Relative effectiveness of lignocaine-prilocaine emulsion and nitrous oxide inhalation for routine preoperative laboratory testing

We studied the impact of age-related factors and the benefits of 50% nitrous oxide or EMLA cream in 108 children undergoing preoperative laboratory testing. Procedural pain was assessed by behavioural scores (CHEOPS) and pain intensity ratings. Age, preexisting behavioural distress and difficulty of venous access were significant predictors of outcome in univariate analysis. Nitrous oxide and EMLA cream were both effective in lowering pain related behaviour and pain ratings generated by the different adult observers and the children where applicable. EMLA cream was more effective than 50% nitrous oxide in children 1-4 years old. Although EMLA cream was responsible for a 28+/-5 min prolongation of waiting time at the clinic, the present results suggest that it should remain the first line intervention to alleviate pain from venepuncture in paediatric outpatients.