Ketamine & Crisis Response Plan for Suicidal Ideation in the ED

The goal of this randomized pilot trial is to assess the feasibility of administering a combination of 100mg intramuscular (IM) ketamine and Crisis Response Plan (a short psychosocial intervention) for patients with acute suicidality in the context of the Emergency Department setting. This study will assess a combination of a pharmacologic intervention and a psychosocial one. The pharmacologic intervention is a one-time dose of 100mg ketamine delivered intramuscularly (IM) while the patient is in the ED. The psychosocial intervention under study is a brief, patient-centered therapy which takes, on average, 30 minutes to administer. Both interventions will be administered only once. The main questions this study aims to answer are: * Determine if 100mg of IM ketamine and Crisis Response Plan in combination results in greater short-term reductions in suicidal ideation in adult patients who report acutely elevated suicide risk during an ED visit. * Examine potential weight-based dose response differences in the reductions in suicidal ideation to determine if future treatment protocols with IM ketamine may benefit from weight-based dosing.