Management :

No sting should be taken as benign unless observed for 24 hours irrespective of species of scorpion involved.

Local pain
Cut at the sting site and tourniquet is not advisable.
Mild, tolerable pain can be abolished by application cold or ice packs over the site of sting. Severe excruciating pain is transiently relieved by local anesthesia xylocaine without adrenaline. Repeated injections of local anesthesia are often required for pain relief. It is observed that the reappearance of pain after initial local xylocaine is much severe than what was before the first injection. This is because of rapid tolerance to xylocaine and repeated injection stimulates the inflammation and in an inflamed tissue the action of xylocaine is blunted. Hence simultaneously oral diazepam and NSAID with first initial dose of xylocaine can give prolonged relief of pain. However injection of emetine hydrochloride exactly at the site of sting gives prolonged relief from pain, but it is not available and moreover it is cardiotoxic and one need to be careful while injecting because sting is often over the thick skin of sole and many times while injecting it the drug may suddenly be flushed back due to dislodged needle and piston from syringe and enter in the eyes of a person injecting it. Being severe tissue irritant, it causes corneal edema and irritating injury to cornea (author himself suffered of this).

Correction of dehydration
Dehydration due to vomiting, excessive salivation, and profuse sweating should be corrected by continuous vigorous oral rehydration solution. This helps to correct initial hypotension and shock. Intravenous crystalloid solution or hydration by nasal tube may be necessary in a confused, agitated child. Fluid replacement must be corrected since hypovolemia is one of the proposed mechanisms of shock syndrome in scorpion sting. Electrolytes imbalance should be corrected. Calcium can be replaced by encouraging excessive milk consumption. Grape juice may be avoided as it may enhance the prolonged the QTC interval

Scorpion antivenin
Scorpion antivenin is available in India. Though it is specific antidote to venom action but in case of mesobuthus tamulus sting antivenin, it does not prevent or reverse the cardiovascular morbidity and mortality. Moreover it is not free from anaphylaxis. The half-life time of antivenin is longer than venom. In animals no beneficial effects of antivenin are observed if it is injected more than 15 minutes after injecting the venom. It does not counteract the venom induced autonomic storm. In our series, mesobuthus antivenin did alleviate the cardiovascular morbidity and mortality. 21 severe scorpion sting cases aging 3-56 (average22) years were reported within 30 minutes to 21 hours (average 3.5) after sting. All of them had clinical manifestations suggestive of autonomic storm. They received scorpion antivenin by intravenous route and were closely observed for clinical outcome. Out of these, 12 had persistent raised blood pressure, 8 developed pulmonary edema, of which 2 had massive life threatening pulmonary edema, 1 had hypotension with tachycardia and 2 died. Recently it has been reported that scorpion antivenin is no better than placebo. Venom is poor antigen hence it is difficult to prepared potent antivenin. Scorpion venom acts indirectly by releasing auto-pharmacological substance in to circulation.

Prazosin
Alpha-receptors play vital role in the pathogenesis of cardiac failure and pulmonary edema due to scorpion sting. Prazosin is a selective alpha -1 adrenergic receptor blocker. It dilates veins and arterioles, there by reducing pre-load and left ventricular impedance without rise in heart rate and renin secretion. It also inhibits sympathetic outflow in central nervous system. It is phospodiesterase inhibitor and as a result of this action it enhances cGMP accumulation, which is one of the mediator of nitric oxide synthesis. It enhances insulin secretion, which is inhibited by venom action. Thus its pharmacological properties can antagonize the haemodynamic, hormonal and metabolic effects of scorpion venom action. It can be administered by oral route. Prazosin is simple, scientific pharmacological and physiological antidote to scorpion venom actions; moreover it is free from anaphylaxis.

Prazosin should be given in a dose of 125-250 microgram in children and 500 microgram in adults and should be repeated three hourly until there are signs of clinical improvement in tissue perfusion such as warming of extremities, increase in urine output, appearance of severe local pain at the site of sting which was absent or tolerable on arrival, disappearance of paresthesia, reduction or improvement in heart rate and pulmonary edema, reduction in hypertension or improvement in blood pressure in case of hypotension without hypovolemia, reduction or disappearance of murmur and earliest most important subjective feeling of better. This is because the drug has 1000 times affinity towards the activated alpha-1 receptors. Then dose is to be repeated six hourly till extremities became dry and warm. If the initial dose has been vomited (one should see the vomit carefully), it should be repeated. In a confused, agitated, non-cooperative child, prazosin should be administered by nasal tube after giving intravenous diazepam

Prazosin is life saving drug hence attending doctor himself should administer the drug to the hospitalized patient and he should clinically confirmed by noting the signs and symptoms that drug is absorbed in circulation and started acting.

First dose phenomenon is rare or avoided by administering minimum initial dose of prazosin. However due care should be taken to avoid postural fall in blood pressure. Children should not be lifted. Postural hypotension should be treated by giving head low position and intravenous fluid.

Pulmonary edema :

Is a life threatening time limiting emergency often fatal and needs rapid intervention. Patient should be given propped up position, intravenous aminophylline 5mg/kg diluted in dextrose given as a slow bolus to counter the associated bronchospasm. If available isosorbide buccal spray is useful or powder of nitroglycerine should be rubbed on gum and intravenous furosemide 10-20 mg should be given to reduce the preload and pulmonary congestion. In a case of massive pulmonary edema (blood stained froth from nostrils and mouth), intravenous sodium nitroprusside (SNP) drip 3-5 microgram per kg per minute can be started and dose should be raised continuously according to patient's response and blood pressure. Blood pressure should be closely monitored and maintained at the level of systolic 80-90 mm hg. SNP has to be prepared from fresh powder every four hours; the bottle and saline set should be protected from light. At times a severe case may required 15-36 hours of SNP drip to clear pulmonary edema. Patient should be given oral or injectable cyanocobalamin to avoid cyanide toxicity whenever SNP is given for long time. Before starting SNP, IV furosemide is given to avoid sudden fall of intra-ocular pressure and ocular bleed due to SNP drip. IV nitroglycerine can be used 5-8 microgram per minute if SNP is not available. In case of shock or hypotension early administration of dobutamine 5-15 microgram per kg per minute along with SNP drip may be life saving. In children, after 20-24 hours of sting, marked tachycardia (130 and above), warm extremities, pulmonary edema or air hunger respond to IV dobutamine drip, which may be required for 48 hours.