 After loss of consciousness, a tetanic stimuli will be applied using the peripheral nerve stimulator and repeated every thirty seconds. The propofol infusion will continue to be increased every one minutes by 0.2mcgml. Loss of response to painful stimuli will be defined as the point at which the patient fails to make a withdrawal motion from the tetanic stimulation. Here, heart rate, blood pressure BIS number and propofol effect site concentration will be recorded. 