Agreement of a clinical scoring system with allergic anaphylaxis in suspected perioperative hypersensitivity reactions: prospective validation of a new tool.

BACKGROUND: A clinical scoring system to estimate the likelihood that a reaction represents a perioperative immediate hypersensitivity reaction has been devised using a Delphi consensus process. Agreement of this clinical scoring system with the outcome of allergological assessment would allow the use of this tool in post-resuscitation and subsequent management of suspected perioperative immediate hypersensitivity reaction and potentially as a new standard reference for clinical investigations. METHODS: We prospectively scored 301 cases of suspected perioperative immediate hypersensitivity reaction according to the Hypersensitivity Clinical Scoring Scheme. Classification of cases was by allergological workup based on immediate and delayed investigations. The discrimination and calibration of the Hypersensitivity Clinical Scoring Scheme was compared with results from an expert panel of allergologists, skin testing, mast cell tryptase ratios, and specific IgE assays, as was agreement by Cohen's kappa coefficient. RESULTS: The Hypersensitivity Clinical Scoring Scheme predicted cases of allergic perioperative immediate hypersensitivity reaction with comparable discrimination to an expert panel, mast cell tryptase formula, and specific IgE assays in anaphylaxis to neuromuscular blocking drugs. Using a score threshold of 15 or greater to indicate allergic perioperative immediate hypersensitivity reaction, the sensitivity was 88.9%, with a specificity of 79.4%. Prospectively, the Hypersensitivity Clinical Scoring Scheme correctly classified a greater number of subjects than the expert panel and the optimal post hoc binary logistic regression model (86% vs 85% vs 84%), however it was inferior to skin testing. CONCLUSION: The Hypersensitivity Clinical Scoring Scheme predicts allergic perioperative immediate hypersensitivity using features of the acute syndrome. This approach could guide algorithms for the post-resuscitative management of suspected perioperative immediate hypersensitivity, and identify patients requiring drug provocation challenge.

Relationship of perioperative anaphylaxis to neuromuscular blocking agents, obesity, and pholcodine consumption: a case-control study.

BACKGROUND: The observation that patients presenting for bariatric surgery had a high incidence of neuromuscular blocking agent (NMBA) anaphylaxis prompted this restricted case-control study to test the hypothesis that obesity is a risk factor for NMBA anaphylaxis, independent of differences in pholcodine consumption. METHODS: We compared 145 patients diagnosed with intraoperative NMBA anaphylaxis in Western Australia between 2012 and 2020 with 61 patients with cefazolin anaphylaxis with respect to BMI grade, history of pholcodine consumption, sex, age, comorbid disease, and NMBA type and dose. Confounding was assessed by stratification and binomial logistic regression. RESULTS: Obesity (odds ratio [OR]=2.96, χ2=11.7, P=0.001), 'definite' pholcodine consumption (OR=14.0, χ2=2.6, P<0.001), and female sex (OR=2.70, χ2=9.61, P=0.002) were statistically significant risk factors for NMBA anaphylaxis on univariate analysis. The risk of NMBA anaphylaxis increased with BMI grade. Confounding analysis indicated that both obesity and pholcodine consumption remained important risk factors after correction for confounding, but that sex did not. The relative rate of rocuronium anaphylaxis was estimated to be 3.0 times that of vecuronium using controls as an estimate of market share, and the risk of NMBA anaphylaxis in patients presenting for bariatric surgery was 8.8 times the expected rate (74.9 vs 8.5 per 100 000 anaesthetic procedures). CONCLUSIONS: Obesity is a risk factor for NMBA anaphylaxis, the risk increasing with BMI grade. Pholcodine consumption is also a risk factor, and this is consistent with the pholcodine hypothesis. Rocuronium use is associated with an increased risk of anaphylaxis compared with vecuronium in this population.

Anaphylaxis to intravenous paracetamol containing povidone. A case report and narrative review of excipient allergy related to anaesthesia.

Investigation of intraoperative anaphylaxis includes the exclusion of potential trigger agents the individual was exposed to within a plausible interval preceding the reaction. Occasionally, none of these agents will test positive. In this situation it is important to consider that excipients may be responsible for anaphylaxis, that the dilutions prepared to test the medication may not contain an appropriate concentration of the excipient to induce a positive skin reaction, or if an alternative formulation of the medication is tested, it may not contain the culprit excipient. This case describes a patient, who previously experienced an anaphylactic reaction to Betadine® (Sanofi-Aventis Australia Pty Ltd, North Ryde BC, NSW) experiencing anaphylaxis in the recovery period after general anaesthesia where Betadine was avoided. The recently administered therapeutics were excluded by skin testing, however further investigation determined that a povidone-containing formulation of paracetamol had been administered. Skin testing with povidone-containing paracetamol resulted in a positive reaction in the patient, but not in a volunteer control. Pharmaceutical excipients are added to medications to increase absorption, shelf-life and efficacy. Different brands of the same drug may contain different excipients. When testing for anaphylaxis with such compounds one must be sure the dilution is appropriate for both the parent compound and the excipient to ensure the accuracy of skin-prick and intradermal testing. This case demonstrates the potential for excipients to cause severe allergy and the importance of detailed history pertaining to previous allergic episodes as even the most unlikely of medications can potentially result in anaphylaxis due to excipients.