Chapter 21: Allergy and Anaphylaxis

Allergy-related emergencies may involve

a. Acute airway obstruction

b. Cardiovascular collapse

Chemicals that are released into the immune system in a response

histamines and leukotrienes

An allergic reaction may be

a. Mild and local, characterized by itching, redness, and tenderness

b. Severe and systemic—a condition known as anaphylaxis

Three common signs

a. Urticaria (hives)

b. Angioedema

c. Wheezing

stridor

may be heard on inspiration if there is upper airway narrowing

hypotension

due to vasodilation may occur, as well as increased capillary permeability.

Anaphylaxis

is an extreme, life-threatening allergic reaction.

Food

a. Certain foods (eg, shellfish, peanuts) may be the most common trigger of anaphylaxis.

b. Symptoms:

i. May take more than 30 minutes to appear

ii. May not include the presence of skin signs (eg, hives)

iii. Abdominal cramping, vomiting, and diarrhea are common.

iv. The reaction can be severe and involve the respiratory and/or cardiovascular systems

Medication

a. The second most common source of anaphylactic reactions

i. Antibiotics

ii. Nonsteroidal anti-inflammatory agents

b. If the medication is injected, the reaction may be immediate (within 30 minutes) and severe.

c. Reactions to oral medications may take more than 30 minutes to appear, but can also be very severe.

Plants

a. Dusts, pollens, and other plant materials can cause a rapid and severe allergic reaction.

b. Common plant allergens include ragweed, ryegrass, maple, and oak.

Chemicals

a. Certain chemicals, makeup, soap, hair dye, latex, and various other substances can cause severe allergic reactions.

b. Latex is of particular concern to health care providers.

i. Use latex alternatives such as nitrile gloves.

Envenomation

the process of an insect injecting its venom

The stinging organ

of most insects is a small, hollow spine projecting from the abdomen.

Honeybees

cannot withdraw their stinger.

Wasps and hornets

can sting multiple times.

Some ants, especially fire ants

strike repeatedly

Insect stings signs and symptoms

a. Sudden pain

b. Swelling

c. Localized heat

d. Widespread urticaria

e. Redness in light-skinned individuals

f. Itching and possibly a wheal (raised, swollen, well-defined area on the skin)

g. As long as these manifestations remain localized, they are not usually serious.

anaphylaxis may experience

a. Stridor

b. Bronchospasm and wheezing

c. Chest tightness and coughing

d. Dyspnea

e. Anxiety

f. Gastrointestinal complaints

g Hypotension

h. Occasionally, respiratory failure

i. If untreated, an anaphylactic reaction can proceed rapidly to death.

j. More than two-thirds of patients who die of anaphylaxis do so within the first 30 minutes.

Allergic reactions may present

may present as respiratory or cardiovascular distress in the form of shock.

If the patient is anxious and in distress

immediately call for ALS backup if available.

Airway and breathing

a. Anaphylaxis can cause rapid swelling of the upper airway.

b. Not all allergic reactions are anaphylactic reactions.

c. Quickly assess for increased work of breathing, use of accessory muscles, head bobbing, tripod positioning, nostril flaring, and abnormal breath sounds.

d. Assist the patient into a comfortable position to maximize ventilations.

e. If signs of shock emerge, immediately place the patient in the supine position as tolerated.

f. Initiate high-flow oxygen therapy or assist ventilations as necessary.

Circulation

a. Some patients in anaphylaxis may present with signs and symptoms of circulatory distress, such as hypotension.

b. Assess for signs of hypoperfusion.

c. Treat for shock.

d. The definitive treatment for anaphylactic shock is epinephrine.

Transport decision

a. If anaphylaxis is suspected, or if a relatively mild allergic reaction appears to be worsening, immediate transport is warranted.

b. If the patient is calm and does not exhibit severe symptoms, consider continuing the assessment, but error on the side of emergency transport.

History taking

i. Have any interventions already been completed?

ii. Has the patient experienced a severe allergic reaction in the past?

3. Be alert for any statements regarding the ingestion of foods that commonly cause allergic reactions.

4. Inquire about the presence of gastrointestinal complaints such as nausea and vomiting.

Epinephrine

is a sympathomimetic hormone.

a. It mimics the sympathetic (fight-or-flight) response.

2. Causes the blood vessels to constrict, which reverses vasodilation and hypotension

3. Other properties of epinephrine increase cardiac contractility and relieve bronchospasm in the lungs.

4. It can rapidly reverse the effects of anaphylaxis.

Epinephrine side effects

a. High blood pressure

b. Increased pulse rate

c. Anxiety

d. Cardiac arrhythmias

e. Pallor

f. Dizziness

g. Chest pain

h. Headache

i. Nausea

j. Vomiting

Patients who do not have signs of respiratory compromise or hypotension and who do not meet the criteria for a diagnosis of anaphylaxis should not be given

epinephrine