Snakebite and envenomation for Indian ICUs: recognising neurotoxic and haemotoxic syndromes, the 20-minute whole blood clotting test, ASV dosing and reactions under the national protocol, ventilation and the neostigmine trial for neuroparalysis, scorpion sting with prazosin, and bee and wasp stings.
6 topics
- 01
Recognising envenoming: Big Four and syndromes
Treat the syndrome, not the snake. Classify early as neurotoxic (ptosis, bulbar weakness, respiratory failure) or haemotoxic (incoagulable blood, bleeding, swelling, AKI), apply sensible first aid, avoid harmful traditional measures, and observe every bite for at least 24 h.
6 stepsAlgorithmNew - 02
20WBCT and venom-induced coagulopathy
The 20-minute whole blood clotting test is the bedside decider for haemotoxic envenoming in India. Use a new clean dry glass tube, do it serially, and do not let a single normal result reassure you; ASV, not FFP, corrects VICC.
5 stepsAlgorithmNew - 03
ASV dosing and adverse reactions
Give 10 vials of polyvalent ASV IV over an hour for systemic envenoming, the same dose for children and pregnant women, with no test dose and adrenaline drawn up. Repeat by the 6-hour rule (haemotoxic) or 1-2-hour rule (neurotoxic), and manage reactions by pausing, adrenaline IM and restarting.
6 stepsAlgorithm2 dosesNew - 04
Neuroparalysis: airway, ventilation and neostigmine
Neurotoxic envenoming kills by respiratory failure, which is completely survivable with timely intubation and ventilation. Monitor bulbar function and breath count, intubate early, give ASV, and try atropine-neostigmine, which helps cobra bites far more than krait.
5 stepsAlgorithm1 dosesNew - 05
Scorpion sting (Indian red scorpion) and prazosin
Mesobuthus tamulus stings cause an autonomic storm with hypertension, myocardial dysfunction and pulmonary oedema, especially in children. Prazosin is the cornerstone; scorpion antivenom added to prazosin speeds recovery.
5 stepsAlgorithm1 dosesNew - 06
Bee, wasp and hornet stings
Most sting deaths are from anaphylaxis, treated with IM adrenaline. Massive envenomation from multiple stings causes delayed toxicity – rhabdomyolysis, haemolysis, AKI, myocardial injury – even without allergy; monitor for 24 h.
5 stepsAlgorithmNew
Drugs in this module
Doses written for this module's context. The same drug may read differently in another module.
Anti-snake venom (polyvalent ASV)
Equine F(ab')2 polyvalent antivenom (Big Four)
Anti-snake venom (polyvalent ASV)
Equine F(ab')2 polyvalent antivenom (Big Four)
- Indications
- Systemic envenoming (incoagulable 20WBCT, spontaneous bleeding, neuroparalysis, shock, AKI, rhabdomyolysis) or rapidly progressive local swelling (> half the limb, or within hours).
- Adult dose
- 10 vials IV (reconstituted, in ~200 mL NS) over 1 h; same dose for children and pregnant women. Haemotoxic: repeat 10 vials if 20WBCT still incoagulable at 6 h (usual max 25-30 vials). Neurotoxic: repeat 10 vials if no improvement at 1-2 h (usual max 20 vials).
- Preparation (India)
- Lyophilised vials (each neutralises a stated mg of each venom per 10 mL); reconstitute with 10 mL water for injection. Several Indian manufacturers (e.g. Bharat Serums, VINS, Premium Serums).
- Cautions
- No test dose (poor predictive value, delays treatment). Early anaphylactoid reactions in up to ~20-40%: keep adrenaline drawn up. Pyrogenic reactions; serum sickness at 5-24 days.
Adrenaline (epinephrine)
Sympathomimetic
Adrenaline (epinephrine)
Sympathomimetic
- Indications
- ASV reactions, anaphylaxis to Hymenoptera stings; shock.
- Adult dose
- 0.5 mg IM (0.5 mL of 1 mg/mL) into anterolateral thigh, repeat every 5-15 min; child 0.01 mg/kg IM (max 0.5 mg). Refractory: IV infusion 0.05-0.5 mcg/kg/min.
- Preparation (India)
- 1 mg/mL (1:1000) 1 mL ampoules.
- Cautions
- Never give 1 mg/mL IV as a bolus. Tachyarrhythmia, hypertension.
Neostigmine
Anticholinesterase
Neostigmine
Anticholinesterase
- Indications
- Neostigmine trial in neurotoxic (especially cobra, postsynaptic) envenoming with ptosis or weakness.
- Adult dose
- After atropine 0.6 mg IV: neostigmine 1.5 mg IV (or 0.5 mg IM); if improvement, continue 0.5 mg IV every 30 min (up to 5 doses), then taper. Child: atropine 0.05 mg/kg + neostigmine 0.04 mg/kg.
- Preparation (India)
- 0.5 mg/mL 1 mL ampoules (Myostigmin).
- Cautions
- Always pre-treat with atropine (bradycardia, bronchorrhoea). Little benefit in krait (presynaptic) bites.
Atropine
Antimuscarinic
Atropine
Antimuscarinic
- Indications
- Premedication before neostigmine; bradycardia and cholinergic features in scorpion sting only if severe (generally avoided).
- Adult dose
- 0.6 mg IV before each neostigmine dose (child 0.05 mg/kg).
- Preparation (India)
- 0.6 mg/mL 1 mL ampoules.
- Cautions
- Avoid routine use in scorpion sting – worsens the adrenergic storm.
Prazosin
Alpha-1 adrenergic blocker
Prazosin
Alpha-1 adrenergic blocker
- Indications
- Indian red scorpion (Mesobuthus tamulus) sting with autonomic storm: hypertension, tachycardia, cold extremities, pulmonary oedema risk.
- Adult dose
- 30 mcg/kg orally (adult typically 0.5-1 mg) every 3 h until peripheries warm and features resolve; via nasogastric tube if needed.
- Preparation (India)
- 1 mg, 2 mg, 5 mg tablets (Minipress XL is extended-release – use immediate-release where possible).
- Cautions
- First-dose postural hypotension – keep supine; correct volume. Extended-release preparations act too slowly.
Module references (5)
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