A scorpion sting may be a benign sting or a fatal envenomation. Confirmation of the sting is done by history given by an eye witness or by observing a killed scorpion. The victim presents with mild to severe acute onset local pain with local oedema, sweating, fasciculation / spasm of the bitten part, with local urticaria and a positive TAP (hyperesthesia on tapping) sign. Some features help in differentiating benign from a life threatening sting.
Non poisonous or benign sting:
It is characterized by severe local pain, local sweating, mildly raised blood pressure and absence of autonomic storm.
Poisonous envenomation:
Soon after a sting, of autonomic storm are seen. They are characterized by vomiting, profuse sweating (skin diarrhea), cold extremities, excessive salivation (ropy salivation), priapism in males, paraesthesia all over and around the mouth, hypertension or hypotension and cardiac arrhythmia. Cardiac examination may reveal sinus bradycardia or tachycardia, S3 gallop, at times transient nonsustained ventricular tachycardia, transient systolic murmur and left ventricular failure. ECG may show premature ventricular contraction, bigeminy, tented T waves, acute myocardial infarction like pattern, ST depression, injury to conducting system i.e., left anterior hemiblock, left or right bundle branch block and QTc> 500 m secs. Anuria and pulmonary edema presenting with cyanosis, hypotension, pinkish froth, convulsions and shock are late manifestations. Some of the other features are oculogyric phenomenon, propped up eyes, puffy face and abdominal colic.
Management:
Non poisonous or benign sting:
Treatment of a benign sting is aimed at pain relief and patients should be given reassurance. For pain relief a local anaesthetic agent could be used and cooling of the affected part is done. Oral paracetamol and oral diazepam may also be used.
Poisonous envenoming: Hospitalization is necessary for stabilization of hemodynamics and frequent monitoring.
Dehydration correction:
Oral rehydration / IV crystalloids Autonomic storm and cardiac failure: Oral prazosin (short acting minipress XL) - 250 microgram for below five year of age and 500 microgram above age of five years is given. It may be repeated every three hours till extremities are cold. Dobutamine (5-15 microgram per kg per minute) drip could be considered in cases of heart failure.
Pulmonary edema: Propped up position, oxygen, intravenous frusemide 20 mg to reduce preload and aminophylline bolus 5 mg/per kg body weight is given in addition to oral prazosin. Massive pulmonary edema characterized by cyanosis, hypotension, pinkish froth may also need nitroglycerine spray or a sub-lingual tablet/sodium nitroprusside drip 3-5 microgram per kg per minute. It is important to note that 10 mg IV frusemide should be administered before starting sodium nitroprusside to prevent intraocular bleed. Clinical response should be monitored to adjust the doses. This supportive treatment is continued until hemodynamic stabilization is achieved.
Fatal complications: Rarely convulsions occur following lethal ventricular arrhythmias. Patients may develop hemiplegia, cerebral infarction which require IV or rectal diazepam.
NOTE: Drugs to be avoided during treatment are atropine, antihistamines, steroids, beta blockers, excessive diuretics, nifedipine, digoxin, adrenaline and narcotics.
|
