[Anaphylactic reaction to epidural block in an outpatient]

A healthy 29-year-old woman received epidural block for severe lumbago in an outpatient clinic. Fifteen minutes after injection of mepivacaine 0.5% with dexamethasone into the epidural space, the patient complained of itching of eyelids followed by generalized pruritus. Hypotension, erythema and generalized urticaria were observed. Initial treatment was with 100% oxygen through face mask, and additional intravenous fluids, followed by administration of adrenaline, chlorpheniramine and dopamine. Cardiac ultrasound examination showed mildly impaired movement of inferior to septal wall. Her plasma histamine level was transiently elevated during the anaphylactic event; however the serum tryptase level was not. Biological assays for confirming the causative agent and cutaneous test were all negative, but clinical symptoms positivity showed nonimmunological anaphylactic reaction to mepivacaine or dexamethasone. This case report confirms the need for systematic allergological investigation in a case of immediate hypersensitivity reaction occurring during nerve block in patients who had even received similar nerve blocks repeatedly. Pain clinician should be aware of the possibility of anaphylactic reactions involving any drug or substance used for an outpatient.