Allergic Reactions

Question 1

anaphylaxis mechanisms

Answer 1

Immunologic
In the immunologic mechanism, immunoglobulin E (IgE) binds to the antigen (the foreign material that provokes the allergic reaction). Antigen-bound IgE then activates FcεRI receptors on mast cells and basophils. This leads to the release of inflammatory mediators such as histamine. These mediators subsequently increase the contraction of bronchial smooth muscles, trigger vasodilation, increase the leakage of fluid from blood vessels, and cause heart muscle depression. There is also an immunologic mechanism that does not rely on IgE, but it is not known if this occurs in humans.

Non-immunologic
Non-immunologic mechanisms involved substances that directly cause the degranulation of mast cells and basophils. These include agents such as contrast medium, opioids, temperature (hot or cold), and vibration.

Question 2

humoral immunity

Answer 2

(also called the antibody-mediated system) is the aspect of immunity that is mediated by macromolecules (as opposed to cell-mediated immunity) found in extracellular fluids such as secreted antibodies, complement proteins and certain antimicrobial peptides. Humoral immunity is so named because it involves substances found in the humours, or body fluids.

Question 3

cell mediated immunity

Answer 3

Cell-mediated immunity is directed primarily at microbes that survive in phagocytes and microbes that infect non-phagocytic cells. It is most effective in removing virus-infected cells, but also participates in defending against fungi, protozoans, cancers, and intracellular bacteria. It also plays a major role in transplant rejection.

immune response that does not involve antibodies but rather involves the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen. Historically, the immune system was separated into two branches: humoral immunity, for which the protective function of immunization could be found in the humor (cell-free bodily fluid or serum) and cellular immunity, for which the protective function of immunization was associated with cells. CD4 cells or helper T cells provide protection against different pathogens. Cytotoxic T cells cause death by apoptosis without using cytokines, therefore in cell mediated immunity cytokines are not always present.

Question 4

ALLERGEN

Answer 4

substance causing an exaggerated immune response

Question 5

ANAPHYLAXIS

Answer 5

Exaggerated immune response

allergen binds to IgE
IgE binds to mast cell
mast cell degranulation
release histamine

Question 6

effects of histamine (H1 and H2 receptors)

Answer 6

inflammation - swelling
bronchconstriction
vasodilatation

Question 7

histamine

Answer 7

released by body in anaphylaxis

• contraction of bronchial smooth muscles,
• stimulation of vascular permeability, and

Question 8

leukotiene

Answer 8

other chemical released by the body in anaphylaxis

They exhibit a number of biological effects such as - contraction of bronchial smooth muscles,

• stimulation of vascular permeability, and
• attraction and activation of leukocytes.

Compared to histamine, which causes constriction of airways and edema formation, the leukotrienes are three to four orders of magnitude more potent and the effects have longer duration

Question 9

H1 RECEPTORs on our lungs cause

Answer 9

When stimulated it causes bronchoconstriction

Question 10

What effect H2 RECEPTORs have on our GI tract & Blood Vessels

Answer 10

Throwing up or Diarrehea - on the blood vessels they dilate

Question 11

What position should a patient having an allergic Rx be in?

Answer 11

lay them flat

Question 12

What drug is a histamine blocker

Answer 12

benedryl

Question 13

Dosage of epinephrine

Answer 13

epinephriene
adult 0.3mg pedi 0.15mg

bronchodialator
vasoconstrictor

Question 14

name 2 of the allergens

Answer 14

ant, bee, shellfish, peanuts….. Common allergens

Question 15

sound a patient having anaphylaxis might make

Answer 15

wheezing

Question 16

adult dose epi

Answer 16

.3mg

Question 17

pedi dose

Answer 17

.15 mg

Question 18

list symptoms

Answer 18

swelling, flushing, warm, tingling feeling in face, mouth, chest, feet or hands

Question 19

for a pt epi is only given when they have trouble breathing or blood pressure bad

Answer 19

epi

Question 20

you respond to a child with hives and good blood pressure

Answer 20

take to hospital and monitor in route

Question 21

anaphylaxis

Answer 21

respiratory arrest or signs and symptoms of shock

Question 22

side effects of epi

Answer 22

Epinephrine is a chemical that narrows blood vessels and opens airways in the lungs. These effects can reverse severe low blood pressure, wheezing, severe skin itching, hives, and other symptoms of an allergic reaction.

• Increased heart rate
• Increased cardiac workload

Question 23

Allergic Reactions

Answer 23

• Immune system naturally responds to foreign substances in body

Question 24

Allergic reaction

Answer 24

exaggerated response to foreign substance

Question 25

Allergen

Answer 25

substance causing exaggerated effect

Question 26

Body’s Reaction to Allergen | • First exposure

Answer 26

– Immune system forms antibodies – Antibodies identify and attack particular foreign substance – Antibodies combine only with allergen they were formed in response to

Question 27

Body’s Reaction to Allergen | • Second (and subsequent) exposures

Answer 27

– Antibodies exist – Antibody combines with allergen, leading to release of histamine and other chemicals into bloodstream – Chemicals cause harmful effects

Question 28

• Effects of histamine and other chemicals

Answer 28

– Inflammation (swelling) – Bronchoconstriction – Vasodilation

Question 29

Anaphylaxis

Answer 29

• Severe, life-threatening allergic reaction • Can cause: – Dilation of blood vessels (hypotension) – Airway swelling (airway obstruction) – Bronchoconstriction (respiratory failure)

Question 30

Common Allergens

Answer 30

``` • Insects • Foods • Plants • Medications • Others – Dust, makeup, soap, etc. ```

Question 31

Latex Allergy

Answer 31

• Common concern in EMS – Many patients have latex sensitivity – Providers can develop latex allergy from prolonged exposure

Question 32

Course of Reaction

Answer 32

``` • No way to predict exact course of an allergic reaction • Severe reaction often takes place immediately, but can be delayed 30 minutes or more • Mild allergic reaction can rapidly progress to anaphylaxis ```

Question 33

Signs and | Symptoms: Skin - Allergic Reactions

Answer 33

* Swelling * Flushing (red skin) * Warm, tingling feeling in face, mouth, chest, feet, or hands * Hives

Question 34

Signs and | Symptoms: Respiratory - Allergic Reaction

Answer 34

* Tightness in throat or chest * Cough * Rapid, labored, and/or noisy breathing * Hoarseness, muffled voice, loss of voice * Stridor * Wheezing

Question 35

Signs and | Symptoms: Cardiac - Allergic Reaction

Answer 35

* Increased heart rate | * Decreased blood pressure

Question 36

Signs and | Symptoms: Generalized - Allergic Reaction

Answer 36

* Itchy, watery eyes and/or runny nose * Headache * Feeling of impending doom

Question 37

Signs and Symptoms: Anaphylactic Shock

Answer 37

``` • Altered mental status • Flushed, dry skin or pale, cool, clammy skin • Nausea or vomiting • Changes in vital signs – Increased pulse, respirations – Decreased blood pressure ```

Question 38

Distinguishing Anaphylaxis from Mild Allergic Reaction

Answer 38

* Any of previous signs and symptoms can be associated with an allergic reaction * Anaphylaxis: patient has either respiratory distress or signs and symptoms of shock

Question 39

Assessment Allergic Reaction

Answer 39

``` • Primary assessment • Identify and treat life-threatening problems – Airway – Breathing – Circulation ``` ``` • History and physical exam – History of allergies – Exposure • What was the patient exposed to? • How (what method/route) was the patient exposed? – Signs and symptoms – Progression – Interventions ```

Question 40

Treatment: Allergic Reaction

Answer 40

• Manage patient’s airway and breathing • Apply high-concentration oxygen • Provide artificial ventilations if patient is not breathing adequately • Consider assisting patient with epinephrine auto-injector • If patient is not wheezing or showing signs of respiratory distress or shock – Continue with assessment – Consult medical direction regarding use of auto-injector

Question 41

Use of Auto-Injector

Answer 41

• When use of auto-injector may be appropriate – If patient has come in contact with substance that caused allergic reaction in the past – If patient also has respiratory distress or exhibits signs and symptoms of shock

Question 42

After Administering Auto-Injector

Answer 42

* Record administration of auto-injector * Transport patient * Reassess

Question 43

Additional Doses of Epinephrine

Answer 43

• Reassessment may show patient condition deteriorating • Additional doses of epinephrine may be necessary • Requires on-line medical control • Requires bringing patient’s additional auto-injectors in ambulance

Question 44

Additional Doses of Epinephrine

Answer 44

• If no auto-injector available – Request ALS intercept – Treat for shock

Question 45

Think About It

Answer 45

* Should you administer an auto-injector for a simple allergic reaction? * What assessment findings would indicate the need for epinephrine?

Question 46

Epinephrine

Answer 46

* Commonly prescribed to patients with a history of allergy * Auto-injectors are common for people to carry or have at home * Hormone produced by body * Constricts blood vessels * Dilates bronchioles

Question 47

Side Effects of Epinephrine

Answer 47

* Increased heart rate | * Increased cardiac workload

Question 48

Auto-Injector

Answer 48

* Spring-loaded needle and syringe with a single dose of epinephrine * Upon administration, medication automatically releases and injects

Question 49

Administering Auto-Injector

Answer 49

``` • Injection site typically anterior-medial thigh (midway between waist and knee) • Remove clothing from site if possible • Use standard precautions • Remove cap • Press tip of auto-injector firmly against patient’s thigh • Once needle is deployed, allow full injection of medication before removing from injection site • Carefully discard auto-injector into sharps container ```

Question 50

Pediatric Note

Answer 50

• Two sizes of auto-injectors – Adult dose: 0.3 mg – Children’s dose (for child less than 66 pounds): 0.15 mg

Question 51

Chapter Review - Allergic

Answer 51

• Patients with anaphylaxis will be extremely anxious. Their bodies are in trouble and are letting them know it. • The signs and symptoms of anaphylaxis result from physiological changes: vasodilation, bronchoconstriction, leaky capillaries, and thick mucus • By quickly recognizing the condition, consulting medical direction, and administering the appropriate treatment, you can literally make the difference between life and death for these patients.

Question 52

Remember - Allergic

Answer 52

• In an allergic reaction, the body’s immune system overreacts to an allergen and causes potentially harmful side effects. • Anaphylaxis is a severe, systemic form of allergic reaction; it is a life-threatening emergency.

Question 53

Remember - Allergic

Answer 53

• EMTs must use assessment to differentiate a localized allergic reaction from a systemic anaphylactic reaction. • Epinephrine is useful in anaphylaxis because it constricts dilated blood vessels and opens bronchial passages. • Epinephrine has potentially dangerous side effects and should be used only in the event of anaphylaxis.

Question 54

Questions to Consider - Allergic

Answer 54

• What are the indications for administration of an epinephrine auto-injector? • List some of the more common causes of allergic reactions.

Question 55

Questions to Consider - Allergic

Answer 55

• List signs or symptoms of an anaphylactic reaction associated with each of the following: – Skin – Respiratory system – Cardiovascular system

Question 56

Critical Thinking - Allergic

Answer 56

• A 24-year-old male ate a meal that he believes contained shellfish. He is allergic to shrimp. He is sweating and nervous. He appears to be breathing adequately. You do not note any wheezing or stridor

Question 57

Critical Thinking - Allergic

Answer 57

• His face is slightly red. His pulse is 88 strong and regular, respirations 24, blood pressure 108/74, and skin warm and moist. Should you administer epinephrine?

Question 58

degranulation

Answer 58

Degranulation is a cellular process that releases antimicrobial cytotoxic molecules from secretory vesicles called granules found inside some cells. It is used by several different cells involved in the immune system, including granulocytes (neutrophils, basophils and eosinophils) and mast cells. It is also used by certain lymphocytes such as natural killer (NK) cells and cytotoxic T cells, whose main purpose is to destroy invading microorganisms.

Question 59

mast cells

Answer 59

A mast cell (also known as a mastocyte or a labrocyte) is a resident granulocyte of several types of tissues that contains many granules rich in histamine and heparin. Although best known for their role in allergy and anaphylaxis, mast cells play an important protective role as well, being intimately involved in wound healing and defense against pathogens.

Question 60

hypersensitivity

Answer 60

an exaggerated response by the immune system to a particular substance

Question 61

histamine

Answer 61

Histamine is an important protein involved in many allergic reactions. Allergies are caused by an immune response to a normally innocuous substance (i.e. pollen, dust) that comes in contact with lymphocytes specific for that substance, or antigen. In many cases, the lymphocyte triggered to respond is a mast cell. For this response to occur, a free-floating IgE (an immunoglobulin associated with allergic response) molecule specific to the antigen must first be attached to cell surface receptors on mast cells. Antigen binding to the mast cell-attached IgE then triggers the mast cell to respond. This response often includes the release of histamine (Janeway et al 1999).