2
Diagnosis
Key Points
Î The definition of anaphylaxis has, to this date, eluded precision.
Î In 2006, experts on anaphylaxis concluded that there were 3
presentations consistent with anaphylaxis:
1. an acute onset of a reaction that included the skin and/or mucosal tissue and
involvement of the respiratory tract and/or a decrease in blood pressure
2. the rapid onset of a reaction after exposure to a likely allergen that involved 2
organ systems (respiratory tract, skin, decrease in blood pressure, and/or persistent
gastrointestinal symptoms); or
3. a decrease in blood pressure alone after exposure to a known allergen.
Î Despite the apparent success of these definitions of anaphylaxis,
identification of patients who present with atypical anaphylaxis
remains a problem.
> The National Institute of Allerg y and Infectious Diseases/Food Allerg y and
Anaphylaxis Network criteria yield a sensitivity of 96.7% and a specificity of
82.4% giving a positive predictive value of 68.6% and a negative predictive value of
98.4%. (Campbell RL et al. JACI 2012; 129(3):748-752.)
Î The underuse of epinephrine in the treatment of anaphylaxis is to
some degree understandable if the correct diagnosis is not made.
Î Better recognition of atypical or unusual presentations of anaphylaxis
should intuitively lead to greater use of epinephrine and perhaps even
a decrease in anaphylactic morbidity and mortality.
Î Patients in anaphylaxis can develop cardiac manifestations
1. secondary to respiratory compromise or hypotension
2. as a direct effect of treatment with epinephrine or vasopressors, and/or
3. owing to vasoactive mediator release from mast cells in the heart.
Î Therefore, it should not be surprising that anaphylaxis can present
with prominent cardiac symptoms, such as chest pain in children and
adults, electrocardiographic changes, and even myocardial damage.
Î Abdominal symptoms can also be present as a manifestation of
anaphylaxis. These may include nausea, vomiting, diarrhea, and
cramping abdominal pain.
