Study aim: Comparision the effect of adjuvant Reminfentanil, Dexmedetomidine or metoral with thiopental on hemodynamic status in patients with major depressive disorder candidates for electroconvulsive therapy Design: The study will be double blind and clinical trial.90 patients will be randomly divided into 3 groups. The groups are parallel. The trial phase is 3. Settings and conduct: patients with major depressive disorder candidates for electroconvulsive therapy in Amirkabir Hospital in Arak are divided into 3 groups by simple randomization with blocks.The study is double-blind in which outcome evaluator and data analyst and participant are kept blind. Participants/Inclusion and exclusion criteria: Inclusion criteria:All patients with major depressive disorder are candidates for ETC ,consent to participate in the study, 18 to 60 years,body mass index 20 to 30, , no history of underlying heart, lung, kidney and liver diseases, no history of recent CVA or MI, insensitivity to drugs Exclusion criteria:all patients who experience cardiorespiratory arrest during ECT, all patients who need intubation after ECT due to prolonged apnea and respiratory failure, all patients who do not experience sufficient and desired seizures during ECT, all patients who want to withdraw from the study or do not want to continue electroshock therapy Intervention groups: Intervention group1: Before induction of anesthesia, 100 micrograms of Remifentanil is injected intravenously. Intervention group 2: Before the induction of anesthesia, intravenous injection of 0.5 mg/kg Dexmethomidine is performed. Intervention group 3: After induction of anesthesia as mentioned above, immediately before stimulation with ECT, an amount of 2.5 mg Metoral is injected . Main outcome variables: Average blood pressure, average heart rate, average percentage of oxygen saturation, patient satisfaction, agitation, seizure duration, recovery period