Scorpion Sting Poisoning
Q. Easy recall “rule of 30” in scorpion stings?
• Out of 1,500 scorpion species known to exist, about “30 are toxic”
• In fatal stings, death occurs “within 30min” due to fatal ventricular arrhythmia.
• “30 hour” observation in Hospital before declaring as dry sting.
• SAV (Scorpion Anti Venim) dose “30ml over 30min” irrespective of patient’s age & weight.
• “30% mortality rate in scorpion stunged victim” reduced to 1% by using Prazosin- Poor man’s SAV.
• Prazosin = “30mcg/Kg” in start, watch for first dose hypotension.
• Dobutamine= “30mcg/kg/min”
• Steroids: Hydrocortisone = “30 mg/kg”, single dose or six hourly up to a total dose of 12 g per day) for correcting refractory shock & ARDS
Q. How many types of scorpion are in India?
Red Scorpion & Black Scorpion.
Q. Which color of scorpion is more poisonous?
“Red is Bad”
Red Scorpion(Mesobuthus tamulus) is more poisonous than black one, and its antidote - antivenom, available in India. But its not easily available & costly ( 1 vial costs Rs 1500). Prazosin is useful as an add-on therapy for M. tamulus stings (cost of 10 tablets = Rs 32)- so prazosin is called as poor man’s scorpion antivenim.
Q. How clinical picture changes within hours of sting toxicity?
5 clinical grade of scorpion sting on arrival at hospital:
Grade 1: severe, excruciating local pain at the sting site radiating along with corresponding dermatomes, mild local oedema with sweating at the sting site, without systemic involvement
Grade 2: signs and symptoms of autonomic storm characterised by acetylcholine excess or parasympathetic stimulation (vomiting, profuse sweating from all over body, ropey salivation, bradycardia, premature ventricular contraction, hypotension, priapism in men) and sympathetic stimulation (hypertension with blood pressure >140/90, tachycardia with heart rate >120 per minute, cold extremities, transient systolic murmur).
Grade 3: cold extremities, tachycardia, hypotension or hypertension with pulmonary oedema (respiratory rate >24 per minute, basal rales or crackles in lungs).
Grade 4: tachycardia, hypotension with or without pulmonary oedema with warm extremities (warm shock).
Q. How to Easy recall Scorpion Sting management?
All S-S-S mnemonic
• S-Sting strikes by scorpion
• S-Shoes & Shirts h (hiding inside)- always careful in villages & forests
• Storehouse & dark crevices
• S-Small red mark- Skin lesion-Severe tenderness
• S-Sudden tap at S-Site of Sting induces S-Severe pain & S-Sudden withdrawl (Tap test positive)- due to serotonin excess released locally.
• S-Sympathomimetic + cholinergic toxidrome
• S-Storm (Autonomic Storm)- transient parasympathetic & prolonged sympathetic.
• Stimulates ANS-Autonomic Nervous system
• S- Slows closing of neuronal sodium channels, resulting in “autonomic storm” owing to S-Sudden pouring of endogenous catecholamine into the circulation
• S-Sinus bradycardia initially, followed by S-Sinus tachycardia persistently
• S-Spasms of limbs & penis (priapism)
• S-Skin Diarrhoea (S-Sweating profusely)
• S-Secretions profuse – oral, tears, nasal
• S-Spontaneous S- Systemic bleeding (defibrination syndrome)
• S-Shock requiring Dobutamine support
• S-Seizure & hyper-excitable state
• S-Suffocation due to cardiogenic pulmonary edema(ARDS)
• S-ST elevation with Q waves due autonomic storm
• S-Systolic murmur
• S-Summation gallops
• S-Stress induced cardiomyopathy & Ballooning syndrome due autonomic storm
• S-Serotonin & Ach excess
• S-Secretions of renin & aldosterone profusely
• S-Sodium channel kept open by toxin- causing Storm of endogenous catecholamines
• S-Sodium nitroprusside & NTG to control hypertension
• S- Serotherapy with scorpion antivenom(SAV)- monospecific F(ab)2
• S-SAV- in S-Severe local envenomation & S-Systemic toxicity
• S-Sedative to control seizure & pain
• S-Synaptic alpha blocker- Prazosin
• S-Steroids - Hydrocortisone 100 mg IV repeated every 4 hours helps to tide over the shock and decreases edema of conductive tissues in toxic myocarditis.
• S-Saline infusion (0.9% Normal saline) to correct hypovolemic & hemorrhagic shock