Comparison of Hemodynamic Effects of Hypobaric and Hyperbaric Bupivacaine in Spinal Anesthesia in Geriatric Patients

Patients will be randomly assigned to one of two groups: HypoB (% 0.5 bupivacaine 3cc+ 2cc distilled water) or HyperB (% 0.5 bupivacaine 3cc+ 2cc %10 dextrose). For pre-positioning analgesia, an intravenous dose of fentanyl at 0.5 mcg/kg will be administered. Patients will then be positioned in the appropriate lateral decubitus position based on whether hypobaric or hyperbaric bupivacaine is used. Spinal anesthesia will be performed using 3 cc local anesthetic solution, followed by 15 minutes of lateralization.

During the surgery, hemodynamic parameters, sensory block levels at the 5th, 10th, 15th, and 20th minutes at lateral and supine position, and motor block levels with bromage scale at the 15th and 20th minutes at supine position will be recorded. The spread of the block to the T8 dermatome level was considered an indicator of a successful block. Hemodynamic parameters (blood pressure, heart rate, peripheral oxygen saturation) will be recorded at 0, 5, 10, 15, 20, 30, 40, 50, 60, 90, and 120 minutes intraoperatively. Patients will receive crystalloid infusion at a rate of 5-7 ml/kg per hour throughout the procedure. The volume of intraoperative bleeding, the amount of blood products administered, and the doses of ephedrine, atropine, and noradrenaline used will also be documented. If the heart rate falls below 45 beats per minute, 0.5 mg of intravenous atropine will be administered.

A decrease in blood pressure of 20% or more from baseline will be defined as hypotension. In such cases, ephedrine will be administered. If hypotension persists despite a total dose of 20 mg ephedrine, a noradrenaline infusion will be initiated.