Intranasal Ketamine in Ultra-REsistant Depression (SURE-ECT Non Responders)

A sterile form of ketamine will be administered intranasally twice weekly for four weeks. Dosing schedule will be determined based on patient's weight using a specialized formula. Patients will be started at the lowest dose during the first treatment session. Dose will be titrated further to therapeutic dose in the following sessions. The dose will be adjusted if patients do not tolerate full therapeutic doses. After receiving the second treatment of each week, participants will be seen by a study physician to determine dosing for the following week. Patients will be monitored by trained personnel for the full duration of the 2 hour supervision period. Vital signs and physical symptoms will be monitored consistently and measurements taken every 30 minutes. Appropriate medications will be provided to manage treatment-related side effects and any adverse events. Labetalol will be used in the management of treatment-related transient hypertension as needed.