Evaluating the Effect of Melatonin on Hemodynamic Responses and Anesthesia Depth After Laryngoscopy in Opium-Addicted Patients Undergoing Elective Lumbar Spine Surgery: A Triple-Blinded Randomized Clinical Trial

Background: Melatonin, a hormone known for regulating sleep, may also play a role in managing stress responses during anesthesia. Research suggests that it can reduce the required doses of anesthetics and minimize complications. This is particularly important for patients with μ-opioid receptor addiction, who typically need higher doses and are at increased risk for cardiovascular complications. Therefore, finding ways to lessen these complications in this population is crucial. Objectives: This study aims to investigate the effects of melatonin on hemodynamic responses and Bispectral Index (BIS) in μ-opioid receptor agonist addicted patients undergoing lumbar spine surgery. Methods: A triple-blinded clinical trial was conducted including 100 patients addicted to μ-opioid receptor agonists, who were candidates for lumbar spine surgery. They were randomly assigned to two groups: One group received 6 mg of melatonin, while the other received a placebo. Patients, clinical assessors, and data analysts were all blinded. Hemodynamic parameters and the BIS were recorded at three consecutive time points. Additionally, the amount of consumed propofol was recorded in both groups. The analysis involved using either repeated measures ANOVA or the Friedman test, along with independent t-tests or the Mann-Whitney U test. Results: The study recruited 100 patients (38 females, 62 males) with a mean age of 41.79 ± 13.88 years, divided into two groups of 50 patients each. During the procedure, all hemodynamic variables significantly increased over time in both groups (P-value < 0.05). The independent t-test showed that hemodynamic variables in the melatonin group were lower than in the control group. Conclusions: Premedication with melatonin significantly reduced hemodynamic parameters during induction and intubation in patients addicted to μ-receptor agonists, and those receiving melatonin achieved a deeper level of anesthesia.