[70] Anaphylaxis Flashcards

1
Q

What is anaphylaxis?

A

A severe, life-threatening, generalised or systemic hypersensitivity reaction

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2
Q

Is anaphylaxis common?

A

No, it’s actually rare

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3
Q

Why is anaphylaxis often fatal?

A

Rapid onset of symptoms and laryngeal oedema

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4
Q

In what age group do most cases of anaphylaxis occur?

A

Under 5’s

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5
Q

Why do most cases of anaphylaxis occur in under 5’s?

A

This is when food allergy is most prevalent

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6
Q

When do most cases of fatal anaphylaxis occur?

A

In adolescents

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7
Q

What is the most common cause of fatal anaphylaxis?

A

Nut allergy

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8
Q

What is responsible for the allergic reaction in anaphylaxis?

A

Release of inflammatory mediators and cytokines from mast cells and basophils

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9
Q

What are the two mechanisms that can underly anaphylaxis?

A
  • Immunological mechanism

- Non-immunological mechanism

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10
Q

What is the initial step in the immunological mechanism of anaphylaxis?

A

IgE binds to antigens forming a complex that activates receptors on mast cells and basophils

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11
Q

What happens as a result of activation of mast cell and basophil receptors?

A

There is a release of inflammatory mediators

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12
Q

Give an example of an inflammatory mediator involved in anaphylaxis

A

Histamine

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13
Q

What are the effects of the inflammatory mediators released by mast cells and basophils?

A
  • Increased contraction of bronchial smooth muscle
  • Vasodilation
  • Blood vessel leakage
  • Heart muscle depression
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14
Q

What does the non-immunological mechanism involve?

A

Substances directly causing degranulation of mast cells and basophils

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15
Q

What percentage of anaphylaxis in children is caused by food allergy?

A

85%

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16
Q

What are some other causes of anaphylaxis?

A
  • Insect stings
  • Drugs
  • Latex
  • Exercise
  • Inhalant allergens
17
Q

Is a cause of anaphylaxis always identified?

A

No

18
Q

What are the risk factors for developing anaphylaxis?

A
  • Asthma
  • Other atopic diseases
  • Higher socioeconomic status
19
Q

What can be used to assess the symptoms of anaphylaxis?

A

ABCDE assessment

20
Q

What is seen on Airway assessment in anaphylaxis?

A
  • Swelling
  • Hoarseness
  • Stridor
21
Q

What is seen on Breathing assessment in anaphylaxis?

A
  • Tachypnoea
  • Wheeze
  • Cyanosis
  • SpO2 <92%
22
Q

What is seen on Cardiovascular assessment in anaphylaxis?

A
  • Pale
  • Clammy
  • Hypotension
  • Drowsiness
  • Coma
23
Q

What is seen on assessment of Everything Else in anaphylaxis?

A

Urticaria/angioedema (not always)

24
Q

Should anaphylaxis be acutely investigated?

A

No - its a clinical diagnosis

25
Q

What investigations may be needed in the long-term management of anaphylaxis?

A

Allergy testing

26
Q

What are the differentials for anaphylaxis?

A
  • Allergic reaction
  • Angioedema
  • Asthma exacerbation
27
Q

How should anaphylaxis be immediately managed?

A
  • Adrenaline 1:1000 IM

- Changes in posture

28
Q

In what situations may posture changes help?

A
  • Difficulty breathing
  • Hypotension
  • Unconscious
29
Q

What position may help with difficulty breathing?

A

Sat up

30
Q

What position may help with hypotension?

A

Supine with legs in the air

31
Q

What position may help with unconsciousness?

A

Recovery position

32
Q

How should anaphylaxis be further managed?

A
  • Establish airway
  • High flow oxygen
  • IV fluids (20ml/kg crystalloids)
  • Chlorpheniramine (IM or slow IV
  • Hydrocortisone (IM or slow IV)
  • Salbutamol if wheeze
33
Q

How should a patient that has experienced anaphylaxis be monitored?

A
  • Pulse oximetry
  • ECG
  • BP
34
Q

What should be considered when forming a long-term management plan for anaphylaxis?

A
  • Acute management strategies

- Trigger avoidance training

35
Q

How should a long-term management plan be given?

A

As a written plan with instructions and adrenaline auto-injectors

36
Q

What may be effective in preventing future anaphylaxis in some cases?

A

Allergen immunotherapy

37
Q

What are the potential complications of anaphylaxis?

A
  • Death
38
Q

What can cause death in anaphylaxis?

A

Respiratory or circulatory failure