Ketamine and melatonin for the prevention of postoperative delirium in patients with colorectal cancer: a feasibility study.

Purpose: This study aimed to examine the feasibility and effects of preoperative 5 mg of melatonin and intraoperative 50 mg of ketamine on postoperative delirium (POD) prevention in candidates for colorectal cancer surgery.

Methods: In this randomized controlled trial, adults (> 18 years) who were candidates for elective colorectal cancer surgery were included in the study. Patients were randomized into four groups: placebo/saline (PS), melatonin/saline (MS), placebo/ketamine (PK), and melatonin/ketamine (MK). The groups received either 5 mg of oral melatonin or a placebo the night before surgery and 50 mg of ketamine or normal saline after anesthesia induction. The occurrence and severity of POD and pain severity were assessed via the confusion assessment method for the intensive care unit (CAM-ICU) and visual analogue scale (VAS), respectively (twice daily), until postoperative day 4.

Results: One-hundred and four patients (51% male, mean age: 56.29 ± 12.65) with a rate of 4.7 patients per week were recruited, with an attrition rate of 13.3%. The prevalence of POD was 17.3%, 22.23%, 16.67%, and 16.67% in the PS group, the MS group, the MK group, and the PK group, respectively. Compared with the control, none of the interventions significantly reduced the likelihood of POD occurrence.

Conclusion: This randomized controlled trial demonstrated the feasibility of recruiting and retaining surgical patients for a multi-arm perioperative intervention study. Although the interventions did not significantly reduce the incidence of POD, the study design and procedures were feasible, with acceptable recruitment and attrition rates. Compared to placebo, none of the interventions significantly reduced the incidence of POD; however, time was a significant factor, with POD incidence, severity, and pain decreasing longitudinally.

Trial regsitration: IR.TUMS.IKHC.REC.1401.374, registration date: 14 February 2023 and IRCT code: IRCT20120527009886N2, registration date: 07/03/2023.