case study

patient X
30 year old male

triage notes

• 1520hrs: scratch to left lower leg. noticed at work 20 minutes ago. feeling nauseated. pain at scratch. nvasc intact.
• fast-track: category 5

thoughts?

initial nursing notes

• 1530hrs: 30 year old male presents with scratch to left lower shin. c/o localised pain. unsure of mechanism - noticed approximately 20 minutes ago whilst at work as landscaper. A-patent, B-normal WOB, nil SOB, C-pink and warm, weak radial pulse, BP 95/60. D-pain/redness at site. nil analgesia taken.

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what is your differential diagnosis?

aditional nursing notes

• 1545hrs: uptriage cat 2. pt became dizzy. brief ACS. feels nauseated. c/o headache/stomach pain.1 x vomit. 18G IVC inserted R forearm. bloods taken and sent.

snake bite is suspected

what next?

venom detection kit
(VDK)

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• uses bite site swabs to determine which antivenom is needed
• not used to confirm or exclude envenoming
• false positives and negatives are common
• should be interpreted in context
• request swabs from pathology

well 1 turns deep blue followed by well 7 then well 2

based on geography and clinical and laboratory data its likely to be a brown snake or tiger snake

patient management

• keep the patient calm
• DO NOT wash the wound
• treat symptoms
• first aid - even in late presentations
• vital signs can vary - initial hypotension followed by hypertension

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• the most common route for envenoming is via the lymphatic system
• lymph is transported by muscle movement
• DO NOT remove PIB if insitu
• if not insitu put one insitu!
• resuscitation takes precedence

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• no evidence of a superior technique
• distal - proximal: improves comfort but risk of increased venom movement
• proximal - distal: minimises venom movement but may cause distal odema and discomfort
• elasticised bandage preferred but use what you have

aditional nursing notes

• 1630hrs: L facial deformity. pt c/o generalised aches and muscle weakness. dr informed.

neurotoxicity

pressure immobilisation bandage

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• due to presynaptic and postsynaptic neurotoxins in venom
• causes a progressive descending flaccid paralysis

ptosis - facial bulbar involvement - paralysis of respiratory muscles - peripheral weakness

myotoxicity

some snakes' venom contain myotoxins that cause rhabdomyolysis, muscular aches, pains, weakness, raised CK and myoglobinuria.
severe rhabdomyolisis can result in renal failure

blood test results:

what does this mean?

venom induced consumptive coagulopathy (VICC)

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• immeasurably high INR and aPPT
• unmeasurable fibrinogen
• positive D-dimer

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• procoagulant toxins activate the clotting pathway resulting in consumption of clotting factors
• causes a broad range of factor deficiencies
• clot and bleed

to give or not to give

monovalent

• tiger snake - tiger/copperhead/sea/ RBB/rough scaled/stephen's banded
• brown snake - brown/dugite/gwarder
• black snake - king brown/mulga/RBB
• death adder - death adders
• taipan - taipans

polyvalent

• neutralises venom from all important venomous snakes
• large volumes cary increased risk of adverse reactions

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• mainstay of treatment with systemic envenoming
• neutralises toxins and allows time for recovery
• use in caution with horse allergy
• how much?...
• which one?...

how much?

• practice has recently changed
• commonly used to give multiple doses
• has not been found to be adventageous

over 100 venomous snakes in Australia

the most deadly belong to the front-fanged elapid family

what snake is this presentation consistent with?

deadly Victorian snakes

eastern brown snake

pseudonaja textilis

• one of the deadliest snakes in the world
• 1/14 000 of a tablespoon of venom is enough to kill a person
• causes severe coagulation disturbance including VICC, neurotoxicity, occasional nephrotoxicity
• death can be quick and sudden

tiger snake

notechis scutatus

• bites more Victorians than any other snake
• untreated mortality is approximately 45%
• causes severe coagulation disturbances including VICC and slow onset neurotoxicity, rhabdomyolisis

copperhead snake

austrelaps supurbus

• injects a large amount of venom
• rarely fatal
• rarely causes coagulopathy, neurotoxicity and myotoxicity

red bellied black snake

psuedechis porphyriacus

• venom not as potent as other snakes
• can jump in the air
• no recorded deaths
• venom has coagulopathic, neurotoxic and myotoxic actions

yellow bellied sea snake

pelamis platurus

• the most widely ranging snake in the world
• unusual to have contact with humans unless washed ashore
• causes neurotoxicity and myotoxicity
• no recorded deaths in Australia

who dunnit?

tiger snake!

be wary...

serum sickness

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• 5-10 days after antivenom
• fever, rash, headache, arthralgia, myalgia
• treated with corticosteroids (prophylactically if >25ml antivenom)

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• stick bites
• geographical anomalies
• asymptomatic patient with positive blood results

what else?

fun facts!

• approximately 3000 suspected snake bites around Australia each year - 10% require antivenom
• you are more likely to die from anaphylaxis to bee sting than a bite from a snake
• brown snakes responsible for the most bites Australia wide
• median time to recovery of INR

snakebite in geelong

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references

• Geoffrey K Isbister, Simon G A Brown, Colin B Page, David L McCoubrie, Shaun L Greene and Nicholas A Buckley 2013, 'Snakebite in Australia: a practical approach to diagnosis and treatment', Med J, vol. 199, no. 11, pp. 763-768.
• Nickson, C 2009, 'Snakebite vs stickbite', Life In The Fast Lane, http://lifeinthefastlane.com/toxicology-conundrum-005/
• Nickson, C 2010, 'Snakebite envenoming challenge', Life In The Fast Lane, http://lifeinthefastlane.com/toxicology-conundrum-026/
• Nickson, C 2012, 'Another bloody snakebite', Life In The Fast Lane, http://lifeinthefastlane.com/toxicology-conundrum-051/
• Sutherland, S 2014, 'Australian snakebites', http://sydney.edu.au/medicine/anaesthesia/resources/venom/snakebite.html
• CSL 2007, 'Snake venom detection kit', CSL ltd, http://www.csl.com.au/docs/92/398/SVDK_Product_Leaflet,0.pdf
• Maduwage, K, Isbister, G 2014, 'Current treatment for venom-induced consumption coagulopathy resulting from snakebite', PLOS, http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0003220