Anaphylaxis, Acute Allergic Reactions, and

Angioedema

ANAPHYLAXIS AND ALLERGIC REACTIONS

Clinical Features

Majority: signs and symptoms begin suddenly, often within 60 minutes of exposure

biphasic phenomenon 3-20% of patients caused by a second phase of mediator release,

peaking 4-8 hours after the initial exposure and exhibiting itself clinically 3-4 hours after the initial clinical manifestations have cleared

late-phase allergic reaction primarily mediated by the release of newly generated

cysteinyl leukotrienes, the former slow-reacting substance of anaphylaxis

Diagnosis

Serum tryptase levels

Treatment

Treatment

Treatment

Disposition and Follow-Up

Admission/DischargeAdmission to hospital is rareAll unstable patients with anaphylaxis refractory

to treatment or where airway interventions were required should be admitted to the intensive care unit.

Patients who receive epinephrine should be observed in the ED, but the duration of observation is based on experience rather than clear evidence.

Disposition and Follow-Up

Admission/DischargeIf patients remain symptom free after

appropriate treatment following 4 hours of observation, the patient can be safely discharged home.

prolonged observation periods should be considered in patients with a past history of severe reaction and those using -blockers

Disposition and Follow-Up

URTICARIA AND ANGIOEDEMA

Urticaria

Treatment of urticarial reactions is generally supportive and symptomatic, with attempts to identify and remove the offending agent.

Antihistamines, with or without corticosteroids, are usually sufficient, although epinephrine can be considered in severe or refractory cases.

The addition of a histamine-2 receptor blocker, such as ranitidine, may also be useful in more severe, chronic, or unresponsive cases.

Angioedema

Angioedema of the tongue, lips, and face has the potential for airway obstruction.

Management is supportive, with special attention to the airway, which can become occluded rapidly and unpredictably.

Epinephrine, antihistamines, and steroids are often still used, but benefits have not been clearly demonstrated.

Angioedema

Patients with mild swelling and no evidence of airway obstruction can be observed in the ED and discharged if swelling diminishes.

Patients with moderate to severe swelling, dysphagia, or respiratory distress are best admitted for close observation.

Take home message

ANY QUESTION?