Twenty-five patients will be a total of 150 ECT treatments in this prospective, double-blinded, crossover study. Each patient will receive either 0.2 mg/kg etomidate (Group 1) or 8% sevoflurane (Group 2) in 100% oxygen at 6 L/min fresh gas flow until loss of consciousness for their initial electroconvulsive therapy session. In subsequent sessions, patients will receive the alternative sevoflurane concentration and then alternated between doses until the sixth session. Muscle paralysis will achieve with 1 mg/kg succinylcholine. Motor (EMG) and electroencephalography seizure duration (EEG), heart rate (HR) and mean arterial pressure (MAP) values, and recovery times will recorde.