Objective: Palivizumab (Synagis [Abbot Laboratories, Kent, United Kingdom]) is recommended for the prevention of severe lower respiratory tract infections caused by respiratory syncytial virus in infants at high risk. These injections are very painful, and currently the use of analgesics is not systematic. The objective of this study was to compare the efficacy of EMLA with premixed 50% nitrous oxide/oxygen, used alone or combined with EMLA, for pain alleviation during palivizumab injections.
Methods: This randomized, double-blind, multicenter study included children who were younger than 24 months. Each child randomly received during the first 3 monthly injections 3 different analgesic interventions: (1) EMLA: application of EMLA plus air inhalation; (2) nitrous oxide/oxygen: inhalation of 50/50 nitrous oxide/oxygen plus application of a placebo cream; and (3) nitrous oxide/oxygen plus EMLA: inhalation of 50/50 nitrous oxide/oxygen plus application of EMLA. Each child was his or her own control. Procedural pain was assessed through videotapes with the Modified Behavioral Pain Scale. The procedure itself was subdivided in 2 periods: (1) injection and (2) recovery (first 30 seconds after the removal of the needle). Modified Behavioral Pain Scale scores over time (injection and recovery periods) and among treatments were compared by repeated-measures analysis of variance.
Results: Fifty-five children were included. Mean +/- SD Modified Behavioral Pain Scale pain scores for EMLA, nitrous oxide/oxygen, and nitrous oxide/oxygen plus EMLA were, respectively, 9.3 +/- 1.0, 8.8 +/- 1.2, and 8.2 +/- 1.8 during the injection and 7.8 +/- 1.7, 7.4 +/- 1.9, and 6.9 +/- 2.4 during the recovery period. A significant time and treatment effect in favor of the combined nitrous oxide/oxygen plus EMLA was observed.
Conclusions: The administration of 50/50 nitrous oxide/oxygen to infants and young children is effective in decreasing the pain associated with palivizumab intramuscular injections. The combined nitrous oxide/oxygen plus EMLA cream was more effective than either EMLA cream or nitrous oxide/oxygen alone.