Anaphylaxis Requires Prompt Epinephrine Shot

Patients with signs of anaphylaxis should be given epinephrine in the anterolateral thigh as first-line treatment, according to new practice parameters published in the December issue of the Annals of Allergy, Asthma and Immunology.

However, studies show that even when anaphylaxis is correctly diagnosed, clinicians in emergency departments fail to administer epinephrine up to 80% of the time. Further, clinicians misdiagnose as many as 57% of ED patients presenting with anaphylaxis, the authors report.

Lead author Ronna L. Campbell, MD, PhD, from the Department of Emergency Medicine, Mayo Clinic, Rochester, Minnesota, is part of a Joint Task Force on Practice Parameters, which represents the American Academy of Allergy, Asthma and Immunology; the American College of Allergy, Asthma and Immunology (ACAAI); and the Joint Council of Allergy Asthma and Immunology.

“Since emergency department physicians are often the first to see patients who are suffering from anaphylaxis, it’s especially important that they not only correctly diagnose the problem, but understand that epinephrine should be administered as soon as possible,” Dr Campbell said in a news release from the ACAAI. “In addition, following a severe, allergic reaction, patients should be referred to an allergist, as allergists provide the most comprehensive follow-up care and guidance.”

Anaphylaxis symptoms can progress quickly, over minutes to hours, the authors report. Fatal food anaphylaxis can progress to respiratory and cardiac arrest in a median time of 30 minutes, insect venom-induced anaphylaxis has a median time of 15 minutes to arrest, and medication-induced anaphylaxis in a hospital setting has a median time of 5 minutes to arrest.

Studies of fatal and near-fatal anaphylaxis show that most patients had no history of severe allergic reaction.

Complications of epinephrine administration are very rare, the authors write. Further, the report states, “there are no absolute contraindications for the administration of epinephrine in the setting of anaphylaxis.”

Anaphylaxis is very likely if any one of three criteria is fulfilled:
· acute onset of illness (minutes to hours), with involvement of skin and/or mucosa, such as pruritus, flushing, hives, angioedema accompanied by either respiratory compromise or falling blood pressure, or end-organ dysfunction;

· two or more of the following symptoms occurring rapidly after exposure to likely allergen, including involvement of skin and/or mucosa; signs of respiratory compromise such as dyspnea, wheeze, falling peak expiratory flow, stridor, or hypoxemia; falling blood pressure or end-organ dysfunction; persistent gastrointestinal symptoms such as vomiting, crampy abdominal pain, or diarrhea; and

· falling blood pressure within minutes to several hours of exposure to a known allergen.

The practice parameters also advise the following:

· Do not rely solely on the presence of shock for the diagnosis of anaphylaxis, as there is a wide range of clinical presentations.

· Triage patients with suspected anaphylaxis carefully and quickly, and prepare to administer epinephrine.

· Place patients in a supine position, or on their left side if they are pregnant.

· Administer oxygen to patients with respiratory or cardiac symptoms and consider oxygen administration for all patients with anaphylaxis, regardless of their respiratory condition.

· Determine whether a patient is at risk for severe and potentially fatal anaphylaxis when making treatment decisions.

· Administer epinephrine intramuscularly in the anterolateral thigh immediately after diagnosing anaphylaxis. Patients who do not respond to treatment may need intravenous epinephrine. Administer intraosseous epinephrine if intravenous access is not possible.

· Do not give antihistamines or corticosteroids in place of epinephrine.

· Prepare for airway management and possibly intubation for signs of airway edema or respiratory compromise.

· Patients with circulatory collapse require a large volume of intravenous or intraosseous normal saline through large-bore catheters.

“Strongly consider observing patients who have experienced anaphylaxis for at least 4 to 8 hours,” or longer for those with a history of risk factors for severe anaphylaxis, the authors write.