Objective: Ketamine in electroconvulsive therapy (ECT) anesthesia has been reported to be associated with better seizure quality and longer duration compared with methohexital anesthesia. Furthermore, ketamine may enhance the efficacy of ECT while having rapid independent antidepressant properties itself. However, data on the effects of ketamine with ECT are inconsistent, and there are no reports of S-ketamine. The aim of the present pilot study was to explore the effects of S-ketamine as an adjuvant to propofol on the efficacy, seizure duration, and quality of electroencephalography in patients with treatment-resistant depression.

Methods: Thirty-two patients with a recurrent severe or psychotic major depressive disorder with treatment resistance to antidepressants were included in the study. For induction of anesthesia, the patients were randomized into 2 study groups. The S-ketamine group first received S-ketamine (0.4 mg/kg) as a bolus and then propofol. The treatment-as-usual group first received saline and then propofol.

Results: A statistically significant and clinically relevant reduction in the depression symptom scores was found in both study groups during ECT. There was no difference in the magnitude or speed of response between the study groups, nor was there any difference in the numbers of ECT treatments, seizure thresholds, seizure durations, and the electrical doses either. The patients recovered from anesthesia equally, but the degree of posttreatment disorientation and restlessness was more marked in the S-ketamine group.

Conclusions: In conclusion, a subanesthetic adjuvant dose of S-ketamine with propofol may not increase the effects of ECT in patients with treatment-resistant depression. However, S-ketamine was associated with increased posttreatment disorientation and restlessness.