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Flashcards in Anaphylaxis Deck (13):

What is anaphylaxis?

Anaphylaxis is a potentially fatal allergic reaction to a foreign substance known as an antigen

the onset is rapit (~15 min for an insect sting and ~30 min for food ingestion)

the reaction is systemic and primarily involves the skin, respiratory system, CV, and GI Systems.


Anaphylaxis is a type __________ hypersensitivity

what are the stages to developing this type of reaction?

Anaphylaxis is IgE mediaged - Type I hypersensitivity

During the sensitization stage the pt is asymptomatic but the body is developing antibodies (after the first exposure)

Subsequent exposures lead to an anaphylatic response: crosslinking of the IgE leads to the degranulation of basophils and mast cells


What is an anaphylactoid reaction?

an anaphylactoid reaction is not IgE mediated and is the result of direct breakdown of mast cell and basophil membranes

anaphylactoid reactions can occur after a first time exposure 

and treatment is the same as for anaphylactic reactions


Substances that can cause an anaphylactoid reaction include: 

Radiopaque contrast media (CT contrast, iv flourescein)


opioid narcotics



Neuromuscular blocking agents

exercise (this is why I don't do it)

exposure to cold



What are the clinical manifestations for anaphylaxis?


Upper respiratory

Lower respiratory

pts with what types of underlying conditions are at an increased risk of death?

  1. Skin
    1. Flushing, puritis, urticaria, angioedema
  2. Upper respiratory
    1. edema of larynx, epiglottis, lips, tongue
    2. dysphonia, congestion, rhinorrhea, sneezing, itchy eyes, tearing of eyes, fonjunctival injection, stridor, metallic taste
  3. Lower respiratory
    1. bronchospasm, throat tightness, chest tightness, hoarseness, wheezing, SOB, cough, hypoxia, asphyxia death

**pts with underlying lung disease are at an increased risk of death


Acute treatment of Anaphylaxis

Airway Constriction

Airway Constriction

  1. Laryngeal Edema/Broncospasm
    1. Epinephrine (IM)
    2. Nebulized bronchodilator
    3. Oxygen
  2. Airflow blockage
    1. intubation
    2. tracheostomy


What is a Uniphasic reaction?

a Biphasic reaction?

Protraced anaphylaxis

Uniphasic is the most common- the patient has a reaction which resolves after 4 hours

Biphasic- the reaction comes back within 12 hours without exposure to a second antigen

Protracted- the reaction last hours to days.  Weeks even!

delayed- begins hours after exposure


**Pt with uncontrolled s/s after 1+ hour should be admitted to the hospital overnight 


What are the three criteria for anaphylaxis?

Criteria for diagnosing anaphylaxis

1. Acute onset of illness that involves the skin or mucosa AND hypotension or end organ sysem dysfunction

2. Rapid onset of s/s (see chart) after exposure to a likely antigen 

3. Rapid onset of hypotension after exposure to a known allergen


Anaphylaxis treatment for 



  1. Hypotension:
    1. trendelenburg position
    2. epinephrine
    3. volume expanders 
    4. oxygen


**If the pt is epinephrine resistant (because they are on a beta blocker)  use Glucagon and vasopressin


Acute treatment of Anaphylaxis


give 25-50 mg IV or IM of diphenhydramine (Benadryl)

Treat Urticaria with 

H1R and H2R antihistamines


What is the first line treatment for anaphylaxis?

What is the dose?

what if the patient doesn't respond after 3 doses?

Epinephrine given IM in the anterolateral thigh is the first line treatment for anaphylaxis

There are no contraindications for giving epi in t he case of anaphylaxis

Dose: Adults 1mg/mL every 5-15 minutes (0.3-0.5 mg)

If the patient doesn't respond after 3 doses switch to an IV or an IO 


What is the proper adult dose for Ratinidine? 

Given with diphenhydromine only

50 mg IV


What is the proper adult dose for 


125 mg IV