Scorpion sting and arthropod envenomation

Manage now— do this, in order

• Resuscitation precedes everything, including antivenom — treat the syndrome in front of you, not the animal you were told about. Keep the patient still, immobilise the stung limb with a splint, apply a pressure pad and dressing with a cold pack. No tourniquets, incision, cut-and-suck, suction devices, chemicals, electric shocks or cautery — and release an applied constricting device only with monitoring, IV access and resuscitation drugs ready, since release can deliver a venom bolus and collapse.
• Treat the pain — it drives the catecholamine surge that causes the cardiac complications. Lidocaine (lignocaine) 1% WITHOUT adrenaline infiltrated into the site or as a digital ring block, maximum 3 mg/kg (adult and child) — never an adrenaline-containing preparation in a digit, ear, nose or penis. Paracetamol 1 g orally/IV 6-hourly, maximum 4 g/24 h (child 15 mg/kg 6-hourly).
• Morphine 0.1 mg/kg IV titrated in 2 mg increments (child 0.1 mg/kg IV titrated) only with continuous pulse oximetry and immediate airway capability — opiates in a neurotoxic patient precipitate respiratory failure. Avoid NSAIDs where rhabdomyolysis, haemolysis, kidney injury or coagulopathy is suspected.Doctor / Nurse
• Continuous IV midazolam is the specific measure for agitation and involuntary movements and lowers catecholamine drive: cautious loading dose 0.05 mg/kg IV slowly, then titrated infusion — only with continuous monitoring and the capacity to ventilate.Doctor / NurseNot available at your setup — Infusion pump.
• Afterload reduction, not diuresis, is the cardiovascular target: prazosin 30 micrograms/kg orally, repeated 3-hourly until the peripheries are warm and dry (many adult regimens start with 0.5 mg; same weight-based dose in children). Give it supine and volume-replete, recheck BP at 15, 30 and 60 minutes — plan for first-dose hypotension. Alternatives: nifedipine, hydralazine or sodium nitroprusside with close BP monitoring — never crushed sublingual nifedipine.Doctor / Nurse
• Treat pulmonary oedema as cardiogenic, and do not pour in fluid: oxygen, upright positioning, non-invasive or invasive positive pressure as required, afterload reduction, and fluid restraint once crackles appear. Diuretics have a limited role — these patients are not fluid-overloaded; low cardiac output despite afterload reduction needs inotropic support (dobutamine), guided where possible by echocardiography.Doctor / Nurse
• Antivenom — only the correct species-specific product rapidly reverses cranial-nerve dysfunction and muscle hyperexcitability: give IV (slow undiluted push or infusion diluted in 0.9% sodium chloride) with adrenaline drawn up at the bedside, observing continuously and for at least one hour afterwards. Anti-snake venom does NOT neutralise scorpion venom. Where no appropriate antivenom exists, supportive care is the treatment — and it is effective.Doctor / Nurse
• Anaphylaxis to a sting: adrenaline FIRST, before any antihistamine or corticosteroid — 1:1000 IM into the anterolateral thigh: adult 500 micrograms (0.5 mL); under 6 years 150 micrograms; 6–12 years 300 micrograms; over 12 years 500 micrograms; repeat every 5 minutes if no improvement. Lie flat with legs elevated (never allow standing), oxygen 15 L/min via reservoir mask, crystalloid 500–1000 mL (child 20 mL/kg) repeated as required. Never an undiluted IV adrenaline bolus. Remove an embedded honeybee stinger immediately — scrape it off; speed matters more than technique.
• Atropine only for dangerous bradyarrhythmia: 0.6 mg IV repeated to a maximum of 3 mg (adult); 20 micrograms/kg IV, minimum single dose 100 micrograms (child). Given indiscriminately in the adrenergic phase it aggravates tachycardia and hyperthermia — and atropine reverses organophosphate poisoning but worsens scorpion storm, so tell them apart first.Doctor / Nurse