,five minutes after opening the carotid artery（T4）,at extubation（T5）.rSO₂ recorded after admission to the operating room（T0）served as baseline,and rSO₂ was recorded at T1-5.The postoperative blood pressure was recorded at follow-up.The consumption of general anesthetics and vasoactive drugs,the time of blocking,emergence time,extubation time and complications after operation were recorded.Cognitive function was assessed with Mini-Mental State Examination（MMSE）on the 1st day,the 3rd day and the 7th day after operation.Results:1 There was no significant difference in the age,gender,education level,preoperative complications and other general information between two groups（P>0.05）.2 There was no statistically significant difference in the blood pressure at T0-2 and T4,5 between the two groups（P>0.05）,however,significant changes in the blood pressure were found at T3（P<0.05）.Compared with group C,four patients in group M had elevated blood pressure by 10%-20%,blood pressure was increased in eleven patients by 0%-10% and lower than baseline blood pressure in five patients.Compared with baseline at T0,the blood pressure dropped at T2,4,5 and increased at T1,3,and the difference was statistically significant in the two groups（P<0.05）.3 There was no statistically significant difference between the two groups in rSO₂ at the 6 time points（P>0.05）,the rSO₂ at T1 was the highest and the rSO₂ at T3 was the lowest.The rSO₂ decreased by 9.7% in the group C and by 10% in the group M at T3.After opening the carotid artery,the rSO₂ returned to the level before occlusion and was still slightly higher than the level at T2（until T5）.4 There was no significant difference between the two groups in preoperative MMSE score（P>0.05）.MMSE scores of the patients decreased on the 1st day and 3rd day after operation and returned to the preoperative level on the 7th day after operation in the two groups.The incidence of postoperative cognitive dysfunction was 20% in group C and 15% in group M on the 1st day after operation,10% in group C and 15% in group M on the 3rd day after operation,and 5% in group C and 0% in group M on the 7th day after operation.5 Compared with group C,the frequency and dose of vasoactive drugs,RPP in the blocking period were decreasd in group M（P<0.05）.There was no significant difference between the two groups in the consumption of anesthetics,blocking time,emergence time,extubation time and complications after operation（P>0.05）.Conclusions:Cerebral oxygen saturation combined with neurophysiological monitoring plays a guiding role in blood pressure management during carotid artery occlusion.It’s more accurate and safe than traditional methods,reducing cardiac work,and does not reduce postoperative cognitive function.