Comparison of Low-Dose Versus Standard-Dose Hyperbaric Bupivacaine in Spinal Anesthesia

The goal of this randomized controlled trial is to determine whether low-dose hyperbaric bupivacaine provides better hemodynamic stability and postoperative recovery compared with standard-dose hyperbaric bupivacaine in elderly patients undergoing lower limb orthopedic surgery under spinal anesthesia. The main questions it aims to answer are: * Does low-dose hyperbaric bupivacaine reduce the incidence of intraoperative hypotension and bradycardia compared with standard-dose hyperbaric bupivacaine? * Does low-dose hyperbaric bupivacaine improve postoperative recovery profile compared with standard-dose hyperbaric bupivacaine? Researchers will compare elderly patients receiving low-dose hyperbaric bupivacaine with those receiving standard-dose hyperbaric bupivacaine to determine whether a lower intrathecal dose improves cardiovascular stability and recovery without compromising the effectiveness of spinal anesthesia. Participants will: * Provide written informed consent before enrollment. * Undergo elective lower limb orthopedic surgery under spinal anesthesia. * Be randomly assigned to receive either low-dose or standard-dose hyperbaric bupivacaine. * Have their blood pressure, heart rate, and other vital signs monitored throughout the surgical procedure. * Be assessed for intraoperative hypotension and bradycardia according to predefined study criteria. * Be evaluated for postoperative recovery parameters, including motor recovery and readiness for postoperative recovery and mobilization. The information obtained from this study may help identify a safer and more effective spinal anesthetic technique for elderly patients undergoing orthopedic surgery.

Inclusion Criteria: * Male or female patients aged 65 years and above. * Patients scheduled for elective lower limb orthopedic surgery under spinal anesthesia. * American Society of Anesthesiologists (ASA) physical status I-III. * Patients willing to participate and provide written informed consent. Exclusion Criteria: * Refusal to participate in the study. * Contraindications to spinal anesthesia (e.g., infection at puncture site, coagulopathy, severe hypovolemia, raised intracranial pressure). * Known hypersensitivity or allergy to bupivacaine. * Severe valvular heart disease. * Significant cardiac arrhythmias. * Uncontrolled hypertension. * Severe hepatic or renal impairment. * Pre-existing neurological disorders affecting lower limb motor or sensory function. * Severe spinal deformity or previous lumbar spine surgery interfering with spinal anesthesia. * Cognitive impairment or inability to provide informed consent. * Emergency orthopedic procedures.