APPROACH TO THE PATIENT WITH A HISTORY OF LOCAL-ANESTHETIC HYPERSENSITIVITY - EXPERIENCE WITH 90 PATIENTS

The utility of skin testing and progressive challenge were studied to detect local anesthetic hypersensitivity in patients with histories of reactions to local anesthetics. The likelihood of previous immediate hypersensitivity reactions was determined by history in 90 referrals. Fourteen had histories compatible with immediate hypersensitivity reactions, 24 did not, and the history was uncertain in 52. Of the 14, 12 were negative to lidocaine skin test and challenge, although 5 gave histories of immediate hypersensitivity reactions to it. The other 76 patients also underwent skin testing and progressive challenge. No skin tests were positive with 1:100 local anesthetics but 10 patients had positive intradermal skin tests to undiluted 1% local anesthetics. Proof of false positivity was confirmed in 4 of 10 cases by uneventful challenge to the local anesthetic giving the positive skin test. At least 1 local anesthetic was cleared for use in each of the 90 patients. Skin testing as part of a progressive challenge protocol is useful in the management of alleged local anesthetic hypersensitivity. True immediate hypersensitivity reactions to local anesthetics are rare. Positive skin tests to dilutions of 1:100 local anesthetics are also rare and may suggest the possibility of true immediate hypersensitivity to the agent tested.