Anaphylaxis during general anaesthesia - Prevention and management

Any drug administered in the peri-operative period has the potential to produce life-threatening immune-mediated anaphylaxis, The incidence of anaphylaxis has been estimated at between 1 in 10 000 and 1 in 20 000 anaesthesias in Australia and 1 in 13 000 anaesthesias in France. In the most recent French epidemiological survey, the compounds most frequently involved in anaphylaxis were muscle relaxants (60%), followed by latex (16%). Activation of humoral and cellular pathways resulting from immunoglobulin E-mediated adverse reactions usually produces characteristic respiratory, cardiovascular and skin responses, but effects can be seen in virtually any system. These responses may occur as isolated clinical events. As a result, an anaphylactic reaction restricted to a single clinical symptom (e.g.. bronchospasm, tachycardia) can easily be misdiagnosed. Intra- and postoperative investigations must be performed to confirm the nature of the adverse reaction, the role of the suspected drugs, and to define precise recommendations for future anaesthesias. The patient must be fully informed, and given a detailed written account of the anaphylactic episode, the results of the allergological assessment performed and the resulting recommendations. Furthermore, the patient should be strongly advise to wear a warning bracelet or carry a warning card. Since no specific treatment has been proven to reliably prevent the onset of anaphylactic reactions, allergological assessment must be performed in all high risk patients. The only possible strategy is to avoid the drug tested positively during the allergy work-up. Nevertheless, in cases where muscle relaxants are incriminated, patients allergic to one muscle relaxant can be administered another agent, the choice of which is based on skin test results. However, it should be borne in mind that rare cases of adverse reactions in spite of such screening procedures have been reported. On the contrary, there is no indication for allergological assessment in atopic patients who do not have additional anaesthetic agent risk factors or those allergic only to non-anaesthetic substances. The treatment of anaphylaxis is aimed at interrupting contact with the responsible antigen, modulating the effects of released mediators, and inhibiting mediator production and release. Treatment must be initiated as quickly as possible, and relies on generally accepted principles.