Effectiveness of vapocoolant spray compared to eutectic lidocaine/prilocaine cream to enhance tolerance during intravenous catheterisation: a randomised controlled trial.

Objectives: To determine if tolerance of intravenous catheterisation differs following the application of vapocoolant spray compared to lidocaine/prilocaine cream in dogs and cats.

Materials And Methods: A randomised controlled trial of client-owned dogs and cats requiring intravenous catheterisation was performed. They were randomly allocated to either have lidocaine/prilocaine cream applied to their skin 1 hour prior to intravenous catheterisation or a swab saturated with vapocoolant spray applied immediately prior to intravenous catheterisation. The procedure was video-recorded and a single blinded observer reviewed the recordings and assigned reaction scores (0 to 3) at 4 time points (initial restraint, limb handling, swab application and skin puncture).

Results: Between October 2020 and March 2022, a total of 101 animals (83 dogs and 18 cats) were enrolled, with 56 patients randomised to receive vapocoolant spray and 45 to receive lidocaine/prilocaine cream. There was no significant difference in the age, sex status, number of cross and pure breeds, and mentation detected between the groups. There was no significant difference in reaction scores between the treatments when comparing all patients at any time point except for a significantly increased swab application reaction score in patients receiving vapocoolant spray. Vapocoolant spray was significantly less effective in reducing adverse reaction to skin puncture than lidocaine/prilocaine cream in the small number of cats evaluated.

Clinical Significance: When considering all patients together, no single method of anaesthesia appeared superior for improving tolerance of intravenous catheter placement. However, vapocoolant spray may be less effective than lidocaine/prilocaine cream in reducing adverse response to skin puncture during catheterisation in cats.