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Background: Postoperative depressive symptoms are associated with pain, readmissions, death, and other undesirable outcomes. Ketamine produces rapid but transient antidepressant effects in the perioperative setting. Longer infusions confer lasting antidepressant activity in patients with treatment-resistant depression, but it is unknown whether a similar approach may produce a lasting antidepressant effect after surgery. This protocol describes a pilot study that will assess the feasibility of conducting a larger scale randomized clinical trial addressing this knowledge gap. Methods: This single-center, double-blind, placebo-controlled pilot trial involves the enrollment of 32 patients aged 18 years or older with a history of depression scheduled for surgery with planned intensive care unit admission. On the first day following surgery and extubation, participants will be randomized to an intravenous eight-hour infusion of either ketamine (0.5 mg kg -1 over 10 minutes followed by a continuous rate of 0.3 mg kg -1 h -1) or an equal volume of normal saline. Depressive symptoms will be quantified using the Montgomery-Asberg Depression Rating Scale preoperatively and serially up to 14 days after the infusion. To detect ketamine-induced changes on overnight sleep architecture, a wireless headband will be used to record electroencephalograms preoperatively, during the study infusion, and after infusion. The primary feasibility endpoints will include the fraction of patients approached who enroll, the fraction of randomized patients who complete the study infusion, and the fraction of randomized patients who complete outcome data collection. Conclusions: This pilot study will evaluate the feasibility of a future large comparative effectiveness trial of ketamine to reduce depressive symptoms in postsurgical patients. Registration: K-PASS is registered on ClinicalTrials.gov: NCT05233566; registered February 10, 2022.

Background: Surgical patients with previous depression frequently experience postoperative depressive symptoms. This study's objective was to determine the feasibility of a placebo-controlled trial testing the impact of a sustained ketamine infusion on postoperative depressive symptoms. Methods: This single-centre, triple-blind, placebo-controlled randomised clinical trial included adult patients with depression scheduled for inpatient surgery. After surgery, patients were randomly allocated to receive ketamine (0.5 mg kg−1 over 10 min followed by 0.3 mg kg−1 h−1 for 3 h) or an equal volume of normal saline. Depressive symptoms were measured using the Montgomery–Asberg Depression Rating Scale. On post-infusion day 1, participants guessed which intervention they received. Feasibility endpoints included the fraction of patients approached who were randomised, the fraction of randomised patients who completed the study infusion, and the fraction of scheduled depression assessments that were completed. Results: In total, 32 patients were allocated a treatment, including 31/101 patients approached after a protocol change (31%, 1.5 patients per week). The study infusion was completed without interruption in 30/32 patients (94%). In each group, 7/16 participants correctly guessed which intervention they received. Depression assessments were completed at 170/192 scheduled time points (89%). Between baseline and post-infusion day 4 (pre-specified time point of interest), median depressive symptoms decreased in both groups, with difference-in-differences of −1.00 point (95% confidence interval −3.23 to 1.73) with ketamine compared with placebo. However, the between-group difference did not persist at other time points. Conclusions: Patient recruitment, medication administration, and clinical outcome measurement appear to be highly feasible, with blinding maintained. A fully powered trial may be warranted. Clinical trial registration: NCT05233566.

Background: Postoperative depressive symptoms are associated with pain, readmissions, death, and other undesirable outcomes. Ketamine produces rapid but transient antidepressant effects in the perioperative setting. Longer infusions confer lasting antidepressant activity in patients with treatment-resistant depression, but it is unknown whether a similar approach may produce a lasting antidepressant effect after surgery. This protocol describes a pilot study that will assess the feasibility of conducting a larger scale randomized clinical trial addressing this knowledge gap. Methods: This single-center, double-blind, placebo-controlled pilot trial involves the enrollment of 32 patients aged 18 years or older with a history of depression scheduled for surgery with planned intensive care unit admission. On the first day following surgery and extubation, participants will be randomized to an intravenous eight-hour infusion of either ketamine (0.5 mg kg-1 over 10 minutes followed by a continuous rate of 0.3 mg kg-1 h-1) or an equal volume of normal saline. Depressive symptoms will be quantified using the Montgomery-Asberg Depression Rating Scale preoperatively and serially up to 14 days after the infusion. To detect ketamine-induced changes on overnight sleep architecture, a wireless headband will be used to record electroencephalograms preoperatively, during the study infusion, and after infusion. The primary feasibility endpoints will include the fraction of patients approached who enroll, the fraction of randomized patients who complete the study infusion, and the fraction of randomized patients who complete outcome data collection. Conclusions: This pilot study will evaluate the feasibility of a future large comparative effectiveness trial of ketamine to reduce depressive symptoms in postsurgical patients. Registration: K-PASS is registered on ClinicalTrials.gov: NCT05233566; registered February 10, 2022.