A bispectral index guided comparative evaluation of dexmedetomidine as an adjuvant to propofol-based total intravenous anaesthesia in spine surgeries done under motor-evoked potential monitoring

Abstract

Abstract Background The anaesthetic agents can affect the quality of motor-evoked potential intraoperatively as they inhibit synaptic transmission. Intravenous anaesthetics suppress motor-evoked potential lesser than inhalational agents, so total intravenous anaesthesia or a combination of intravenous with minimal inhalational anaesthetic supplementation is used when motor-evoked potential is monitored. Motor-evoked potential can get depressed at high doses of propofol required to maintain surgical depth, hence, adjuvant agents like dexmedetomidine that maintain anaesthetic depth without affecting the motor-evoked potential are often required. This study was a prospective non-randomized and comparative study (quasi-experimental) assigned into two groups of 64 each, labelled as the propofol group (group P) and Propofol + dexmedetomidine group (group PD). The primary objective of our study was to compare the total dose reduction of propofol with the addition of dexmedetomidine and their interference with motor-evoked potential readings. The secondary objective was to assess the hemodynamic changes, changes in amplitude and latency of motor-evoked potential, and complications if any. Results The mean total dose of propofol consumed in our study was 502.81 ± 71.01 mg in group propofol( P) and 392.18 ± 59.00 mg in group propofol + dexmedetomidine (PD). Moreover, the mean total dose of propofol (mg) was significantly less used in group PD. Intraoperative hemodynamic stability, no difference in amplitude and latency for motor-evoked potential, and only significant bradycardia in group propofol + dexmedetomidine (PD). Conclusions Dexmedetomidine can be successfully used in propofol-based total intravenous anaesthesia for motor-evoked potential monitoring in spine surgeries, but it is better to maintain stable hemodynamics with a significant reduction of the mean dose of propofol.