Snakes Flashcards
What are the clinical syndromes that can occur with snakebite?
COAGULOPATHY
Venom induced consumptive coagulopathy (VICC)
- Tiger, Brown, Taipan
- Fibrinogen —> fibrin.
— elevated/unrecordable PT, aPTT, INR
— low/undetectable fibrinogen
— elevated Ddimer
- Onset within 1 hour
- BAD
- Leads to:
1- BLEEDING
2- Small vessel thrombi —> AKI —> microangiopathic haemolytic anaemia (MAHA) (after 3 days)
Anticoagulant Coagulopathy (AC)
- Black snakes (mulga, red bellied)
- Raised APTT
- Not usually significant
NEUROTOXICITY
- Descending paralysis- *ptosis, facial, bulbar, eyes, resp…
MYOTOXICITY
- Pain, tenderness, weakness
- Rhabdo, AKI
LOCAL
Which snakes cause VICC?
+- MAHA
Tiger
Brown
Taipan
Which snakes cause AC?
Black
- Mulga
- Red-bellied
APPROACH TO SNAKEBITE:
FIRST AID
Immobilise whole patient
Pressure bandage to site- gauze compression if not bandageable
- Bite site first
- Then, whole limb dist to prox
- within 4 hours
Splint limb
RISK ASSESSMENT
- Likelihood of envenomation
—> history
—> clinical
- Snake ID
—> geography/ description/ syndrome/ expert/ VDK
SEEK AND TREAT ENVENOMATION
Examination
- ?Ptosis, eye movements, facial strength
- ?tender muscles
- ?bleeding gums, bite site
Ix
Immediate bloods- coags, fibrinogen, Ddimer, FBC and film, UEC, CK, LDH
Swab for poss VDK
NO evenomation seen:
- Remove PIB in resus area
- Regular clinical exam
- Repeat bloods 1 hour post PIB off + 6, 12 hours post bite
YES envenomation:
- Resus area, anaphylaxis-ready
- Give antivenom
- Release PBI after
- Repeat bloods 6, 12 and 24 hours post bite
- If VICC and bleed, FFP.
DISCHARGE
ADT
Counsel re serum sickness, MAHA
Types of snake antivenom available:
MONOVALENT
Brown
Tiger
Black
Death Adder
Taipan
Sea
When snake identifiable by appearance/ geography/ clinical/ expert/ venom detection kit
POLYVALENT
Everything except Sea snake
Large volume and higher risk anaphylaxis
When snake unidentifiable
NOT IN TAS- only need Tiger
NOT IN VIC- only need Brown plus Tiger
Indications for snake antivenom:
Any evidence of envenoming!
Collapse
Neurotox: ptosis or worse
Myotox: muscle pain, CK >1000
Coagulopathy: AC, VICC
Nonspecific (eg. Headache, abdo pain, vomit…) = possibly. Discuss with toxicologist
What is the dose of snake antivenom in children?
As for all antivenom, same as adult
For snake, 1 vial, no repeats
Snake antivenom:
How to give
Complications
Resus bay and full monitoring
Adrenaline at hand
Dose is 1 vial, adults and children
Never repeated
Dilute 1 in 10 with saline, give over 15mins
(Neat push in slow arrest)
ALLERGIC REACTION IN UP TO 20%
Proper anaphylaxis/ shock in 5% (poly) and 1% (mono)
Highest risk polyvalent, Tiger
Serum Sickness
Days to weeks after
Give 5 days of pred
Management of antivenom anaphylaxis.
Stop!
Usual: IM adrenaline, Fluids
Once stable, can restart antivenom WITH adrenaline infusion going.
Snake venom detection kit (VDK):
Swab or urine- NEVER BLOOD
NOT for confirming envenomation. High false positive rate. For ID only when envenomation proven in other ways.
Not really useful in Tas or Vic, where not trying to avoid polyvalent.
Which main clinical syndromes do these snakes cause?
Tiger
Brown
Black
Taipan
Death Adder
TIGER
VICC (+- MAHA)
Sometimes: neuro, myo
BROWN
VICC (+- MAHA)
Collapse, arrest
Neuro
TAIPAN
VICC (+- MAHA)
Neuro
Myo
BLACK (incl mulga)
AC
Myo
DEATH ADDER
Isolated neurotox
NO LAB DERANGEMENTS, no anticoag
