Effect of dexmedetomidine on Nociception Level Index-guided remifentanil antinociception: A randomised controlled trial.

BACKGROUND: The effect of dexmedetomidine on Nociception Level Index-guided (Medasense, Israel) antinociception to reduce intra-operative opioid requirements has not been previously investigated. OBJECTIVE: We aimed to determine if low-dose dexmedetomidine would reduce remifentanil requirements during Nociception Level Index-guided antinociception without increasing complications associated with dexmedetomidine. DESIGN: Double-blind randomised controlled trial. SETTING: Two university teaching hospitals in Brussels, Belgium. PATIENTS: American Society of Anesthesiologists 1 and 2 patients (n = 58) undergoing maxillofacial or cervicofacial surgery under propofol--remifentanil target-controlled infusion anaesthesia. INTERVENTIONS: A 30 min infusion of dexmedetomidine, or equal volume of 0.9% NaCl, was infused at 1.2 µg kg-1 h-1 immediately preceding induction and then decreased to 0.6 µg kg-1 h-1 until 30 min before ending surgery. Nociception Level Index and frontal electroencephalogram guided the remifentanil and propofol infusions, respectively. MAIN OUTCOMES: The primary outcome was the remifentanil requirement. Other outcomes included the propofol requirement, cardiovascular status and postoperative outcome. RESULTS: Mean ±â€ŠSD remifentanil (3.96 ±â€Š1.95 vs. 4.42 ±â€Š2.04 ng ml-1; P = 0.0024) and propofol (2.78 ±â€Š1.36 vs. 3.06 ±â€Š1.29 µg ml-1; P = 0.0046) TCI effect site concentrations were lower in the dexmedetomidine group at 30 min postincision and remained lower throughout surgery. When remifentanil (0.133 ±â€Š0.085 vs. 0.198 ±â€Š0.086 µg kg-1 min-1; P = 0.0074) and propofol (5.7 ±â€Š2.72 vs. 7.4 ±â€Š2.80 mg kg-1 h-1; P = 0.0228) requirements are represented as infusion rates, this effect became statistically significant at 2 h postincision. CONCLUSION: In ASA 1 and 2 patients receiving Nociception Level Index-guided antinociception, dexmedetomidine decreases intra-operative remifentanil requirements. Combined frontal electroencephalogram and Nociception Level Index monitoring can measure dexmedetomidine's hypnotic and opioid-sparing effects during remifentanil-propofol target-controlled infusion anaesthesia. TRIAL REGISTRATIONS: Clinicaltrials.gov: NCT03912740, EudraCT: 2018-004512-22.