Recommendations for the treatment of acute anaphylactic reactions

A study published in a recent issue of the Medical Journal of Australia has offered clear and comprehensive recommendations for the management of anaphylaxis. Along with other studies, researchers have noted the increase in incidence of allergic disease, triggering attempts to develop guidelines to be applied in emergency department and community settings for these disorders. The first line of treatment for anaphylaxis continues to be intramuscular adrenaline and fluid resuscitation as required. Follow up after the acute reaction and specialist referral is essential to prevent recurrence.

Anaphylaxis is an uncommon but potentially life-threatening reaction due to associated upper airway obstruction, bronchospasm and/or hypotensive effects. Along with other allergic diseases, the prevalence of anaphylaxis has increased over recent decades. This highlights the importance of having clear evidence based guidelines for the management of acute anaphylaxis within the community. An article published in the September 2006 issue of the Medical Journal of Australia, Allergy Practice Essentials pooled current available evidence to provide a structured review on anaphylaxis. In particular, they presented guidelines for the diagnosis of anaphylaxis and appropriate acute and follow-up management for the condition. This is invaluable information for both primary care and emergency physicians. Researchers noted that despite the severity of this condition, there is currently no universally accepted definition of anaphylaxis. This has limited research in the field and has lead to failures in the diagnosis and timely treatment of the condition. However, it is generally accepted that anaphylaxis is a severe, generalised, hypersensitivity reaction affecting the cardiovascular and respiratory systems as well as other systems such as the skin and gastrointestinal tract. Food, insect venoms or medications trigger the majority of reactions by activating mast cells to release histamine and numerous cytokines. This causes a cascade of effects in the body including vasodilation, extravasation of fluid, smooth muscle contraction and mucosal secretions. Due to the lack of diagnostic criteria and reliable investigations, anaphylaxis must be suspected on clinical grounds. Anaphylactic reactions in children are most commonly triggered by foods and produce predominantly respiratory symptoms. Venom and drug-induced reactions are more frequently seen in adults and characteristically produce cardiovascular and cutaneous symptoms. All medical practitioners should be equipped with knowledge of the common presentations and differentials of these reactions. Current research suggests the first-line treatment of anaphylaxis should involve placing the patient in a supine position (unless vomiting) and giving an immediate dose of intramuscular adrenaline (0.01 mg/kg to a maximum dose of 0.5 mg) into the lateral thigh. There is no evidence to support the use of ancillary medications such as antihistamines or steroids in acute management. If the patient is hypotensive a bolus dose of 20 mL/kg of normal saline should be administered intravenously. If the above measures fail, an intravenous infusion of adrenaline (according to hospital guidelines) or repeated intramuscular doses every 3-5 minutes may be instituted. Patients should then be monitored for at least four hours. Long-term management is essential due to the unpredictable nature of the condition. All patients should be referred to an appropriate allergy specialist and receive advice regarding trigger avoidance, dangerous medications and identifying warning signs. An anaphylaxis action plan should be devised including how to use an EpiPen. Specialist bodies recommend EpiPen Junior (0.15mg) for patients weighing 10-20 kg and EpiPen (0.3 mg) for patients weighing over 20 kg. In addition, patients should be fitted with medical alert bracelets. This article therefore provided a simple and structured approach to the management of anaphylaxis that can be applied in clinical practice. If the summarised guidelines listed above are followed, the morbidity and mortality of anaphylaxis can hopefully be reduced. Further research is required into the mechanisms for the increase in incidence of the disorder and appropriate modes of prevention. Source:Brown S, Mullins R & Gold M. Anaphylaxis: diagnosis and management, Med J Aust 2006; 185: 283-289.