Case 03 · Toxinology
Neurotoxic snake bite (common krait)
A 22-year-old farm labourer wakes before dawn with abdominal pain, and by sunrise he cannot keep his eyes open. Nobody saw a snake. Recognise krait envenoming, give antivenom early, handle the reaction it can cause, and ventilate before paralysis reaches his breathing.
About this case
What you will practise
Learning objectives
- Recognise neurotoxic envenoming when no bite was seen: night-time floor sleeping, abdominal pain, ptosis and descending paralysis.
- Give safe first aid and avoid harmful traditional measures.
- Use the 20-minute whole blood clotting test and start ASV at the right dose without a test dose.
- Recognise and treat an early anaphylactic reaction to ASV, then complete the infusion.
- Monitor breathing with single breath count and blood gases, not SpO₂ alone, and ventilate in time.
- Decide on a repeat ASV dose, run a neostigmine trial safely, and plan ICU care and prevention.
Key decisions this case tests
- How much ASV, how fast, and with or without premedication?
- What to do the moment the rash and wheeze appear.
- Is “SpO₂ 95% on oxygen” reassuring?
- When to bag, when to intubate.
- Neostigmine: with atropine first, and what a krait response looks like.
Reference basis
- Ministry of Health and Family Welfare, Government of India. Standard Treatment Guidelines: Management of Snake Bite (National Snakebite Management Protocol).
- WHO Regional Office for South-East Asia. Guidelines for the management of snakebites, 2nd edition, 2016.
- Bhalla A et al. Manual ventilation in respiratory paralysis due to Indian common krait bite. Asia Pac J Med Toxicol 2014;3:55–8.
Content version 1.0 · November 2026 · clinical review pending. See the Clinical content policy.
Before you start
The physiology is a simplified teaching model: paralysis, the ASV effect and the reaction are timed for learning, not prediction. Doses follow the cited protocols but have not yet been signed off by a clinician.
Visle is for education only and is not medical advice. A real snake bite needs urgent hospital care: keep the person still and get them to the nearest hospital with antivenom.
Ready for another emergency?
Case 02 puts you in front of a severe organophosphate poisoning that needs fast, careful atropine titration.