Intrathecal Anesthesia

Objective: To investigate the temporal dynamics of dexmedetomidine's analgesic effects in the brain using EEG. Methods: Eligible patients scheduled for total hip arthroplasty under intrathecal anesthesia received a continuous infusion of DEX at 1.5 μg/(kg·h) for 15 minutes before neuraxial puncture, followed by an additional 15-minute infusion. The study was divided into three phases: Phase 1: Non-dosing phase (Baseline). Phase 2: DEX preemptive analgesia phase (DEX infusion). Phase 3: DEX cessation phase (Post-infusion). Outcomes: Primary safety outcome: EEG spectral analysis at different phases. Secondary outcomes: NRS scores, postoperative nausea and vomiting (PONV), dizziness, agitation, and time to intestinal exhaust within 48 hours. Intraoperative hemodynamics were also monitored.