This is an open prospective study of a single, low dose (0.5 mg/kg) intravenous (IV) Ketamine in 10 adolescent subjects admitted to Nationwide Childrens Hospital following a serious suicide attempt and who meet criteria for major depression or bipolar disorder I, current episode depressed. Subjects will be recruited via the psychiatry consult service, evaluated on the floor and if eligible and consent is obtained, transferred to the PACU for IV Ketamine infusion. Following infusion and when PACU discharge criteria are met, subjects will be transferred back to their floor for medical and psychiatric monitoring until they can be transferred to an inpatient psychiatric unit for additional care. Subjects will be transferred to an inpatient psychiatric unit for continued psychiatric care as part of their routine psychiatric care via the consult team. The research team will follow-up by telephone one week and four weeks after Ketamine injection to collect additional information about the patient's overall course and response.