Hypersensitivity reactions are rare events but have the potential to be life-threatening. They are relatively more common during general anaesthesia. This is potentially due to multiple drugs being administered concurrently. An 8-year-old, female neutered Labrador Retriever with bilateral cataracts was anaesthetised for right phacoemulsification. Soon after atracurium administration, the patient's heart rate (HR) increased, alongside decreases in arterial blood pressure and end tidal carbon dioxide (ETCO2). The dog was treated with clorphenamine and ephedrine intravenously (IV), while receiving a crystalloid fluids bolus. After 20 min both HR and blood pressure normalised, and the remainder of anaesthesia and recovery were uneventful. We suspected a non-allergic anaphylactic reaction to atracurium.
BACKGROUNDMost drugs administered during general anaesthesia have the potential to elicit allergic or non-allergic anaphylactic reactions. This current terminology, provided by the European Academy of Allergy and Clinical Immunology, 1 replaces the former distinction between anaphylactic and anaphylactoid reactions.Allergic anaphylaxis refers to the involvement of the immune system in the reaction of the body to a foreign antigen. The latter stimulates the production of specific immunoglobulin E (IgE) which binds to receptors on mast cell and basophil membranes. At subsequent exposures, the antigen binds to these specific IgE antibodies triggering the activation of a cascade that leads to the release of mediators such as histamine, cytokines, leukotrienes and prostaglandins and to the upregulation of nitric oxide. 2,3 Clinical manifestations may vary in severity and include signs in the skin (oedema, redness, weals, pruritus), gastrointestinal tract (abdominal pain, nausea, vomiting, diarrhoea), cardiovascular system (increased vascular permeability, vasodilation and hypotension) and respiratory system (increased mucous secretion, increased smooth muscle tone and bronchospasm). 4 Classically, these clinical manifestations were thought to occur only after sensitization via a previous exposure to an antigen. However, due to cross-linkages between drugs and other chemical compounds (toothpaste, detergent, nuts, chestnuts, avocado, cough medication), 5,6 severe anaphylaxis can also occur at first exposure. Examples of drugs that can be responsible for allergic reactions in susceptible individualsThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
