What to do if you have severe allergies?

This is the 3301st article of Da Yi Xiao Hu

Speaking of allergies, I believe everyone is familiar with them. In our daily lives, the first thing that comes to your mind is pollen? Seafood? Cephalexin? Ultraviolet rays... Yes, there are a thousand allergens for a thousand people. So, are allergies really just like the common skin itching, erythema, wheals? Sneezing? In fact, it is not. In severe cases, breathing difficulties, even shock and death may occur. Today, let's go into the "First Aid Guide for Severe Allergic Reactions" and see what the experts say?

1. What is a severe allergy?

Severe allergic reaction refers to a sudden, severe, life-threatening systemic allergic reaction after the body comes into contact with an allergen. Its main clinical features are the rapid onset of life-threatening respiratory and/or circulatory system problems, and in most cases, skin and mucosal system symptoms.

2. How to diagnose severe allergies?

1. Rash or itching alone does not constitute a severe allergic reaction. The diagnosis of severe allergic reactions should use the diagnostic criteria listed in Table 1, and attention should be paid to the fact that patients may have strange and atypical symptoms.

Table 1 Diagnostic criteria for severe allergic reactions

Table 2 Grading criteria for severe allergic reactions

3. What should I do if severe allergies occur?

If a patient has a suspected severe allergic reaction, he/she should call the emergency number or be sent to a nearby hospital immediately, and seek help from medical workers on site or nearby. Before the arrival of medical workers, the patient should be separated from the allergen as quickly as possible and lie flat. If vomiting occurs, the head should be tilted to one side and foreign objects should be removed to prevent suffocation caused by aspiration of vomitus. Epinephrine injection should be available in pre-hospital and in-hospital emergency equipment.

4. How to use epinephrine correctly in rescue?

1. Timing of medication

For patients with severe allergic reactions of grade II or above, epinephrine is the first choice of treatment and should be used as early as possible.

2. Route of administration

Subcutaneous injection of epinephrine is not recommended for emergency treatment of severe allergic reactions. For patients with grade II and III reactions, intramuscular injection of epinephrine should be the first choice; intramuscular injection of epinephrine can also be considered for patients with grade I reactions whose gastrointestinal symptoms are difficult to relieve. The site for intramuscular injection of epinephrine is the outer side of the middle thigh. For patients with grade IV reactions who have experienced or are about to experience cardiac and/or respiratory arrest, epinephrine should be injected intravenously; for patients with grade III reactions who have established intravenous access and are monitored in the ICU/during surgery, epinephrine can be injected intravenously. For patients with grade II and III reactions, intravenous drip of epinephrine can be used after 2-3 intravenous/intramuscular injections of epinephrine, or after intravenous access has been established and monitored in the ICU/during surgery; for patients with grade IV reactions, intravenous drip of epinephrine can be considered when symptoms improve but are not completely relieved.

3. Intramuscular injection dosage and concentration?

1) Dosage: Epinephrine is administered at 0.01 mg/kg body weight. The maximum single dose for patients aged 14 years and above is not more than 0.5 mg, and the maximum single dose for patients under 14 years old is not more than 0.3 mg;

2) Concentration: 1mg/mL (1:1000), equivalent to the concentration of 1mL:1mg epinephrine injection; if the effect is not satisfactory after 5-15 minutes, the dose can be repeated.

4. Intravenous dosage and concentration?

1) Dosage: Grade III reaction: 0.1-0.2 mg for children over 14 years old and adults, 2-10 μg/kg for children ≤14 years old; Grade IV: 0.5-1 mg for children over 14 years old and adults, 0.01-0.02 mg/kg for children ≤14 years old

2) Concentration: 0.1 mg/mL (1:10000), that is, dilute the existing 1 mL:1 mg epinephrine injection solution 10 times; if the effect is not ideal after 3-5 minutes, the dose can be repeated.

5. Intravenous drip dosage and concentration?

1) Dosage: 3-20 μg/(kg·h)

2) Concentration: 0.1-0.004 mg/mL (1:10000-1:250000), i.e. diluting the existing 1mL:1mg epinephrine injection by 10-250 times.

6. What are the contraindications for the use of epinephrine?

There are no absolute contraindications to the use of epinephrine in the emergency treatment of life-threatening severe allergic reactions; however, it should be used with caution in patients with a history of cardiovascular disease and elderly patients, weighing the pros and cons.

7. How to deal with adverse reactions to adrenaline?

To prevent adverse reactions caused by the use of adrenaline, unnecessary intravenous administration should be avoided as much as possible; when using adrenaline intravenously, attention should be paid to controlling the concentration and continuous monitoring of the heart, blood pressure, respiration, and blood oxygen saturation. When local adverse reactions to adrenaline occur, phentolamine can be used for local infiltration injection.

5. What else should you pay attention to when rescuing severe allergic reactions?

1. Epinephrine injection should be available in pre-hospital and in-hospital emergency equipment.

2. During the treatment of severe allergic reactions, the heart, blood pressure, respiration, and blood oxygen saturation should be closely monitored.

3. For patients with severe allergic reactions, when airway edema or bronchospasm occurs and causes severe breathing difficulties, endotracheal intubation or tracheotomy should be considered. In emergency situations, cricothyroid membrane puncture can be performed on adults.

4. Antihistamines (such as diphenhydramine, chlorpheniramine), glucocorticoids (such as dexamethasone), and β2 receptor agonists (bronchodilators such as salbutamol) are only second-line medications for severe allergic reactions.

5. Fluid resuscitation can be used for patients with severe allergic reactions and unstable circulatory system. The fluid dosage is generally 20 ml/kg, and the dose is adjusted according to the patient's condition.

6. How to prevent severe allergic reactions?

1. To avoid allergic reactions, it is crucial to avoid contact with and eliminate allergenic factors.

2. All patients with severe allergic reactions should continue to be closely observed after treatment until the symptoms completely disappear.

3. All patients with severe allergic reactions should receive education about anaphylaxis, risk of recurrence, avoidance of triggers, self-injection of epinephrine (epinephrine pen), and seeking further treatment, and should be referred to an allergist for follow-up evaluation.

Emergency Department, The Second Affiliated Hospital of Xi'an Jiaotong University

Edited by Zhang Li, head nurse

Emergency Department, The Second Affiliated Hospital of Xi'an Jiaotong University

Reviewed by Chief Physician Pei Honghong

Note: Tribute to the original author, the copyright belongs to the original author.

Original citation information: Li Xiaotong, Zhai Suodi, Wang Qiang…Recommendations of the “Guidelines for First Aid in Severe Allergic Reactions”[J]. Journal of Adverse Drug Reactions,