Plasma concentration of dexmedetomidine combined with fixed remifentanil for nociceptive and hemodynamic control during skull pin fixation

of dexmedetomidine at 0.325 ng/mL and 0.395 ng/mL, respectively, for maintaining nociceptive and hemodynamic stability. Dexmedetomidine Cp below 0.3 ng/mL were associated with greater fluctuations in ANI, MAP, and HR. ANI < 30 demonstrated a sensitivity of 81.8% and a specificity of 100% for detecting analgesic failure. These findings suggest that when remifentanil is maintained at a Ce of 2.0 ng/mL, a dexmedetomidine Cp of 0.395 ng/mL provides optimal nociceptive and hemodynamic control during skull pin fixation, supporting the use of individualized dexmedetomidine titration and ANI-guided multimodal monitoring in neurosurgical anesthesia.