Lignocaine ointment and local anaesthesia in preterm infants.

The ability of topically applied lignocaine ointment to produce surface anaesthesia was examined in 45 preterm infants (gestational age 25 to 35 weeks) at a median age of 2 days. Two strengths of ointment, 5% and 30%, were tested at 30 and 60 minutes after application to the dorsum of the foot. Anaesthesia was assessed by comparing the response to skin stimulation at the test and control sites, using von Frey hairs. In 84% of cases responses indicated that there was no surface anaesthesia. Topically applied lignocaine ointment is not an effective local anaesthetic in preterm infants, presumably due to poor absorption.