Bites & Stings

Question 1

Name the broad categories of snake venoms and the snake types

Answer 1

Patterns of envenoming
• Vipers: Local swelling, sometimes necrosis Coagulation abnormalities, bleeding and shock

• Elapids: Local effects minimal (except some cobras) Neurotoxicity predominates
• Seasnakes: No local effects. Severe myotoxicity and paresis

Question 2

What quick test can identify a likely significant poisoning long before a specific ID

Answer 2

Coagulopathy and bleeding
• Bleeding often combination of haemorrhagin activity and coagulopathy
• Life threatening bleeding may occur
• 20 minute whole blood clotting test extremely useful
for diagnosis of a coagulopathy
• 20 min WBCT requires limited resources – sensitivity 82% (72-90)
– specificity 98% (97-99)

Question 3

What are the major venom components?

Answer 3

Major venom components
• Cytotoxins: 
       Proteases, phospholipases
• Haemorrhagins:
       Components acting on clotting cascade and on 
        platelets
• Neurotoxins:
       Pre or post synaptic: paralysis
• Myotoxins:
       May lead to rhabdomyolysis

Question 4

Name the signs of neurological poisoning and their natural progression

Answer 4

Neurotoxic signs
• Close and regular observation necessary
• Initial ptosis, then ophthalmoplegia
• Bulbar weakness: Cardinal sign of pooling of secretions
• Progressive weakness
• Eventual respiratory failure due to paralysis of intercostal muscles and diaphragm

Question 5

Key diagnostic factors

Answer 5

Diagnosis
• Suspect upon history or clinical signs
• Dead snake vital for diagnosis of biting species
• Careful examination of wound site and lymph nodes
• Look for early signs of bleeding or neurotoxicity
• Early screen for coagulopathy – 20 min whole blood clotting test

Question 6

Management of snakebite and its complications

Answer 6

Management
• Antivenom in systemic or severe local envenoming
– Neurotoxicity
– Hypotension/shock
– Bleeding/coagulopathy
– Renal failure
– Extensive blistering/bruising/swelling

Question 7

Antivenom production and considerations for use

Answer 7

Antivenom:
Made by serially injecting horses with venom to produce IgG or fragments of antibody to the venom.

• Considerable variation in quality
• Considerable variation in neutralising capacity
• Has to be appropriate to local snake species
• Monospecific or polyspecific antivenoms: polyspecific active against a number of different species of snake (usually mixture of monospecific)

DOSE FOR CHILDREN IS EXACTLY THE SAME AS THE ADULT

Question 8

How do you monitor antivenom efficacy?

Answer 8

Monitoring antivenom
• Effective antivenom therapy should restore normal coagulation
• Check WBCT20 6-8 hrs after treatment
• Need repeated checks: recurrence of coagulopathy
may occur
• Response of neurotoxicity to antivenom varies: – Good response in post-synaptic neurotoxicity
– Poor response in pre-synaptically acting toxins

Question 9

How do you manage a bite acutely?

Answer 9

IMMOBILISE and do a full limb bandage at sprain bandage pressure. then SPLINT. preventing movement prevents dissemination of toxin.