A feasibility study of low-dose ketamine for acute management of suicidal ideation

L. and colleagues conducted a single-arm, open-label feasibility pilot in an emergency department (ED) setting. The study enrolled 14 participants presenting to the ED with acute suicidal ideation (SI) who were awaiting voluntary admission to inpatient psychiatry. Each participant received an intravenous infusion of ketamine at 0.5 mg/kg. Feasibility was defined primarily by acceptability of ketamine to participants and treating physicians, together with tolerability (for example adverse events and any infusion discontinuations) and the practical ability to recruit eligible patients in the ED. The trial’s primary efficacy endpoints were within-subject changes in self-reported mood and suicidal ideation from baseline (pre-infusion) to 2 hours post-infusion. Mood was measured with the Immediate Mood Scaler (IMS) and suicidality with the Columbia Suicide Severity Rating Scale (C-SSRS). Ketamine-related side effects and dissociative symptoms were measured with the Side Effect Rating Scale for Dissociative Anesthetics (SERSDA). Assessments were performed at baseline, 2 hours and 6 hours after infusion, and then daily while patients remained in the ED until inpatient disposition. Assessments were administered both by research assistants and self-report, and data were collected in REDCap. The extracted text does not clearly report further details of statistical analysis methods (for example models or handling of missing data).

The study enrolled 14 participants. At baseline all participants reported severe depression and active suicidal ideation. No serious adverse events were reported. Acceptability of the ketamine intervention was rated highly by both participants and physicians (reported as >70%). On the primary efficacy measures, two hours after receiving ketamine 0.5 mg/kg the mean suicidal ideation score and mean somatic symptom burden were reduced compared with baseline (reported P < 0.001 and P = 0.005, respectively), and mean self-reported mood increased (P = 0.006). The authors report that improvements in mood and reductions in suicidality persisted at 6 hours post-infusion. Reported side effects and physical symptoms measured by SERSDA decreased after receiving ketamine compared with baseline. Treatment response was heterogeneous: roughly half of participants experienced marked improvements in mood and suicidality, while the remainder remained relatively stable over the observation period. The extracted text notes one participant died by suicide two months after participation; this event was determined by the authors to be unrelated to the ketamine intervention. The Results section indicates that assessments were completed using REDCap and that feasibility and efficacy were the trial’s two primary endpoints.

The authors interpret the findings as supporting the feasibility, tolerability and short-term efficacy of low-dose ketamine (0.5 mg/kg IV) for acute management of suicidal ideation in the ED. They state that ketamine was acceptable to both patients and physicians, produced rapid improvements in mood and reductions in suicidality within 2 hours that were sustained to 6 hours, and was not associated with serious adverse events in this small sample. L. and colleagues position these results as adding to a growing body of evidence that ketamine can be administered in ED settings for crisis stabilisation, while emphasising that ketamine should not be regarded as a curative intervention in the ED but rather as a bridging therapy to connect patients to longer-term care (for example psychotherapy and antidepressant medications). The authors suggest a possible explanation for the observed reduction in somatic symptoms is that somatic burden at baseline was driven by mood disturbance and SI and thus improved as mood improved. Key limitations acknowledged by the authors include the small, open-label single-arm design and heterogeneity of treatment response across participants. They note the need to further evaluate whether particular subgroups derive larger benefits and to establish longer-term safety and effectiveness through larger studies. The authors also highlight the one-post study suicide as a reminder that participants were a high-risk group and that long-term follow-up is important, although they report this death was judged unrelated to study treatment. Future research priorities they state are larger controlled trials to confirm safety and efficacy and investigations into heterogeneity of treatment effect and longer-term outcomes.

The authors conclude that low-dose ketamine (0.5 mg/kg IV) administered in the ED was feasible, well tolerated and showed promising short-term efficacy for reducing suicidal ideation and improving mood. They recommend viewing ketamine as a bridging intervention to support connection to definitive, longer-term psychiatric care rather than as a curative treatment, and call for larger studies to further establish safety, effectiveness and which patients are most likely to benefit.