Intravenous Dexmedetomidine as a Perioperative Autonomic-Immune Neuromodulator

Surgical trauma induces activation of the sympathetic nervous system and triggers a systemic inflammatory response that may adversely affect postoperative recovery. Dexmedetomidine, a highly selective α2-adrenoceptor agonist, has been proposed as a pharmacological neuromodulatory strategy capable of attenuating sympathetic activation and modulating neuroimmune interactions during the perioperative period. However, the extent to which intravenous dexmedetomidine influences perioperative inflammatory biomarkers and clinical recovery in patients undergoing total hip arthroplasty under regional anesthesia remains unclear. This prospective, randomized, double-blind, placebo-controlled trial aims to evaluate the effects of two doses of intravenous dexmedetomidine administered during spinal anesthesia combined with ultrasound-guided pericapsular nerve group (PENG) block on autonomic regulation, systemic inflammatory response, postoperative pain, opioid consumption, and quality of recovery following elective primary total hip arthroplasty.

Inclusion Criteria: * Adults aged 50-90 years. * Scheduled for elective primary total hip arthroplasty due to primary hip osteoarthritis. * American Society of Anesthesiologists (ASA) physical status I-III. * Planned spinal anesthesia combined with ultrasound-guided Pericapsular Nerve Group (PENG) block. * Ability to understand the study procedures and provide written informed consent. Exclusion Criteria: * Refusal to participate or inability to provide written informed consent. * Contraindications to spinal anesthesia. * Contraindications to PENG block. * Allergy or hypersensitivity to dexmedetomidine, ropivacaine, bupivacaine, or study medications. * Second- or third-degree atrioventricular block without a permanent pacemaker. * Resting heart rate \3 months before surgery). * Chronic treatment with α2-adrenergic agonists. * Cognitive impairment or inability to complete postoperative questionnaires. * Infection at the injection site. * Coagulopathy or ongoing anticoagulation precluding neuraxial anesthesia according to current guidelines. * Revision total hip arthroplasty. * Simultaneous bilateral total hip arthroplasty. * Participation in another interventional clinical trial within the previous 30 days.