[Risk factors in anaphylactoid reactions to muscle relaxants. A retrospective study of 103 cases of shock].

A homogeneous series of 103 cases of shock due to muscle relaxants has been used to identify the risk factors in anaphylactoid shocks due to either true anaphylaxis or to non-specific histamine release. Clinical atopy (asthma) and sub-clinical atopy as shown up by skin tests with mites and pollens, as well as a history of IgE-dependent drug allergy, were present with a significantly greater frequency in the history of patients presenting with anaphylaxis. Abnormal histamine release and reactivity to histamine, as assessed by skin tests with 48/80 and histamine, were often found in those patients who presented with non-specific histamine release induced by muscle relaxants. Whatever the mechanism for the shock, the frequency of spasmophilia was increased. A history of non-immunological intolerance to acetyl salicylic acid and other non-steroid anti-inflammatory drugs was more often found than in the reference drugs was more often found than in the reference population. However, 25% of the patients studied did not have any of these risk factors. Several possibilities of preventing anaphylactoid reactions are given, if one or more of these risk factors are found in the history: a better choice of anaesthetic drugs, in the light of previous anaesthetic protocols, the relief of anxiety by appropriate premedication, antihistamine premedication and the prevention of bronchospasm.