🐍 Chapter 130: Snake Envenomation

Neurotoxic (elapids: cobra, krait) → descending paralysis · Haemotoxic (vipers) → coagulopathy, bleeding · 20WBCT · Antisnake venom (ASV) · Dose same as adults · Anaphylaxis risk · No tourniquet · No wound incision · Neostigmine trial for neurotoxic

🔍 Core Concepts: Snake Envenomation

📌 Types of Venom
Neurotoxic (elapids: cobra, krait) → descending paralysis, ptosis, respiratory failure. Haemotoxic (vipers) → coagulopathy, bleeding, swelling, renal failure. Cytotoxic → local necrosis.
🩸 20WBCT (20-Minute Whole Blood Clotting Test)
Bedside test for coagulopathy. Fresh blood in clean glass tube; check at 20 min. If unclotted → viper envenomation. Guides ASV dosing.
💊 Antisnake Venom (ASV)
Polyvalent ASV (effective against common local species). Indications: systemic envenoming (coagulopathy, neurotoxicity, haemorrhage) or severe local swelling. Dose: 8-10 vials initially (same for children as adults). Repeat based on clinical response/20WBCT.
⚠️ ASV Anaphylaxis
Stop infusion, give adrenaline (0.01 mg/kg IM), antihistamines, steroids. ASV is life-saving; restart after reaction with slower rate + premedication.
🫁 Respiratory Support
Neurotoxic envenomation → early intubation for descending paralysis, bulbar weakness. Neostigmine trial (anticholinesterase) may improve neurotoxicity in cobra bites.
🚫 First Aid DON'Ts
No tourniquet, no wound incision/suction, no ice, no electric shock, no herbal remedies. Immobilise limb, transport immediately.

🩺 Stepwise Approach: Snake Envenomation

1
First aid & immobilisation
Do NOT apply tourniquet, cut wound, suck venom, or ice. Immobilise limb (splint). Transport to hospital immediately. Remove jewellery/constrictive clothing.
2
Assess for envenomation (clinical)
Local: swelling, pain, bleeding. Systemic: neurotoxic (ptosis, ophthalmoplegia, descending paralysis, respiratory distress), haemotoxic (bleeding, coagulopathy), renal failure.
3
Perform 20WBCT (if viper suspected)
Place fresh venous blood in clean glass tube. Check at 20 min. If unclotted → coagulopathy → ASV indicated. Repeat 6h after ASV to assess response.
4
Administer antisnake venom (ASV)
Indications: systemic envenoming (coagulopathy, neurotoxicity, bleeding, shock) or rapidly progressing local swelling. Dose: 8-10 vials diluted in NS over 1h (same for children). No test dose. Monitor for anaphylaxis.
5
Manage ASV reactions
If anaphylaxis: stop infusion, give adrenaline 0.01 mg/kg IM, antihistamines, hydrocortisone. Restart ASV slowly after reaction subsides (premedicate).
6
Supportive care & monitoring
Neurotoxic: intubate early for respiratory failure. Neostigmine trial (0.04 mg/kg IV with atropine) may reverse neurotoxicity. Haemotoxic: monitor 20WBCT, platelets, fibrinogen. Renal failure: dialysis if needed. Tetanus prophylaxis.