Snake venom poisoning
Snake bites are an important cause of death in rural agricultural communities world wide, if you’re outside of the UK, this matters. First, know your snakes, some selected countries below:
- UK - Vipers only - specifically the common european viper known as the adder
- Bulgaria - Vipers only - horned viper and common european viper
- Europe - only vipers apparently
- Australia - Elapids only
- Americas - Elapids and Pit-Vipers
- Asia - loads! Elapids, vipers, pit-vipers, back-fanged colubrids
Image: “Benny Trapp Vipera ammodytes” by Benny Trapp, CC BY 3.0, via Wikimedia Commons.
Clinical features
- Common european viper (adders)
- Local pain and paraesthesia, swelling, bruising, inflammation, lymphangitic lines, lymphadenopathy (local)
- Hypotension (can be early, late, recurrent or sustained (with or without shock)
- Anaphylactic features (urticaria, angio-oedema, bronchospasm)
- Myocardial abnormalities
- GI bleeding
Useful labs
- FBC - expect neutrophil leukocytosis and haemoconcentration later
- Blood film - look for schistocytes
- Blood coagulation - decrease in coagulation, increased PT, increased INR
- Biochem
Management
- First aid
- remove tight clothing, rings etc from limb
- Do not put ligature, ice pack etc on wound
- Pressure immobilization (with bandage, covering whole limb) and pressure pad can help delay systemic absorption by compressing lymphatics - not necessary in bites from common european viper
- Hospital treatment
- Give specific antivenom (hyper-immune animal serum immunoglobulins), administered with IV infusion/injection
- Treat hypovolemic shock supportively
- Respiratory failure will require endotracheal intubation
- AKI may necessitate dialysis
- Wound infection/necrotic tissue, treat with surgery