Ketamine for Acute Suicidal Ideation in the Emergency Department: Randomized Controlled Trial

Inclusion Criteria:

* Patients age 18 to less than 75 who present to the SAMMC ED with either overt or incidental suicidal ideations with a SADPERSONS score 5 or greater that the treating provider feels warrant formal evaluation.

Exclusion Criteria:

* -Poor vital sign stability hypoxia: O2 \< 95%, hypotension: SBP\< 90 hypertension: SBP\>180 Heart rate: \< 50 or \>120 Respiratory Rate: \<10 or \>30
* Altered mental status or intoxication
* Patient is unwilling to participate or provide informed consent
* Any allergy to ketamine or diphenhydramine
* Patient is female of child-bearing age and unwilling to provide urine or blood for HCG analysis
* Pregnancy or breast feeding
* Presence of chronic oxygen-dependent pulmonary disease, liver cirrhosis, or renal disease requiring dialysis
* Presence of ischemic heart disease, heart failure, or a history of unstable dysrhythmias
* Presence of intracranial mass or vascular lesion.
* Presence of a history of psychosis or hallucinations (as assessed by electronic chart review)
* Weight greater than 115 kg or less than 45kg
* History of increased intracranial pressure/hypertensive hydrocephalus
* Non-English speaking patients
* Patient is acutely psychotic
* Provider feels that patient currently or likely will require chemical and/or physical restraints
* History of prolonged QT-interval