Allergic risk in anaesthesia

Anaphylactic reactions may be either of immune (allergy, usually IgE-mediated, sometimes IgG-mediated) or non-immune origin. The incidence of anaphylactic reactions during anaesthesia varies between countries ranging from 1/1250 to 1/13,000 per procedure. In France, the estimated incidence of allergic reactions is 100.6 [76.2-125.3]/million procedures with a high female predominance (male: 55.4 [42.0-69.0], female: 154.9 [117.2-193.1]). This predominance is not observed in children. In adults, the most frequently incriminated substances are neuromuscular blocking agents, followed by latex and antibiotics. The estimated incidence of allergic reactions to neuromuscular blocking agents is 184.0 [139.3-229.7]/million procedure. In most cases there is a close reaction between clinical symptoms and drug administration. When the reaction is delayed, occurring during the surgical procedure, a reaction involving latex, a vital dye, an antiseptic or a volume expanding fluid should be suspected. Reaction severity may vary. The most frequently reported initial symptoms are pulselessness, erythema, increased airway pressure, desaturation or decreased end-tidal CO2. Clinical symptoms may occur as an isolated condition, making proper diagnosis difficult. In some cases a cardiovascular arrest can be observed. Reaction mechanism identification relies on mediators (tryptase, histamine) measurement at the time of the reaction. In case of allergic reaction, the responsible drug can be identified by the detection of specific IgE using immunoassays or by skin tests performed 6 weeks after the reaction. Predictive allergy investigation to latex or anaesthetics in the absence of history of reaction should be restricted to at-risk patients. Premedication cannot prevent the onset of an allergic reaction. Providing a latex-free environment can be used for primary or secondary prevention. Treatment is based on allergen administration interruption, epinephrine administration in a titrated manner based on symptoms severity, and on volume expansion.