Managing Severe Allergic Reactions in Emergency Department

Introduction:

A severe allergic condition, also called anaphylaxis, occurs within a few seconds or minutes or rarely hours and requires immediate treatment. Most of the allergies are due to drugs, venom, or food. When the symptoms of allergic reactions are severe and block the airways, the individual should seek emergency treatment. The treatment for these allergic reactions depends on the severity of the condition. The initial step includes intramuscular epinephrine injection followed by corticosteroids and intravenous antihistamines.

What Is a Severe Allergic Condition?

A severe allergic condition or anaphylaxis is a condition that has a sudden onset and can involve many organs. This reaction causes the release of several chemicals, which can cause shock, decreased blood pressure, and breathing difficulty by narrowing the airways.

What Are the Symptoms of a Severe Allergic Condition?

The symptoms of severe allergic reactions are:

• Skin reactions such as rashes, hives (urticaria, which are raised rashes), and itching.

• Pale skin.

• Angioedema (swelling of the skin).

• Hypotension (decreased blood pressure).

• Narrowing of airways.

• Swelling of the throat and tongue, which causes difficulty in breathing along with wheezing.

• Dizziness.

• Rapid pulse rate.

• Nausea.

• Vomiting.

• Diarrhea.

What Is the Pathophysiology of Anaphylaxis?

Anaphylaxis is triggered by the direct or indirect activation of the mast cells (a form of white blood cell which acts as a first line of defense), which releases chemical mediators. IgE-mediated anaphylaxis occurs when FcεRI (Fc epsilon RI, a high-affinity IgE receptor) is activated, which causes degranulation of mast cells and cross-linking of IgE molecules. Non-IgE-mediated anaphylaxis can also occur. IgG antibodies can also be involved.

How Is Anaphylaxis Classified?

According to Ring and Messmer, anaphylaxis is classified into 4 stages which are:

• The first stage includes skin lesions and increased temperature of the body.

• The second stage includes cardiovascular reactions such as increased heart rate called tachycardia and decreased blood pressure called hypotension.

• The third stage includes shock and spasms of smooth muscles such as the uterus and bronchi (part of the lung that passes the air).

• The fourth stage includes cardiac arrest (stoppage of the functions of the heart).

What Are the Common Trigger Factors of a Severe Allergic Condition?

The trigger factors of severe allergic conditions are:

• Milk and egg are the most common trigger factors in children.

• Peanuts, fish, wheat, sesame, tree nuts, shellfish, and soy.

• Insect, bee, or wasp venoms.

• Drugs in children mostly occur due to antibiotics and analgesics, and beta-lactam antibiotics are the most common. In adults, nonsteroidal anti-inflammatory drugs (NSAIDs) like Aspirin are common triggers.

• Imaging tests that use intravenous (IV) contrast.

• Latex.

• Rarely less intense physical activity such as jogging or walking can also trigger an allergic reaction.

What Are the Risk Factors for a Severe Allergic Condition?

The risk factors for severe allergic conditions are:

• Previous anaphylaxis: a past history of anaphylaxis can increase the severity of allergic reactions.

• Certain drugs, such as ACE inhibitors or beta-blockers (cardiovascular drugs), and nonsteroidal anti-inflammatory drugs (NSAIDs) like Aspirin.

• Mastocytosis, a genetic disorder in which the mast cells grow abnormally that causes allergic symptoms and can also increase the severity.

• Increased serum tryptase levels.

• Allergic asthma.

• Alcohol and illegal drug abuse.

• Sex hormones also play an important role; males are more commonly affected.

What Is the Diagnosis of a Severe Allergic Condition?

The diagnosis primarily depends on the clinical manifestations, which is the sudden onset and involvement of many organs. The organs which can be affected are the cardiovascular system, respiratory system, gastrointestinal system, mucosa, or skin (most common). Tests such as measuring IgE can help in identifying allergic triggers. Prick testing or provocation testing is done to identify specific allergens in which fine amounts of allergens like food or drugs are given.

How to Manage Severe Allergic Reactions in Emergency Department?

After the diagnosis, the differential diagnoses should be ruled out and the treatment should be started immediately. The management includes:

1. The first line of therapy includes intramuscular administration of Epinephrine. The starting dose of Epinephrine should be 0.01 ml/kg (milliliter per kilogram) body weight, and the maximum dose that can be administered is up to 0.5 milligrams.

2. If the cardiovascular system is not stabilized, intravenous administration of Epinephrin should be considered.

3. Supportive management, such as fluid replacement and oxygen, should be given. If it is practicable, the allergen should be removed.

4. In case of difficulty in breathing and stridor (abnormal breathing sound), short-acting β-2 agonists such as Albuterol should be given.

5. Antihistamine drugs such as 4 mg Dimetindene maleate can provide relief from cutaneous symptoms. Corticosteroids such as 250 mg of Prednisolone are also given. Oral administration of corticosteroids and antihistamines are given in case of sever urticaria.

6. In case of respiratory distress, the patient should be positioned upright. In case of a circulatory problem, the patient's legs should be elevated to improve blood circulation. In the case of pregnant patients, legs should be elevated and positioned on the left side. The lateral recumbent position (patient lying on the right or left side) is preferred in the case of unconscious patients.

7. The cardiac system and respiratory systems should be monitored. In case of difficulty breathing, at least 6 to 8 hours should be monitored.

Preventive measures should be taken, such as:

• Subcutaneous specific immunotherapy (SCIT) in the case of children who are allergic to wasp or bee venom.

• The patient should be educated about dietary intake and avoid possible allergens.

• An allergic ID card should be provided to patients who are allergic to certain drugs.

• The patients should carry an emergency allergy kit which should contain an Epinephrine autoinjector(the dosage should be 0.15 milligrams in the case of children who are below 30 kilograms and 0.3 milligrams in the case of adults), two tablets of Cetirizine which is an antihistamine, and two tablets of Prednisolone 50 milligrams. If the patient has difficulty in breathing, a Salbutamol inhaler which is a β-2 receptor agonist, should be in the kit.

Conclusion:

A severe allergic reaction, also called anaphylaxis, is the most common condition for emergency treatment. When the patient is presented to the hospital, the diagnosis is made, the differential diagnosis should be ruled out, and appropriate measurements should be taken. The patient should be educated about allergies and should carry an allergic ID card to prevent future allergic reactions.