Anaesthetic allergy: Overview

Abstract
Introduction Anaphylaxis, although rare, can occur in dental settings. While local anaesthetics (LAs) are widely used in dentistry, true allergic reactions to LAs are uncommon. Most adverse reactions associated with their use are non-allergic in nature, often resulting from factors such as vasovagal syncope, toxicity, or procedural trauma. The overlap in clinical presentation makes distinguishing true allergic reactions from other causes particularly challenging.Aims To determine the prevalence of true LA allergies and characterise the nature of adverse drug reactions (ADRs) following LA administration.Design Retrospective, observational study.Materials and methods Data from 37 patients referred with suspected LA allergies (December 2021 to June 2024) were analysed. Skin prick testing, intradermal testing, and drug provocation tests were performed to assess ADRs and identify potential allergens, including co-administered medications.Results None of the patients tested positive for immunoglobulin E (IgE)-mediated LA allergies. Four patients had allergies to co-administered agents, while other reactions were non-allergic, including vasovagal syncope and procedural trauma.Discussion True IgE-mediated LA allergies are rare. Non-allergic reactions, such as vasovagal syncope and toxicity, are more common and often misinterpreted as allergies.Conclusion Accurate diagnosis is essential to distinguish between true allergies and non-allergic reactions, especially in dental settings. Enhanced training can help reduce misdiagnosis and unnecessary interventions.

Abstract
Background: Few data are available regarding the morbidity of patients who have experienced anaphylaxis because of neuromuscular blocking agents (NMBAs). This study aimed to describe the outcomes and impact on future anaesthesia in these patients.

Methods: This retrospective single-centre study analysed data from adult patients receiving NMBAs during general anaesthesia from 2012 to 2022 at Lille University Hospital (Lille, France) who also experienced a grade II, III, or IV NMBA-related anaphylaxis. Data were collected using an electronic data warehouse and through individual review of medical records.

Results: Among the 158 021 general anaesthetics including an NMBA, 94 patients experienced perioperative anaphylaxis, with 82 confirmed by an allergist. This incidence of 58.1 reactions per 100 000 administrations of NMBAs, all agents combined, is higher than that described in the literature. Reporting to a pharmacovigilance centre occurred in only 14.9% of cases. Four patients died within 90 days, and 19 patients (20%) experienced morbidity, including renal failure (n=12), cardiovascular complications (n=8), and neurological complications (n=4). Out of those 19 patients with morbidity, 12 made a full recovery. In the 96 subsequent anaesthetic procedures screened, surgery was successfully completed without the use of NMBAs.

Conclusions: This study highlighted a significant underestimation of the incidence of perioperative anaphylaxis related to neuromuscular blocking agents and reporting to the local and national pharmacovigilance centre despite allergy assessment. Morbidity occurred in 20% of patients, primarily involving renal and cardiovascular complications, with most patients making a full recovery. The impact on subsequent anaesthesia is limited, as procedures can typically be performed without use of neuromuscular blocking agents.