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Background: Neuromuscular blocking agents (NMBAs) remain the leading cause of perioperative anaphylaxis in Australia. Standard evaluation comprises history, skin tests, and in vitro specific immunoglobulin E tests. Drug provocation tests to suspected NMBA culprits are associated with a significant risk. Basophil activation testing (BAT) is a potentially useful in vitro test that is not commercially available in Australia or as part of standard evaluation., Methods: All patients attending the Anaesthetic Allergy Clinic in Sydney, Australia between May 2017 and July 2018 exposed to an NMBA before the onset of anaphylaxis during their anaesthetic qualified for the study. We recruited 120 patients sequentially who received standard evaluation plus BAT using CD63, CD203c, and CD300a as surface activation markers., Results: BAT results were expressed as % upregulation above the negative control and stimulation index (mean fluorescence index of stimulated sample divided by the negative control). We calculated cut-offs of 4.45% and 1.44 for CD63, and 8.80% and 1.49 for CD203c, respectively. Sensitivity was 77% with specificity of 76%. A subgroup of 10 patients with NMBA anaphylaxis had no sensitisation on skin tests. BAT using CD63 and CD203c showed sensitisation in six of these 10, and adding CD300a identified sensitisation in nine patients. BAT was positive in seven of nine patients with anaphylaxis of unknown aetiology., Conclusions: BAT may be a useful supplement to the standard evaluation in diagnosing NMBA anaphylaxis in patients with suggestive histories, but no sensitisation on skin tests. Ongoing study of this specific group of patients is required to clarify its utility in clinical practice., (Copyright © 2019 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.)

Background: Following diagnosis of neuromuscular blocking agent (NMBA) anaphylaxis, identifying safe alternatives for subsequent anaesthesia is critical. A patient with anaphylaxis to one NMBA can also have an allergic reaction to other NMBAs (cross-reactivity). Whilst drug provocation testing is standard for identifying or excluding allergy, there is significant risk. In vitro, after an allergen activates basophils, basophils express surface activation markers that can be measured by basophil activation testing (BAT). We compared cross-reactivity between NMBAs assessed by BAT against that by skin testing., Methods: All patients attending an anaesthetic allergy clinic in Sydney, Australia between May 2017 and July 2018 diagnosed with NMBA anaphylaxis qualified for this study comparing intradermal skin tests and BAT with a panel of NMBAs (rocuronium, vecuronium, pancuronium, suxamethonium, cisatracurium)., Results: Of the 61 patients participating, sensitisation on skin testing and on BAT completely matched in only nine patients (15%). Sensitisation was not in agreement for pancuronium, cisatracurium and rocuronium, but was in agreement for vecuronium and suxamethonium. Nine patients with negative skin tests subsequently tolerated cisatracurium, and one false positive on BAT to cisatracurium was detected., Conclusions: The utility of BAT in identifying safe NMBAs for subsequent anaesthesia needs further evaluation. BAT detects a different cross-reactivity profile to skin tests. Negative skin testing and BAT might increase confidence in performing drug provocation testing, but this and follow-up of subsequent anaesthesia in our cohort is necessary to determine the clinical significance of BAT sensitisation., (Copyright © 2019 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.)