TITLE: LOCAL ANESTHESIA FOR VENOUS AND ARTERIAL ACCESS: COMPARISON OF JET INJECTION WITH NEEDLE INFILTRATION

AUTHORS: Joel O. Johnson, MD-PhD¹, Steven E. Kern, PhD², Julia L. White, RN, BS, CCRC²
AFFILIATION: ¹University of Missouri-Columbia, Columbia, MO; ²University of Utah, Salt Lake City, UT.

INTRODUCTION: Infiltration of the skin with local anesthetic prior to venous or arterial catheter insertion is preferred by patients when compared to no local anesthesia.¹ Alternatives to needle injection include iontophoresis of lidocaine² and application of EMLA (eutectic mixture of local anesthetics) cream³ which suffer from a delay in onset. In contrast, jet injection of local anesthetic is immediately effective and reduces needle exposure. This prospective, randomized study was designed to compare jet injection of local anesthetic with subcutaneous needle injection prior to venous catheter insertion. The effect of jet injection of local anesthetic before radial artery puncture was evaluated also.
METHODS: After IRB approval, 24 (12 female/12 male) ASA 1 volunteers from the general population gave informed consent. Subjects received an injection of 1% lidocaine in each ventral forearm, with random assignment to the arm injected, type of injection and volume of jet injectate (0.05-0.2 ml). The volunteer was asked to rate the pain of injection on a scale of one to ten. Thirty seconds later, the area of anesthesia was determined using a 27 gauge dental needle. IV access was attempted with an 18 gauge Insyte® catheter and a pain rating obtained. Pain assess- ments were obtained after jet injection and radial artery puncture.
RESULTS: The median pain score (MPS) reported from jet injection and from needle injection was low (MPS=2) and did not differ between techniques. Volume of jet injectate did not alter the reported pain on injection or increase the analgesic area. The area of analgesia was significantly greater after the needle injection compared to the jet injection (p=0.008). Pain on venous cannulation was rated greater after jet injection (MPS=2.5) than needle infiltration (MPS=0.0, p<0.001). The MPS for arterial puncture after jet injection was 0.0, (25%-75% range 0-1).
CONCLUSIONS: Dermal anesthesia is minimally painful in adult volunteers, regardless of whether it is administered by jet injector or 30 gauge needle. IV catheter insertion was more painful after jet injection than after subcutaneous infiltration analgesia. Prior to radial artery puncture, jet injection was effective in decreasing pain. These differences may reflect anatomic variation at the injection site, which influence injectate spread.
REFERENCES:

1.) J Royal Coll Phys London 11-1997; 31(6): 645-646.

2.) Clin J Pain 3-1997; 13(1): 22-26.

3.) Can J Anaes 8-1997; 44(8): 798-802.