Could a quick ketamine infusion lift depression in ICU patients?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

\*\*Inclusion Criteria:\*\* * Age 18 to 99 years. * Male or female. * Admission to an intensive care unit for 6 or more days at the time of screening. * Moderate to severe depressive symptoms, defined as a Patient Health Questionnaire-9 score of 10 or greater at screening. * Ability to provide informed consent. \*\*Exclusion Criteria:\*\* * History of psychosis or hallucinations, as assessed by review of the electronic medical record and patient interview during screening. * History of prolonged QT interval. * History of dementia. * History of major depressive disorder before the current intensive care unit admission. * History of psychiatric diagnosis, including dissociative disorder, primary psychotic disorder, mania with psychosis, pervasive developmental disorder, cognitive disorder, or anorexia nervosa. * Known allergy to ketamine or diphenhydramine. * History of increased intracranial pressure, hypertensive hydrocephalus, or increased intraocular pressure. * Hemodynamic instability at the time of screening, defined as peripheral oxygen saturation \<95%, systolic blood pressure \<90 mmHg or \>180 mmHg, heart rate \<50 or \>120 beats/min, or respiratory rate \<10 or \>30 breaths/min. * Patient refusal to participate or to provide informed consent. * Pregnancy, postpartum period within 2 months, or breastfeeding. * Presence of intracranial mass or vascular lesion. * Altered mental status precluding informed consent. * Body weight \>115 kg or \<45 kg. * Active psychosis. * Current treatment with medications that may interfere with the N-methyl-D-aspartate receptor system, including lamotrigine, acamprosate, memantine, riluzole, or lithium. * Current treatment with aminophylline or theophylline. * Active substance withdrawal or use of hallucinogens, including cannabis, in the past month, as determined by clinical interview and urine drug screening.