Management of the cardiovascular manifestations of poisoning by the Indian red scorpion (mesobuthus tamulus).
H. S. Bawaskar, P. H Bawaskar
Objective: The efficacy of nifedipine and prazosin in combination or alone in the management of cardiovascular manifestations caused to Mesobuthus tamulus poisoning was investigated.
Design: Observation and study
Setting: Hospital at Mahad, Maharashtra, India.
Subjects: 62 patients who had been stung by a red scorpion were admitted between January.
December 1990: 18 with hypertension, 15 with supraventricular tachycardia, 11with pulmonary edema, and 18 with local pain at the site of sting but no systemic involvement. Two patients with massive life–threatening pulmonary edema were given intravenous sodium nitroprusside.
The combination of nifedipine and prazosin was more successful in preventing myocardial damage in 16 patients with hypertension than was nifedipine alone in two other patients with hypertension. Prazosin alone helped to alleviate the cardiovascular manifestations in eight patients with pulmonary edema and 15 with supraventricular tachycardia. One patient with pulmonary edema died and two recovered after they were given intravenous sodium nitroprusside.
Nifedipine alone did not prevent myocardial damage unless the peripheral action of venom was blocked by prazosin.
Mortality from mesobuthus, formerly buthus or buthotus tamulus stings in the Mahad region was about 30%. We have studied this acute medical emergency since 1976. Our clinical observations and knowledge of the pathophysiology of scorpion stings in humans and dogs led to the use of vasodilators and calcium channel blockers which reduced mortality to 2–3%.
Patients and Methods
Sixty two patients stung by red scorpions (mesobuthus tamulus) were admitted to our hospital. Soon after being stung, 44 patients had vomiting, profuse sweating, hypersalivation, priapism, and mild local pain at the site of the sting that were suggestive of autonomic storm. The other 18 had excruciating pain at the site of the sting that radiated to the adjacent dermatomes but no other signs or symptoms of systemic involvement. Local pain was treated by injecting 0.1–0.2 ml dehydroemetine (0.03%) at the site of the sting. Radiation of pain usually prevents patients from identifying the site, but the sting causes local sweating and a punctuate haemorrhagic spot in subcutaneous tissue or skin resulting from rupture of the capillaries by the sharp sting. The 44 patients with systemic involvement were admitted and the following were closely monitored: Heart rate, blood pressure, persistence of parasternal systolic lift, systolic murmur, gallops, rales, priapism, the appearance of the skin, and the temperature of the extremities, they were divided into three groups with different major clinical features:
- Pulmonary edema.
Eighteen patients had hypertension, loud protodiastolic gallop, a transient apical 2/6 systolic murmur of papillary muscle dysfunction, and systolic parasternal lift. They seemed frightened and had prominent eyes and a puffy face. The children were confused and agitated and looked lethargic. In two patients pulmonary edema subsequently developed.
Supraventricular atrial tachycardia (130–180 beats/min) with fast, thready peripheral pulsations and cold extremities developed in 15 children, 5–7 hours after they were stung. There was an improvement in clinical signs with an increase in tissue perfusion within 6–8 hours of treatment with oral prazosin alone (table). Hypovolaemia was corrected by oral rehydration solution. Agitated, confused and non–cooperative patients were given a 5% dextrose saline drip.
Eleven patients had acute pulmonary edema, tachycardia, cold extremities, ashen gray conjunctivae, tongue and lips and fingers and toes that looked frostbitten because of severe vasoconstriction. Two of these (aged 10 and 25 years) sought help 12 and 4.5 hours after being stung. They had life–threatening massive pulmonary edema and were cyanosed and coughing up pinkish froth through their mouths and nostrils.
A 25 year old man, who was brought in three days after the sting, had right–sided hemiplegia preceded by pulmonary edema. A 2 year girl became unconscious 14 hours after the sting. She had generalized convulsions, pin point pupils that reacted poorly to light, undetectable peripheral pulses and blood pressure, and moist rales. The electrocardiogram showed a heart rate of 215 beats/min, a left anterior hemiblock, a low voltage pattern, and ST segment depression of 5mm in leads V2, V3 and V4.
Sixteen patients with hypertension on admission were given a single dose of 5mg sublingual nifedipine and oral prazosin was repeated six hourly until the extremities were cold. The blood pressure in the remaining two patients with hypertension was controlled with sublingual nifedipine alone; the dose was repeated to control rebound hypertension. Three hours later despite control of arterial pressure pulmonary edema developed in these two patients who recovered after additional treatment with oral prazosin. Patients with tachycardia were treated with prazosin alone and hydration therapy. Those with pulmonary edema were propped up and given intravenous aminophylline, sodium bicarbonate, oral prazosin, and oxygen by mask. Two of these patients had life–threatening massive pulmonary edema. They were treated with an intravenous sodium nitroprusside drip. The patient who died had severe pulmonary edema, tachycardia, convulsions, pin–point poorly reacting pupils, and peripheral circulatory failure. He was treated with intravenous chlorpromazine, aminophylline, sodium bicarbonate, fursemide (to reduce the preload), oxygen by mask, and a 5% dextrose infusion, but he died of a cardiac arrest.