Comparison of dexmedetomidine with ketamine for their effects on amplitude of motor evoked potential intraoperatively

Abstract

Intraoperative motor evoked potential monitoring is commonly used during spinal surgeries as it reduces incidence of neurological damage and have better post-operative neurological outcome. Anaesthetic agents cause a dose dependent inhibition of evoked potential responses while ketamine and dexmedetomidine are said to have minimal effect. We planned this study to compare effect of dexmedetomidine and ketamine on MEP. Materials and Methods: All patients induced using glycopyrrolate, fentanyl, propofol and no anxiolytics and intubated with succinylcholine 2mg /kg, maintenance done with propofol infusion@ 60 mg/hr in both groups. Group-D-received dexmedetomidine 0.5mg/kg and Group-K-received ketamine 0.6mg/kg in 100ml NS over a period of 10mts.Electrodes were placed above the level of surgical intervention for MEP and TOF recording. Baseline MEP recorded and after completion of infusion of the study drugs was taken as 0 min, then the MEP was recorded at every 5 min till 30 min. Results: In our study we observed that amplitude of MEP was statistically significant (p value 0.009 at 15 minutes) and was higher in ketamine group than dexmedetomidine group. Conclusion: We concluded that both agents are equally good as they cause minimal depression and are equally efficient in measuring the amplitude of MEP.