The effective time and concentration of nitrous oxide to reduce venipuncture pain in children

Study Objective: To investigate the time of administration and concentration of inhaled nitrous oxide (N2O) needed to reduce the pain associated with intravenous (IV) cannulation in children. Design: Prospective, randomized study. Setting: Operating room of a children's hospital. Patients: 73 ASA physical status 1 and 11 children, aged 6-15 years, scheduled for elective day or non-day surgery. Interventions: Children were randomly allocated to one of 4 groups prior to IV insertion of a 24-gauge catheter in the dorsum of the hand: Group 1 (n = 18): 50% N2O in O-2 for three minutes; Group 2 (n = 18): 50% N2O in O-2 for 5 minutes; Group 3 (n = 18): 70% N2O in O-2 for three minutes; or Group 4 (n = 19): 70% N2O in O-2 for 5 minutes. Measurements: Just after the venous cannulation, degree of pain was assessed by examining the faces of the patient by the parent and an operating room nurse. Main Results: Pain scores obtained from parents of children in Groups 3 and 4 were significantly lower than from those in Groups 1 and 2. Pain scores from the nurse in Group 3 was significantly lower than those in Group 1. However, there was no significant difference in pain score between Group 3 and Group 4. Frequency of side effects was similar among the 4 groups. Conclusions: Seventy percent N2O in O-2 given for three minutes was effective for reducing venipuncture pain in children. (C) 2009 Elsevier Inc. All rights reserved.