What type of reaction causes Anaphylaxis?
Type 1 Hypersensitivity reaction
What is the pathophysiology of Anaphylaxis?
IgE stimulates Mast cells to release Histamine (aka Mast cell degranulation)
How is the Dx of Anaphylaxis made?
Clinical
What is the key CF that differentiates Anaphylaxis from non-anaphylactic allergic reaction?
Airway / breathing / circulation compromise
(ABC)
What can the CF of Anaphylaxis be divided into?
ABCDE
(emergency examination tings)
What are the AIRWAY CF of Anaphylaxis? (5 things)
- Lip / tongue / pharynx / epiglottis swelling
- Cough
- Swallowing difficulty
- Hoarse voice
- Stridor
What are the BREATHING CF of Anaphylaxis? (7 things)
- Tachypnoea / SOB
- Cough
- Wheezing
- Laryngeal oedema
- Bronchospasm
- Chest tightness
- Hypoxia / Hypercapnia
What are the CIRCULATION CF of Anaphylaxis? (6 things)
- Dizziness / Drowsiness / Collapse
- Pallor
- Tachycardia / Arrhythmias / ECG changes
- Hypotension
- Clammy skin
- Prolonged CRT
Why do you get Circulation CF in Anaphylaxis? (3 steps)
- Peripheral vasodilation + Increased permeability
- Plasma leakage from circulation
- Decreased intravascular volume
What are the DISABILITY / OTHER CF of Anaphylaxis? (6 things)
- Neuro: Confusion / Anxiety / Collapse
- GI: Abd cramping / DnV
- Other: Feeling of impending death
What are the EXPOSURE CF of Anaphylaxis? (4 things)
- Angioedema (puffy lips / eyes)
- Urticaria (see pic)
- Pruritis (itchy skin)
- Erythema
What can the Differential Dx similar to Anaphylaxis be divided into? (2 things)
- Life threatening DDx
- Non-life threatening DDx
What are the Life threatening DDx that present similarly to Anaphylaxis? (3 things)
- Life-threatening Asthma
- Septic shock
- Hereditary Angioedema
What makes Life threatening Asthma different from Anaphylaxis? (2 things)
- Resp features
- No Skin / CVS / GI features
What makes Septic shock different from Anaphylaxis?
Temp below 36 / above 38
(temp usually normal in anaphylaxis)
What makes Hereditary Angioedema different from Anaphylaxis?
No urticaria
What are the NON-Life threatening DDx that present similarly to Anaphylaxis? (4 things)
- Vasovagal episode
- Panic attack
- Breath-holding episode
- Idiopathic (non-allergic) urticaria / angioedema
What is a Breath-holding episode?
When a kid invol holds their breath after being angry / frustrated / startled / in pain
What makes a Vasovagal episode different from Anaphylaxis? (4 things)
- No urticaria / angioedema / hoarseness / wheezing
- Bradycardia (instead of tachy in anaphylaxis)
- Pallor (instead of erythema in anaphylaxis)
- Improves on lying down
What makes a Panic attack different from Anaphylaxis? (3 things)
No urticaria / hypotension / wheeze
What makes a Breath-holding episode different from Anaphylaxis?
Usually resolves within 1 min
What makes Idiopathic (non-allergic) urticaria / angioedema different from Anaphylaxis?
Skin changes only, no other CF
What are the immediate Mx options for sus Anaphylaxis? (5 things)
- A: Secure Airway
- B: 100% High flow O2 // Salbutamol if wheezing
- C: IV fluids
- D: Lie pt flat (to improve cerebral perfusion)
- E: Look for flushing / urticaria / angioedema
How do you confirm Dx of Anaphylaxis?
Serum Mast Cell Tryptase within 6 hours of event
(impressive knowledge)
