Pediatric premedication: a double-blind randomized trial of dexmedetomidine or ketamine alone versus a combination of dexmedetomidine and ketamine

Background: Preoperative anxiety is common in pediatric patients. When dexmedetomidine is used alone for sedation as premedication, children tend to awaken when separated from their parents, and body movements occur during invasive procedures. We tested the hypothesis that the combination of dexmedetomidine and ketamine may be a useful premedication to alleviate preoperative anxiety and improve cooperation during intravenous cannulation in pediatric patients, while producing minimal adverse events. Methods: A total of 135 children, aged 2-5 years and American Society of Anesthesiologists status I-II, scheduled for eye surgery were randomly allocated to receive intranasal dexmedetomidine 2.5 mu g/kg (group D), oral ketamine 3 mg/kg and intranasal dexmedetomidine 2 mu g/kg (group DK), or oral ketamine 6 mg/kg (group K) 30 min before surgery. Sedation state was evaluated every 10 min after premedication and emotional state was assessed during separation from their parents and peripheral intravenous cannulation. Adverse events were recorded for 24 h postoperatively. The primary endpoint was the rate of successful intravenous cannulation. Results: The rate of successful venous cannulation was 47% with dexmedetomidine alone, 68% with ketamine alone, and 80% with combined premedication (P = 0.006). The rate of satisfactory separation from parents was not different among groups. The incidence of adverse events was higher in group K compared with the other two groups (postoperative vomiting, P = 0.0041; respiratory-related complications during the perioperative period, P = 0.0032; and postoperative psychological/psychiatric adverse events, P = 0.0152). Conclusion: The combination of intranasal dexmedetomidine 2 mu g/kg and oral ketamine 3 mg/kg produces satisfactory separation from parents and more successful venous cannulation, allowing children to smoothly accept induction of general anesthesia.