The use of glyceryl trinitrate ointment with EMLA cream for i.v. cannulation in children undergoing routine surgery

This prospective randomized controlled double-blind trial was performed to investigate whether glyceryl trinitrate (GTN) ointment, applied ten minutes after the removal of a eutectic mixture of local anaesthetic cream, lignocaine/ prilocaine (EMLA), influences site selection for intravenous cannulation in children. Eighty children aged between five and 15 years, having general surgery as day patients, received EMLA cream on both hands for 90 minutes prior to transfer to the theatre suite. Acting as their own controls, the children received GTN on one hand, and placebo on the other, after removal of the EMLA cream and ten minutes prior to the insertion of an intravenous cannula. The application of GTN or placebo to left or right hand was blinded and randomized. At induction, the hand with the visually best quality veins was selected and cannulated. The primary outcome was selection between the EMLA/GTN hand and EMLA/placebo hand. The selection having been made, the number of attempts at cannulation, ease of insertion and pain scores (VAS) for cannulation were also recorded. The choice of hand was positively influenced by the use of GTN, with the GTN hand chosen in 51 of 72 (70%) children who completed the protocol (P = 0.001). The findings of this study suggest that the application of GTN after EMLA removal may be clinically useful in aiding cannulation in children.