The Effect of Pregabalin Given Preoperatively on the Tourniquet Induced Ischemia-reperfusion

Investigators will randomize patients into two groups. 1) Pregabalin group 2) Control group. Investigators will give orally pregabalin 150 mg to the pregabalin group patients two times (first dose 1 day before surgery., second dose 1 hour before surgery). On the other hand placebo drug will give to the control group at the same times. Investigators will perform combined spinal epidural anesthesia for surgery and inject 3 cc 0.5% hyperbaric bupivacaine to subarachnoid space. Investigators will take blood samples for measurement of ischemia-reperfusion determinants, immediately before surgery, shortly before tourniquet deflation, and 20 minutes after tourniquet deflation. Then these samples will be analysed by ELISA method.