Ketamine Augmentation of Electroconvulsive Therapy: A Scoping Review of Dose-Dependent Effects in Major Depressive Disorder

Intravenous ketamine infusions in subanesthetic doses have been shown to rapidly alleviate depressive symptoms. However, the efficacy of ketamine as an anesthetic during electroconvulsive therapy (ECT) for major depression has not yet been answered by a large randomized control trial (RCT). This scoping review aims to examine the available literature to determine whether the dose of ketamine used during ECT influences the response to treatment. A literature search was conducted on PubMed to identify all published RCTs within the last 10 years which compared ketamine anesthesia during ECT for major depression with another anesthetic. Studies using low (<0.8 mg/kg) versus high (≥0.8 mg/kg) doses of ketamine during ECT were evaluated for the differences in outcomes using depression rating scales. Studies that examined ketamine as a standalone treatment for depression or focused primarily on the anesthetic benefits of ketamine were excluded from our review. Fifteen studies were utilized for this literature review. Overall, the studies showed inconsistent results in terms of the speed and magnitude of response to ketamine-assisted ECT in patients with major depression. Limitations of the available literature are discussed, including the lack of head-to-head comparisons, differences in methodology, inclusion/exclusion criteria, and primary and secondary endpoints.