Intrathecal Dexmedetomidine and Postoperative Delirium in Elderly Hip Fracture Surgery

Postoperative delirium (POD) is a common and serious complication in elderly patients undergoing surgical repair for hip fractures, often triggered by acute pain, surgical stress, neuroinflammation, and opioid consumption. Although spinal anesthesia using bupivacaine is commonly performed, local anesthetics alone often require additional systemic rescue opioids for postoperative pain relief, which can further increase delirium risk. Dexmedetomidine is a selective alpha-2 adrenergic agonist that has demonstrated neuroprotective, anti-inflammatory, and opioid-sparing effects. The purpose of this clinical trial is to evaluate whether adding intrathecal dexmedetomidine as an adjuvant to hyperbaric bupivacaine during spinal anesthesia reduces the incidence and severity of postoperative delirium compared to hyperbaric bupivacaine alone in geriatric patients undergoing hip fracture surgeries. Participants will be randomly assigned to one of two groups: * Dexmedetomidine Group: Receives hyperbaric bupivacaine 0.5% (10 mg) combined with 5 µg dexmedetomidine intrathecally. * Control Group: Receives hyperbaric bupivacaine 0.5% (10 mg) combined with normal saline intrathecally. The primary outcome is the incidence of postoperative delirium evaluated using the Confusion Assessment Method (CAM) twice daily during the first 48 hours following surgery. Secondary assessments include the duration and severity of delirium episodes, spinal block characteristics, hemodynamic stability, postoperative pain scores, rescue analgesic consumption, sedation levels, adverse events, and total hospital length of stay.

Inclusion Criteria: * Elderly patients aged 65 years or older. * American Society of Anesthesiologists (ASA) physical status I, II, or III. * Patients scheduled for elective or emergency hip fracture surgeries (e.g., internal fixation, hemiarthroplasty, or total hip arthroplasty). * Eligible for and scheduled to undergo the procedure under spinal anesthesia. * Written informed consent provided by the patient or their legally authorized representative. Exclusion Criteria: * Patient or legal representative refusal to participate in the study or receive spinal anesthesia. * Absolute contraindications to spinal anesthesia (e.g., coagulopathy, bleeding disorders, localized infection at the puncture site, or severe hypovolemia). * Pre-existing cognitive or neurological impairment (diagnosed dementia, baseline Mini-Mental State Examination \[MMSE\] score \< 24, history of recent stroke, severe psychiatric illness, or chronic use of sedatives/antidepressants). * Cardiovascular contraindications (baseline bradycardia with heart rate \< 50 beats/min, advanced second- or third-degree atrioventricular block, or severe baseline hypotension with mean arterial pressure \< 65 mmHg). * Severe end-stage organ failure (severe hepatic or renal impairment). * Severe auditory or visual impairment hindering proper cognitive evaluation, or inability to communicate. * Intraoperative failure of spinal anesthesia requiring conversion to general anesthesia, surgical duration exceeding 2 hours, or massive intraoperative blood loss/hemodynamic instability.