Neuromuscular blocking agent drug challenge: a literature review and protocol proposal with biological evaluation.

Background: Drug challenge is the gold standard for identifying causative agents of drug allergies. Although clinical guidelines have recently been published, they do not recommend neuromuscular blocking agent (NMBA) drug challenges. NMBA challenges are rendered difficult by the lack of homogeneity of routine allergy work-ups and the necessity of a specialised setting. Several scenarios support NMBA challenges, such as an ambiguous allergy work-up, a high suspicion of a false-positive skin test or identification of a well tolerated alternative NMBA strategy. Furthermore, routine allergy work-ups may not recognise non-IgE mechanisms, such as IgG or MRGPRX2, whereas drug challenges may reveal them. Finally, if the culprit NMBA is not identified, subsequent anaesthesia regimens will be challenging to implement, resulting in increased risk.
Objectives: This literature review discusses the indications, strategies, doses, monitoring methods, limitations, and unresolved issues related to drug challenges for NMBAs.
Design: The literature review included randomised controlled trials, observational studies, reviews, case reports, series, and comments on humans.
Data Sources: Studies were retrieved from databases (PubMed) and electronic libraries (OVID, EMBASE, Scopus, etc.).
Eligibility Criteria: All studies that referred to the NMBA challenge were included without publication date limitations.
Results: NMBA challenge may be considered in NMBA anaphylaxis patients with inconclusive or ambivalent IgE diagnostic work-up under controlled conditions (presence of anaesthetists and allergists with continuous monitoring in a secured environment). To illustrate its utility, a case report of a double NMBA challenge in a patient with NMBA cross-reactivity is presented, along with biological explorations to detect subclinical cellular activation, a novel aspect of this procedure.
Conclusion: Drug challenges could be implemented during the NMBA allergy work-up under strict safety conditions at specialised centres with close collaboration between anaesthetists and allergists. This could decrease uncertainty and contribute to defining a safer strategy for subsequent anaesthetic drug regimens.
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