Therapeutic controversies in the management of acute anaphylaxis.

At present there are few controlled clinical therapeutic trials in acute anaphylaxis despite the emergence of evidence based medicine. Moreover, the explosive nature, unpredictable onset, and usually rapid response to treatment that characterise acute anaphylaxis mean that this situation is unlikely to change.' The vast majority of serious anaphylactic reactions occur unexpectedly,2 typically in fit patients. Anaphylaxis is rarely seen or described in critically ill or shocked patients other than in those with asthma.1 Therefore, treatment recommendations have to be based on clinical observation, interpretation of the pathophysiology and, to an extent, animal studies.' However, descriptions of the management of anaphylaxis, for instance those in Hospital Update in 19914 and on angio-oedema in the British Medical Journal in 1992,5 are often then criticised for the treatment recommended.9 A recent expert opinion by Fisher on the treatment of acute anaphylaxis" was followed by no less than 10 letters in response, many of which contained errors of logic as pointed out by Fisher in replying to them." Clearly there is confusion about the correct management of acute anaphylaxis. Much of the controversy is due to misinterpretation of published reports. In this review I reassess the role, route of delivery, dose, concentration, and efficacy of the various drugs used in anaphylaxis. Adrenaline, steroids, antihistamines, fluids, glucagon, aminophylline, and discharge drugs will be discussed in detail. I shall use the term "anaphylaxis" to refer to both anaphylactic reactions (IgE mediated immediate type hypersensitivity reactions) and anaphylactoid reactions (non-immunologically triggered), as the clinical expression and final mediators involved are identical.'2 Tables are included giving clear recommendations for first line, second line, and discharge treatment, and allowing rapid evaluation of the drugs involved. Adrenaline