The Effects Of Somatosensory And Motor Evoked Potentials With Different Anesthesia On Neurophysiological Monitoring In Patients Undergoing Spinal Correction Surgery

Background:With the development of the technology in spinal surgery, there are more and more complex surgeries, in which intraoperative neurophysiological monitoring (IONM) become more commonly.During spinal surgery,somatosensory evoked potential (SEP) and motor evoked potential (MEP) are the most useful means to monitor the spinal cord function because of the simple operation and high accuracy.However, SEP and MEP are known to be particularly sensitive to the anesthetic factors.Objective:The aim of our study was to compare sevoflurane combined with propofol intravenous-inhalation anesthesia and propofol intravenous anesthesia as maintenance agents, focusing on hemodynamic stability, regained consciousness and the effects of SEP and MEP during surgery to correct scoliosis in adolescent patients of10-15years old.Patients:60adolescent patients with scoliosis who need monitor the spinal cord function during the surgery.Methods:Thirty adolescent patients,with a physical status according to American Society of Anesthesiologists(ASA) Ⅰ-Ⅱ,10-15y old,undergoing selective Scoliosis correction surgery were enrolled. Patients were randomly assigned to2equal groups,Group A propofol intravenous anesthesia and Group B sevoflurane combined with propofol intravenous-inhalation anesthesia.The induction of anesthesia are accomplished with intravenous in two groups.For group A, continuous intravenous infusion of propofol was used;while group B,inhalational anesthesia was maintained using a mean end-tidal sevoflurane concentration of1MAC combined with propofol. For analgesia, sufentanyl was given when required for both groups.We adjust the dose of propofol according bispectral index (BIS, which was maintained at45-55).We monitor and record the evoked potential’s amplitude and latency continuously. At the same time, the two groups of hemodynamic parameters were compared,the quality of patients regained consciousness and intraoperative awareness were assessed.Results:1、 There was no statistically significant difference between groups in the aspects of fundamental state (P>0.05) before surgery2、The two groups of patients hemodynamic parameters were very steady, the mean arterial pressure of propofol anesthesia is higher when compared with sevoflurane-propofol anesthesia, while the heart rate is lower but there was no statistically significant difference between groups in overall mean hemodynamic parameters (P>0.05)3、Sevoflurane-propofol anesthesia produced a decrease in SEP amplitude than propofol did(P<0.05);however,Sevoflurane-propofol anesthesia produced little effect on the latency of SEP(P>0.05).Reproducible MEP and SEP were obtained throughout the operation in all60cases. No differences in the incidence of postoperative recollection of operation were noted4、Postoperatively, there was a significant difference at the recovery time between sevoflurane-propofol anesthesia and propofol anesthesia for eye opening (mean10.5±6.8vsl9.8±9.8min) and tube removing(mean15.9±10.5vs25.4±13.3min), with the propofol group showing lower values, where more patients of the sevoflurane-propofol anesthesia seemed to be well orientedConclusions: A mean end-tidal sevoflurane concentration of1MAC combined with propofol anesthesia and propofol anesthesia for Scoliosis surgery provide safe results,both groups produced little effect on the evoked potential.which made hemodynamic stability and unawareness during the surgery. Sevoflurane-propofol anesthesia produces a faster recovery as well as a better evaluation for neurological function than propofol does.