You have to close a laceration in a 5 year old and you’re preparing your local anesthesia. It’s been shown that buffering lidocaine with bicarbonate decreases the acidity of the solution and improves patient comfort during infiltration, but have you considered warming it?

Brogan et al found in a study of 45 patients that buffering with bicarbonate in a 10:1 ratio (9ml of lidocaine, 1ml of 8.4% Sodium Bicarbonate) decreased pain scores upon infiltration. Additionally, warming the lidocaine solution decreased pain scores during injection. Interestingly, both warmed and buffered lidocaine did not statistically reduce pain scores on infiltration. Both modifications were as efficacious as plain lidocaine.

Brogan GX, Giarrusso E, Hollander JE, et al. Comparison of plain, warmed, and buffered lidocaine for anesthesia of traumatic wounds. Ann Emerg Med. 1995 Aug;26(2):121-5.