RESUMO
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 (nâ=â58) undergoing maxillofacial or cervicofacial surgery under propofol--remifentanil target-controlled infusion anaesthesia. INTERVENTIONS: A 30âmin infusion of dexmedetomidine, or equal volume of 0.9% NaCl, was infused at 1.2âµgâkg-1âh-1 immediately preceding induction and then decreased to 0.6âµgâkg-1âh-1 until 30âmin 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: Meanâ±âSD remifentanil (3.96â±â1.95 vs. 4.42â±â2.04ângâml-1; Pâ=â0.0024) and propofol (2.78â±â1.36 vs. 3.06â±â1.29âµgâml-1; Pâ=â0.0046) TCI effect site concentrations were lower in the dexmedetomidine group at 30âmin postincision and remained lower throughout surgery. When remifentanil (0.133â±â0.085 vs. 0.198â±â0.086âµgâkg-1âmin-1; Pâ=â0.0074) and propofol (5.7â±â2.72 vs. 7.4â±â2.80âmgâkg-1âh-1; Pâ=â0.0228) requirements are represented as infusion rates, this effect became statistically significant at 2âh 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.