Effect of dexmedetomidine on evoked‐potential monitoring in patients undergoing brain stem and supratentorial cranial surgery

Abstract

Background Dexmedetomidine is used as adjuvant in total intravenous anaesthesia (TIVA), but there have been few studies concerning its effect on intraoperative neurophysiological monitoring (IONM) during cranial surgery. Our aim was to study the effect of dexmedetomidine on IONM in patients undergoing brain stem and supratentorial cranial surgery. Methods Two prospective, randomized, double‐blind substudies were conducted. In substudy 1, during TIVA with an infusion of propofol and remifentanil, 10 patients received saline solution (SS) (PR group) and another 10 (PRD group) received dexmedetomidine (0.5 mcg/kg/h). Total dosage of propofol and remifentanil, intensity, latency and amplitude of motor‐evoked potentials following transcranial electrical stimulation (tcMEPs) as well as somatosensory‐evoked potentials (SSEP) were recorded at baseline, 15, 30, 45 minutes, and at the end of surgery. In order to identify differences in the same patient after dexmedetomidine administration, we designed substudy 2 with 20 new patients randomized to two groups. After 30 minutes with TIVA, 10 patients received dexmedetomidine (0.5 mcg/kg/h) and 10 patients SS. The same variables were recorded. Results In substudy 1, propofol requirements were significantly lower (P = .004) and tcMEP intensity at the end of surgery was significantly higher in PRD group, but no statistically significant differences were observed for remifentanil requirements, SSEP and tcMEP latency or amplitude. In substudy 2, no differences in any of the variables were identified. Conclusions The administration of dexmedetomidine at a dosage of 0.5 mg/kg/h may reduce propofol requirements and adversely affect some neuromonitoring variables. However, it can be an alternative on IONM during cranial surgeries. REDEX EudraCT: 2014‐000962‐23

Comparison of Dexmedetomidine Versus Fentanyl-Based Anesthetic Protocols Under Patient State Index Guidance in Patients Undergoing Elective Neurosurgical Procedures with Intraoperative Neurophysiological Monitoring

“…Lee et al [ 36 ] in their study observed that the baseline amplitude was lower in the dexmedetomidine group and required higher stimulation currents for achieving the baseline values. Similar requirements of higher stimulation intensities were also observed in the study by Pacreu et al [ 35 ] in cranial surgeries without significantly affecting the amplitude and latency of SSEPs and MEPs. These did not hinder the correct interpretation of the responses throughout the surgery.…”

“…The mean propofol consumption was lower in the dexmedetomidine group (101.4 ± 13.5 µg/kg/min) when compared to the fentanyl group (148 ± 29.8 µg/kg/min) by approximately 30% and was statistically significant (p < 0.001) (Table 2). Our finding was at par with other studies, demonstrating a propofol-sparing effect of dexmedetomidine due to its α-2 agonist activity on the locus ceruleus [12][13][14][15]19,28,29,[30][31][32][33][34][35][36][37][38][39]. Chakrabarti et al [33] reported similar findings in patients undergoing cerebellopontine angle surgeries with TIVA when dexmedetomidine was used as an adjuvant.…”

“…The requirement for additional intraoperative fentanyl boluses was comparable between the two groups in our study (Table 2 ). The majority of the studies on TIVA employ a propofol-opioid combination as the standard regimen [ 16 , 35 ]. Our study differs from those studies, as the opioid (fentanyl) is not a part of the standard TIVA regime in either of the groups.…”

Multimodal Analgesia and Intraoperative Neuromonitoring

“…In a retrospective case-controlled study of 70 pediatric patients undergoing posterior spine surgery, dexmedetomidine infusion at 0.3 to 0.5 mcg/kg/h without bolus was associated with a statistically and clinically significant reduction in TcMEP amplitude from baseline. 22 In a prospective, double-blinded RCT by Pacreu et al, 23 40 patients undergoing intracranial tumor resections were randomized to receive either dexmedetomidine 0.5 mcg/kg/h infusion without bolus or normal saline infusion, in addition to propofol and remifentanil infusions for anesthesia maintenance; 23 TcMEP stimulation threshold was significantly higher in the dexmedetomidine group, though the TcMEP and SSEP amplitudes were not different between the 2 groups. In a double-blinded RCT involving 160 patients undergoing thoracic spine surgery, participants were randomized to receive either dexmedetomidine 1 mcg/kg bolus followed by 0.5 mcg/kg/h infusion, dexmedetomidine 0.5 mcg/kg/h infusion without bolus, or placebo infusion.…”

Effects of dexmedetomidine on evoked potentials in spinal surgery under combined intravenous inhalation anesthesia: a randomized controlled trial

“…As a result, spinal surgery benefits from combined intravenous inhalation anesthesia. As an adjuvant, dexmedetomidine (Dex) may be useful in reducing the need for propofol [ 9 , 10 ]. For example, the induction dose of propofol can be reduced by 15% and the demand for propofol can be reduced by 29% by adding Dex to TIVA [ 11 ].…”