Table 1.

Study inclusion and exclusion criteria.

CRITERION		METHOD OF ASCERTAINMENT
Inclusion	1. 18–65 years old	Interview
	2. DSM51 unipolar or bipolar (I, II, or Unspecified) major depressive episode	MINI2 diagnostic interview
	3. Assessed by psychiatric ED staff as needing inpatient treatment due to suicide risk	ED clinical assessment
	4. Subject agrees to voluntary inpatient admission	Interview
	5. Beck Scale for Suicidal Ideation (SSI) score of 4 or higher	SSI scale
	6. Subjects 60–65 years old must score 25 or higher on the Mini Mental Status Exam (MMSE) at screening	MMSE
Exclusion	1. Co-occurring substance excluded if: acute intoxication or withdrawal; more than rare recreational use of opioids/ ketamine/PCP (e.g. >once in past year); needs specialized addiction treatment/detox and cannot be handled on study units; primary alcohol/substance disorder with secondary depression	Assessed case by case in collaboration with ED team based on labs, clinical assessment, and study screening
	2. Current psychosis or mania	Clinical and MINI2 assessments
	3. Intellectual disability	Clinical assessment
	4. Inadequate understanding of English and/or lack of capacity for informed consent.	Clinical assessment
	5. Pregnancy or lactation	Urine or blood pregnancy test
	6. Any medical contraindication to ketamine or midazolam; Total current dose of lorazepam or benzodiazepine equivalent greater than 3 mg daily is excluded.	Medical history
	7. Unstable medical or neurological illness such as uncontrolled hypertension, significant cardiac arrhythmia, unstable cerebrovascular disease. Chronic, stable medical conditions such as controlled hypertension or diabetes are not excluded.	Medical history, labs, and ECG

¹DSM5 = Diagnostic and Statistical Manual of Mental Disorders Fifth Edition.

²MINI = Mini International Neuropsychiatric Interview.