Anaphylaxis: Acute treatment and management

Anaphylaxis is the maximal variant of an acute life-threatening immediate-type allergy. Due to its often dramatic onset and clinical course, practical knowledge in the management of these reactions is mandatory both for physicians and patients. It has to be distinguished between acute treatment modalities and general recommendations for management of patients who have suffered from an anaphylactic reaction. Acute treatment comprises general procedures like positioning, applying an intravenous catheter, call for help, comfort of the patient as well as the application of medication. The acute treatment modalities are selected depending upon the intensity of the clinical symptomatology as they are categorized in 'severity grades'. First of all it is important to diagnose anaphylaxis early and consider several differential diagnoses. This diagnosis is purely clinical and laboratory tests are of no help in the acute situation. Epinephrine is the essential antianaphylactic drug in the pharmacologic treatment. It should be first applied intramuscularly, only in very severe cases or under conditions of surgical interventions intravenous application can be tried. Furthermore, glucocorticosteroids are given in order to prevent protracted or biphasic courses of anaphylaxis; they are of little help in the acute treatment. Epinephrine autoinjectors can be used by the patient him/herself. Histamine H₁-antagonists are valuable in mild anaphylactic reactions; they should be given intravenously if possible. The replacement of volume is crucial in antianaphylactic treatment. Crystalloids can be used in the beginning, in severe shock colloid volume substitutes have to be applied. Patients suffering from an anaphylactic episode should be observed over a period of 4-10 h according to the severity of the symptomatology. It is crucial to be aware or recognize risk patients as for example patients with severe uncontrolled asthma, or under β-adrenergic blockade. When bronchial symptoms are in the focus, inhaled β₂-agonists can be tried, also for laryngeal edema. The use of combined H₁- and H ₂-antagonists has been recommended for prophylaxis prior to application of potentially anaphylaxis-eliciting drugs (e.g. radiographic contrast media). Patients who have survived an anaphylactic reaction have to be thoroughly examined and an allergy diagnosis has to be performed with regard to the eliciting agent and the pathogenic mechanism involved. In cases of clear-cut IgE-mediated anaphylaxis, allergen-specific immunotherapy is available for some allergens and helpful as for example for insect venom anaphylaxis. Furthermore, patients should be trained with regard to the nature of anaphylaxis, the major eliciting agents and the principles of behavior and coping with the situation including the handling of epinephrine autoinjectors and the application of antianaphylactic medication. Educational programs for anaphylaxis have been developed.