Patients enrolled in the study are randomly allocated by computer-generated random numbers to receive either sevoflurane or ketamine for their initial ECT session. They subsequently receive an alternative study drug in their next session, continuing to alternate between drugs at each session until the sixth session. In group S, sevoflurane are initiated at %8 sevoflurane for anesthesia induction and maintained at 2% to %4 until the electrical stimulus is delivered, In group K, ketamine are given to 1mg/kg ıv bolus.