Allergy

Question 1

Mechanism of Allergy

Answer 1

Two ways:

1. IgE mediated: exposure → sensitization → re-exposure triggers reaction
2. Direct: first exposure causes the reaction, eg: contrast dye

Question 2

What are the common causative agents, triggers, of Allergy reaction

Answer 2

3 main causes/agents:
insect bites
Meds, latex
food: peanuts, tree nuts (walnuts, hazelnuts, almonds, cashews, pecans, pistachios), shell fish,

Question 3

Clinical Features of Allergy?

Answer 3

General: anxiety, tremor
Skin: urticaria, edema, erythema, pruritus
Resp: SOB, throat tightness, cough, wheeze, stridor, sneezing
Eyes: itching, tearing
CVS: hypotension, tachycardia, arrhythmia, MI
GI: abdo pain, N/V/D

Question 4

What kind of history question should you ask regarding an allergy/allergic reaction?

Answer 4

Med/exposure, indication, course # doses
Timing of reaction after exposure, how long did it last? what Tx was given
Ask about all symptoms (explained/unexplained)

Question 5

What are the possible complications of an allergic reaction?

Answer 5

cardiovascular collapse
airway obstruction
death

Question 6

General approach to a patient with allergies/allergic reaction?

Answer 6

inquire, document and revaluate allergies regularly
Clarify reaction
Give appropriate meds: antihistamines, bronchodilators, steroids, EpiPen
Educate on anaphylaxis and EpiPen use (patient must f/u after EpiPen use), emergency action plan
Medic alert bracelet
specialist follow-up

Question 7

Define Anaphylaxis

Answer 7

Anaphylaxis is an acute, potentially life-threatening hypersensitivity reaction, involving the release of mediators from mast cells, basophils and recruited inflammatory cells. Anaphylaxis is defined by a number of signs and symptoms, alone or in combination, which occur within minutes, or up to a few hours, after exposure to a provoking agent. It can be mild, moderate to severe, or severe. Most cases are mild but any anaphylaxis has the potential to become life-threatening.

Anaphylaxis develops rapidly, usually reaching peak severity within 5 to 30 minutes, and may, rarely, last for several days.

Question 8

Clinical Criteria for Dx of Anaphylaxis?

Answer 8

Question 9

How does Epinephrine Work?

Answer 9

inotrope and a vasopressor
with alpha 1, 2 and beta 1, 2

Question 10

Management of Anaphylaxis - Epi dose?

Answer 10

ABC
don’t delay EPI
Moderate Anaphylaxis
Adults 0.01 mg/kg to a max of 0.3-0.5mg of a 1:1000 solution given intramuscularly, preferably in the anterolateral thigh, every 5-15 minutes or as necessary.
Children 0.01 mg/kg to a maximum of 0.3mg intramuscularly, preferably in the anterolateral thigh, every 5-30 minutes as necessary
Severe Anaphylaxis
Adults: 1ml 1:10,000 IV or ETT
Children: 0.01ml 1:1000 IV or ETT

Infusion:
Exact: 5-10 mcg IV per minute
in practice: 1mg of Epi into 1L of NS (1mcg per mL) put on an infusion pump running at 5-10 mL per minute (300-600 mL per hour)

Question 11

Management of Anaphylaxis - Other Meds?

Answer 11

Benadryl 50m IM or IV q 4-6h
Methylprednisolone 50-100mg IV depending on severity
Ventolin - if bronchospasm present
Glucagon - if on beta-blocker and hypotensive

Do NOT use antihistamine as first-line agent. It does NOT prevent CV/Resp symptoms and can delay the action of Epi.