Ketamine For Suicidal Ideation

Inclusion Criteria: * English speaking Male or female patients, 18-80 years * Patients have voluntarily admitted themselves to an inpatient psychiatric unit at MSH or, regarding the outpatient population, have clinically significant suicidal ideation without intent to harm themselves * Women of childbearing potential must have a negative pregnancy test * Clinically significant suicidal ideation and score of ≥4 on MADRS item 10 for suicidality * Each subject must have a level of understanding sufficient to agree to all tests and examinations required by the protocol and must sign an informed consent document Exclusion Criteria: * Lifetime history of schizophrenia or other primary psychotic disorder * Current presence of psychotic symptoms * Lifetime history of a clearly established psychotic episode * Established diagnosis of Schizoid, Schizotypal or Paranoid personality disorder * Urine toxicology screen positive for drugs of abuse on admission * Substance abuse or dependence within the preceding 1 month * Anticipated discharge within 7 days of study enrollment (for patients in the inpatient arm) * Women who plan to become pregnant, are pregnant or are breast-feeding * Concurrent course of electroconvulsive therapy (ECT) * Any unstable medical illness including hepatic, renal, gastro-enterologic, respiratory, cardiovascular, endocrinologic, neurologic, immunologic, or hematologic disease * Clinically significant abnormal findings of laboratory parameters, physical examination, or ECG * The presence of any known or suspected contraindications to midazolam or ketamine including, but not limited to, known allergic reactions to these agents or acute intermittent porphyria * Uncontrolled hypertension, defined as BP systolic \>160 or BP diastolic \>100 on medications * Arrhythmia requiring medication * Severe coronary artery disease, defined as Canadian Cardiovascular Status III or IV