Clinical Research Directory

Inclusion Criteria: 1. Adults aged 65 years and older. 2. Patients scheduled for elective total hip arthroplasty. 3. Patients with an American Society of Anesthesiologists (ASA) physical status classification of II, III, or IV. 4. Patients with a Glasgow Coma Scale (GCS) score of 13-15 who are conscious and able to cooperate. 5. Patients with suitable peripheral arterial anatomy for PRAM monitoring. 6. Patients who provide written informed consent to participate in the study. 7. Patients without any clinical contraindication to spinal anesthesia. - Exclusion Criteria: 1. Glasgow Coma Scale (GCS) score \<13. 2. Age below 65 years. 3. History of previous major neurosurgical intervention. 4. Anatomical abnormality, vascular defect, or infection at the site intended for arterial catheter placement for PRAM monitoring. 5. Severe spinal deformity (e.g., severe scoliosis, previous spinal fusion surgery, or spinal trauma). 6. Current anticoagulant therapy or coagulopathy (INR \>1.5 or platelet count \<75,000/mm³). 7. Presence of skin infection or systemic infection/sepsis. 8. Severe hypovolemia or decompensated cardiac disease in which spinal anesthesia is contraindicated. 9. Known allergy or hypersensitivity to local anesthetics or sedative agents. 10. Local infection or wound at the planned spinal puncture site. 11. Clinical contraindication to spinal anesthesia (e.g., increased intracranial pressure, septicemia, or severe hypotension). -