Background: Studies conducted in adults undergoing surgery reported a beneficial effect of oral melatonin administered before surgery. There is a paucity of such data in children undergoing anesthesia and surgery.
Methods: Children undergoing surgery were randomly assigned to receive preoperatively oral midazolam 0.5 mg/kg or oral melatonin 0.05 mg/kg, 0.2 mg/kg, or 0.4 mg/kg. The primary outcome of the study was preoperative anxiety (Yale Preoperative Anxiety Scale). The secondary outcomes were the children's compliance with induction (Induction Compliance Checklist), emergence behavior (Keegan scale), and parental anxiety (State-Trait Anxiety Inventory).
Results: Repeated measures ANOVA showed that children who received melatonin at any of the three doses were more anxious compared with children who received midazolam (P < 0.001). Parental anxiety did not differ on the basis of the experimental condition (P = ns). The melatonin groups showed a dose-response effect on emergence behavior. Children who received melatonin developed less emergence delirium compared with those who received midazolam (P < 0.05), and the effect was dose related; the incidence after 0.05 mg/kg melatonin was 25.0%, incidence after 0.2 mg/kg melatonin was 8.3%, and incidence after 0.4 mg/kg melatonin was 5.4%.
Conclusions: Midazolam is more effective than melatonin in reducing children's anxiety at induction of anesthesia. Melatonin showed a direct dose-dependent effect on emergence delirium.