Dripping lidocaine onto the skin prior to lidocaine injection may help reduce injection-associated procedural pain, according to the results of a randomized clinical trial published in Chest.
A total of 481 patients with a planned medical bedside procedure that necessitated the use of local lidocaine injection for analgesia (eg, peripheral insertion of a central catheter, lumbar puncture) were randomly assigned to have approximately 1 mL to 2 mL of 1% lidocaine dripped onto the skin’s surface immediately before subcutaneous injection of 1% lidocaine (intervention; n=244) or receive an injection only (control; n=237).
The severity of procedural pain — assessed with the 0 to 100 mm visual analogue scale (VAS) — was the study’s primary outcome.
Study participants in the intervention vs control group reported lower VAS scores (12.2±19.4 mm vs 16.6±24.8 mm, respectively; P =.03). In a subgroup analysis, patients in whom a peripherally inserted central catheters was installed had the greatest reduction in pain with the intervention compared with the control group (18.8±25.6 mm vs 12.2±18.2 mm, respectively; P =.02).
“Lidocaine dripped onto the skin from the syringe is water soluble and has no direct anesthetic effect; rather, we hypothesize that it is the room temperature solution on the skin (cooler temperature than skin body temperature) that generates sensory nerve traffic within the spinal cord dorsal horn that can ‘gate’ or inhibit the noxious signal from the lidocaine injection,” concluded the study authors.
Patel BK, Wendlandt BN, Wolfe KS, et al. Comparison of two lidocaine administration techniques on perceived pain from bedside procedures: A randomized clinical trial [published online April 23, 2018]. Chest. doi:10.1016/j.chest.2018.04.018