[Reproducibility of intradermal tests after anaphylaxis caused by muscle relaxants]

Intradermal tests with 5 muscle relaxants were performed on two occasions in 56 patients who had experienced an adverse event during general anaesthesia: anaphylactoid reaction with at least one positive test 19.5 +/- 13.5 months previously in 50 cases; adverse reaction unrelated to muscle relaxants and with negative tests 21 +/- 6.4 months previously in 6 cases. Sixteen healthy subjects who had never been tested served as controls; their tests were all negative. The reproducibility of 244 assessable tests in the 56 patients reached 88.1%. Twenty-three (9.4%) of the tests previously positive had become negative and six (2.5%) of the tests previously negative had become positive. Tests performed with pancuronium or vecuronium had more often become negative (47% and 40% respectively) than those performed with the other 3 muscle relaxants tested (P less than 0.001). These results suggest that skin tests should be repeated prior to general anaesthesia in all patients who previously developed an anaphylactoid reaction to muscle relaxants.