Topical amethocaine gel for pain relief of heel prick blood sampling: a randomised double blind controlled trial.

BACKGROUND Heel prick blood sampling is a commonly performed and painful procedure in the newborn infant. Use of a topical local anaesthetic does not relieve this pain. A 4% w/w amethocaine gel (Ametop) reduces the pain of venepuncture in the newborn but has not been tried with heel pricks. AIM To investigate the effect of topical amethocaine gel on the pain of heel prick in the newborn infant. DESIGN Randomised, double blind, placebo controlled trial. SUBJECTS Sixty newborn infants, gestation 28-42 weeks (median 36), postnatal age 1-16 days (median 5) undergoing routine heel prick blood sampling. METHODS A 1.5 g portion of 4% w/w amethocaine gel or placebo was applied to the skin under occlusion for one hour, then wiped away. Heel prick blood sampling with a spring loaded lance was performed five minutes later. The procedure was videotaped and pain assessed at one second intervals using an adaptation of the neonatal facial coding system (NFCS). No or minimal pain was defined as a cumulative score of less than 5 (out of 15) in the three seconds after firing of the lance and as lack of a cry in the first five seconds. RESULTS In terms of a low NFCS core and lack of cry (p = 0.12) 20 of 30 (67%) in the amethocaine group and 13 of 29 (45%) in the placebo group had no or minimal pain in response to the heel prick. The median cumulative NFCS score over the three seconds after firing the lance was 3 (interquartile range 0-6) in the amethocaine group compared with 5 (interquartile range 1-10) in the placebo group (p = 0.07). These differences are not significant. CONCLUSIONS Topical amethocaine gel does not have a clinically important effect on the pain of heel prick blood sampling and its use for this purpose cannot therefore be recommended. Alternative approaches to the relief of pain from this procedure should be explored.