Allergy and contrast media.

Abstract

. THE allergic origin of severe reactions following the injection of iodinated contrast media (ICM) is disputed. However, three publications argue that immediate hypersensitivity is probably due to IgE mediation (1±3). The description of clinical signs and measurement of mediators (histamine, tryptase) play an important role since cutaneous tests and speci®c IgEs are not validated for ICMs. We report ®ve clinical cases of severe reactions (including one death) occurring after an intra-arterial injection of the same ionic ICM in three patients and two nonionic ICMs in two other patients (Table 1). The clinical symptoms corresponded in each case to the grade III (4) minimum. All the patients had been in contact with the culprit ICM at least once (prior exposure). Treatment with intravenous epinephrine was successful in four cases. One patient died from cardiovascular collapse followed by multiorgan failure 16 h after the injection. Measurement of mediators (histamine and tryptase) was done. After the patients gave informed consent, prick tests and intradermal tests (IDT) were carried out 6 weeks after the incident to identify the culprit ICM. A prick test with pure ICM on the forearm, is positive if 15 min later a wheal appears which is equal to at least half the positive control (using an extract of codeine phosphate at 9%) and larger than the negative control (saline solution). An IDT is done on the patient's back by injecting 0.15 ml of ICM at a concentration ranging from 10 to 10, raising a bleb of about 3 mm. The IDT is positive if 15 min Five cases of severe anaphylactoid reactions.