Anaphylaxis

Question 1

What are the care objectives of Anaphylaxis

Answer 1

• IM adrenaline with minimal delay
• Airway and perfusion support
• Hospital-based observation (usually 4 hours) at a minimum

Question 2

What is anaphylaxis?

Answer 2

A severe, potentially life-threatening systemic hypersensitivity reaction

Question 3

What is the pathophysiology and presentation of anaphylaxis?

Answer 3

• Anaphylaxis can exist with any combination of the signs and symptoms, but may also be limited to a single body system (e.g. isolated hypotension or isolated respiratory distress in the setting of exposure to antigen that has caused anaphylaxis in the patient previously)
• Rapid onset (usually within 30 mins but may be up to 4 hours)
• Anaphylaxis can be difficult to identify. Cutaneous features are common though not mandatory. Irrespective of known allergen exposure, if 2 systemic manifestations are observed then anaphylaxis should be accepted

Respiratory

• respiratory distress, shortness of breath, wheeze, cough, stridor
• due to inflammatory bronchoconstriction or upper airway oedema

Abdominal

• pain/cramping
• nausea/vomiting/diarrhoea
• particularly insect bites and systemically administered allergens (medications)

Skin

• Hives, welts, itching, flushed, angioedema (lips, tongue)
• Due to vasodilation and vascular hyperpermeability

Cardiovascular
- hypotension
due to vasodilation and vascular hyperpermeability

Question 4

What are common allergens of anaphylaxis?

Answer 4

• insect stings
• food
• medications
• exercise induced (rare)
• Idiopathic - no external trigger (rare)

Question 5

What do you need to consider in patients with both anaphylaxis and asthma?

Answer 5

Asthma, food allergy and high risk of anaphylaxis frequently occur together, often in adolescence. Bronchospasm is a common presenting symptom in this group, raising the likelihood of mistaking anaphylaxis for asthma. A history of asthma increased the risk of fatal anaphylaxis.

Maintain a high index of suspicion for anaphylaxis in patients with a history of asthma or food allergy.

Question 6

When may an adrenaline infusion be commenced?

Answer 6

My MICA when two doses of IM adrenaline are unsuccessful. However IM Adrenaline every 5/60 is appropriate if MICA is not available or while the infusion is being prepared.

Question 7

What does R.A.S.H stand for? Referring to anaphylaxis.

Answer 7

R - Respiratory distress
A - Abdominal Symptoms
S - Skin/mucosal symptoms
H - Hypotension

Question 8

How many of the R.A.S.H symptoms are required to confirm exposure to antigen?

Answer 8

Two

Question 9

Should you sit or walk a patient with anaphylaxis?

Answer 9

No

Question 10

When should you request MICA for an anaphylaxis?

Answer 10

• Expected clinical course (e.g. history of ICU admission/multiple adrenaline doses)
• Hypotensive <90
• Medication as precipitating cause
• Respiratory symptoms/distress
• History of asthma or multiple co-morbidities/medications
• No response to initial IM adrenaline

Question 11

Recite the anaphylaxis CPG.