In children, nitrous oxide decreases pain on injection of propofol mixed with lidocaine

Abstract

Purpose: To investigate if 50% nitrous oxide reduces the pain during injection of propofol mixed with lidocaine in children. Methods: Healthy children undergoing iv induction of general anesthesia for elective surgery were recruited into this prospective, randomized, double-blind study. None of the patients received any premedication except for eutectic mixture of local anesthetics cream. Before induction of anesthesia with propofol 1% mixed with lidocaine 0.05% (propofol dose 3 mg·kg-1), the treatment group received 50% N2O in O2 and the control group received 100% oxygen. Pain due to propofol administration was rated with a four-point behavioural scale: none, mild, moderate or severe. Results: There were 28 subjects in the control group and 26 subjects in the treatment group. Demographic data were similar in both groups. The incidence of pain at induction was 4% after N2O and 36% in the control group, P < 0.01. No patients had severe pain. Most patients had mild pain. Three of the ten patients with pain in the control group had moderate pain. The number needed to treat was 3:1. Conclusion: Nitrous oxide reduces pain during induction with propofol mixed with lidocaine in healthy children.