Nebulized Ketamine for Major Depressive Disorder

Inclusion Criteria: * All individuals 18 years and older with a Montgomery-Asberg Depression Rating Scale score (MADRS) ≥ 20 * Must have a diagnosis of moderate to severe Major Depressive Disorder (MDD) * Structured Clinical Interview for DSM-5 (SCID-5) will be performed to confirm MDD diagnosis Exclusion Criteria: * Adult patients with an allergy to Ketamine * Adult patients with an allergy to Midazolam * Individuals with a history of mania/hypomania or diagnosis of bipolar disorder * Patients on lithium and/or lamotrigine therapy * Recent or current homicidal ideation with an intent to act * MDD with psychotic features or current or past diagnosis of a psychotic disorder * No substance use disorder in the preceding 3 months except nicotine or caffeine or a positive urine screen for substances (except cannabis) * Diagnosis of obsessive-compulsive disorder, antisocial personality disorder, borderline personality disorder, posttraumatic stress disorder, intellectual disability, altered mental status, pregnant or breastfeeding patients, * Patients on \> 2 medications for hypertension * Patients with uncontrolled hypertension (BP \>140 mm Hg systolic and/or \>90 mm Hg diastolic on two separate readings at the time of screening) * Body weight of \> 150kg * Patients with history of congestive cardiac failure * Day of presentation, patients with unstable vital signs (systolic blood pressure \<90 or\>160 mm Hg, pulse rate \<50 or \>150 beats/min, and respiration rate \<10 or \>30 breaths/min) * Consumption of opioids within 24 hours of drug administration * Acutely intoxicated patients will also be excluded