Analgesia during radial artery cannulation: comparison of the effects of lidocaine applied by local injection or iontophoresis.
We compared the effect of lidocaine injection with lidocaine iontophoresis for pain relief during radial artery cannulation prior to induction of anaesthesia. Patients were allocated randomly to one of two groups. Group 1 (n = 15) received iontophoresis for 10 min prior to cannulation, using 4% lidocaine 4 ml. Group 2 (n = 15) received local infiltration of 1% lidocaine 1 ml using a 25G needle. Pain scores were recorded immediately after cannulation using a 10-cm visual analogue scale (VAS). There was no difference in mean (SD) pain scores [group 1: 2.2 (1.5) cm; group 2: 2.3 (2.7) cm; 95% CI of difference -1.8 to 1.5 cm]. Lidocaine delivered by iontophoresis is an effective and painless method of providing analgesia for radial artery cannulation.