Local anaesthetic effect of topical amethocaine gel in neonates: randomised controlled trial

摘要

AIM—To assess theefficacy of amethocaine as a topical local anaesthetic in neonates.
METHODS—A randomised,double blind controlled trial compared 4% amethocaine gel (Ametop)with placebo in 60 healthy neonates (29 to 42 weeks of gestation) inthe first week after birth. Either 1.5 g 4% w/w amethocaine (gel) or1.5g placebo gel were applied to the dorsum of one foot. No gel wasapplied to the other foot. Each foot was occluded and left for onehour. Local anaesthesia was then assessed by eliciting the cutaneouswithdrawal reflex in response to stimulation with a series of gradednylon filaments (von Frey hairs). The reflex was first elicited fromthe control and then the treated foot. The difference in filamentthickness and deforming weight required to elicit the reflex was recorded.
RESULTS—In infantstreated with amethocaine, 17 of 31 (54.8%) showed evidence of localanaesthetic action compared with five of 29(17.2%) in the placebogroup (p=0.003). The mean difference in deforming weight required toelicit the reflex was 18.8 g in the amethocaine group compared with 3.9 g in the placebo group (p=0.02). The apparent local anaesthetic actionof the placebo can be explained by habituation to repeated stimulation.
CONCLUSIONS—It isconcluded that topical amethocaine gel has a local anaesthetic actionon neonatal skin which merits further investigation. An effective andsafe surface local anaesthetic would be valuable for the relief ofprocedure related pain in neonates.