Hemodynamic Effects of Bilateral and Unilateral Spinal Anesthesia Using the Continuous Pressure Recording Analytical Method.

This randomized controlled study aims to compare the intraoperative hemodynamic effects of unilateral and bilateral spinal anesthesia in elderly patients undergoing elective total hip arthroplasty. Seventy-four patients aged 65 years and older will be randomized into two groups: unilateral spinal anesthesia (n=37) and bilateral spinal anesthesia (n=37). Hemodynamic parameters including cardiac output, stroke volume, stroke volume variation, pulse pressure variation, and systemic vascular resistance will be continuously monitored using the Pressure Recording Analytical Method (PRAM)-based MostCare monitoring system. Intraoperative fluid requirements and vasopressor consumption will also be evaluated. The study seeks to determine whether unilateral spinal anesthesia provides greater hemodynamic stability and reduces the need for fluid administration and vasopressor support compared with conventional bilateral spinal anesthesia in elderly patients undergoing hip arthroplasty.

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 \1.5 or platelet count \