Radial artery cannulation: topical amethocaine gel versus lidocaine infiltration

Abstract

In a prospective randomized study, we compared topical 4% amethocaine gel (Ametop) with 2% lidocaine infiltration for analgesia for radial artery cannulation. A previous study had shown topical analgesia with EMLA cream reduced pain, shortened cannulation time, and improved success rates when compared with lidocaine infiltration. One hundred adult patients undergoing elective cardiac surgery were randomized. Cannulation times and success rates were compared between the two groups. The quality of analgesia was assessed using a visual analogue scale (VAS) and four-point verbal pain scoring system. Ninety-nine sets of data were analysed using Mann-Whitney U and chi-squared tests. Mean time to cannulation was 56 s in the amethocaine group (interquartile range (IQR) 41-142) and 59 s in the lidocaine group (IQR 40-105). The median pain score on the VAS was 2 in both groups (IQR 1-3.5 for amethocaine and 0-4 for lidocaine). There was no significant difference between these two methods of analgesia for any measured variable.