This study will explore whether the use of a medication, Ketamine, can help patients who come to the ER with thoughts of suicide by improving their mood and reducing thoughts of suicide. Ketamine has been used for this purpose in patients who have been hospitalized, but it has not been well studied in the ER. The investigators are first trying to show that patients and doctors in the ER find the treatment acceptable. The investigators also hope to determine whether Ketamine is effective in decreasing the severity of patient's suicidal thinking while in the ER. If this treatment works, future studies will look at whether it can help patients be discharged from the hospital earlier.

Research Procedures: Patients will be enrolled into the study on a voluntary basis after the research assistant has fully explained all the risks and benefits of the study (informed consent). Research assistants, Emergency Department staff, and the Psychiatry team will help identify patients for the study. Patients will be asked to complete surveys measuring the degree of their suicidal thinking and mood. Additional information will be collected on patients such as their demographics, current medications, and medical problems. Patients in the study will receive the medication, Ketamine, which will be given through an intravenous catheter (IV) at a dose based on the patient's weight and slowly infused over 40 minutes. Patients will be monitored during their stay in the Emergency Department by Emergency Department physicians and nurses for any signs of side effects to the medication. Patients will be asked to complete several surveys at specific time periods after the administration of Ketamine. All patients in the study will receive usual psychiatric care in addition to the study medication.

Mood disorders complicated by suicidal ideation (SI) are common among patients presenting to the Emergency Department (ED). Under current standard practice, patients awaiting psychiatric evaluation in the emergency department do not typically receive interventions to address their mood disorder or SI. With no end to the extended ED boarding of psychiatric patients in sight, improvements in the acute treatment of SI with ketamine may help more patients receive prompt and appropriate treatment. Low-dose ketamine has been well studied in psychiatric literature. Studies involving a single dose of ketamine are promising, demonstrating both immediate and sustained reductions in suicidal ideations. Low dose ketamine has been well-studied in the ED for pain, asthma, and agitation, but not mood disorders or SI.

This study aims to determine whether or not it is feasible to administer low dose ketamine in the emergency department for the management of mood disorders with SI. Feasibility of ketamine administration in the ED and will be determined by: (1) ability to recruit participants, (2) tolerability of the intervention, and (3) acceptability by patients/providers. The investigators will also explore whether the administration of ketamine results in improvements in mood and SI.

This prospective open label feasibility pilot study will enroll 20 participants to receive ketamine at 0.5mg/kg infused intravenously over 40 minutes. Patients that have active suicidal ideation as determined by psychiatry staff who are being admitted to psychiatry under voluntary certification will be eligible for the study. The investigators will assess self-reported mood and suicidal ideations pre- and post-infusion of ketamine. Participants will complete assessments at baseline (pre-infusion), 2 hours and 6 hours post-infusion, and daily while in the ED until inpatient disposition.

The investigators hypothesize ketamine administration will be feasible in the emergency department and will result in improved mood and decreased SI.

Inclusion Criteria:

• English speaking
• between 18 and 65 years of age
• have active suicidal ideation as determined by psychiatry staff
• are being admitted to psychiatry under voluntary certification and are able to provide informed consent.

Exclusion Criteria:

• have been previously enrolled in the trial
• are pregnant or breastfeeding; have a known or suspected allergy to ketamine; have used ketamine within 24h of presentation
• require antipsychotics (prescription or PRN by ED staff) or ED administration of other mood-altering medications for the management of acute agitation
• have known renal or liver failure; have neurologic, respiratory, or hemodynamic compromise as determined by the treating ED physician
• have history of stroke or cardiac disease (prior MI, cardiac stents or bypass surgery); or are incarcerated