Reducing the Discomfort of Lidocaine Administration through pH Buffering

Abstract

A prospective, double-blind study was undertaken to evaluate the effect of using a buffered lidocaine solution on the perception of pain experienced by a patient during its intradermal injection. One hundred fifty patients undergoing diagnostic angiographic and interventional procedures at the authors' institution were randomly assigned to receive a 1-mL aliquot of one of three lidocaine solutions: plain 1% lidocaine, 1% lidocaine diluted with normal saline in a 10:1 ratio, and 1% lidocaine diluted with 8.4% sodium bicarbonate in a 10:1 ratio. The lidocaine solutions were administered intradermally over 10-15 seconds. A numerical value was placed on the patient's perception of pain, separate from that associated with the 25-gauge needle insertion, with use of a linear visual analog scale. Mean pain scores were as follows: for the 1% lidocaine solution, 2.83 +/- 2.60; for 1% lidocaine plus normal saline solution, 2.89 +/- 2.34; and for 1% lidocaine plus sodium bicarbonate solution, 1.37 +/- 1.73 (P = .0018). Buffering lidocaine significantly decreased the discomfort associated with its administration as a local anesthetic.