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Page 1 of 3 Vasodilation
Vasodilators: Scorpion envenoming and the heart
(An Indian Experience)
(Received for publication 11 March 1994)
Our aim was to assess clinically whether there was any benefit in adding a single dose of sublingual nifedipine (a slow calcium channel blocker) to prazosin in the management of the cardiovascular manifestations of envenoming by the Indian red scorpion (Mesobuthus tamulus). A total of 163 patients stung by this species was admitted to the hospital at Mahad between January 1991 and October 1993.
Cardiovascular abnormalities were hypertension (59), of whom 42 had brady cardia and 17 had tachycardia, pulmonary oedema (14), of whom eight had hypertension and six hypotension, supraventricular tachycardia (eight), of whom three had hypotension and one died. Of the remaining patients, 78 demonstrated severe excruciating local pain at the site of sting but had no systemic involvement. Nineteen patients with hypertension and tachycardia were given a single dose of sublingual nifedipine plus prazosin on admission, then prazosin alone repeated 6 hourly. Five patients with massive life threatening pulmonary edema recovered after being given intravenous sodium nitroprusside. Prazosin alone helped to alleviate cardiovascular manifestations in the remaining 42 victims.
One patient was admitted in a deep coma, 12 hr after the sting, and died. Eight victims whose blood pressure had been controlled in hospital by nifedipine plus prazoin for recovery. Fifty two victims treated with prazosin alone did not develop pulmonary edema and the drug appeared to hasten the recovery. In the presence of high blood pressure, tachycardia, a murmur and impending myocardial failure, nifedipine appeared to contribute to cardiopulmonary instability and to augment myocardial oxygen consumption. In this situation calcium channel blockers should probably be avoided.
Introduction
Scorpion envenoming is common in many parts of the world (Amitai et al., 1984, Poonking, 1963, Gueron et al., 1967, Mundle, 1961). Primary health where medical aid is first sought by villagers deal with the largest number of cases (Gaitonde et al.,1978, Bawaskar and Bawaskar, 1989). Envenoming by Mesobuthus tamulus has a fatality rate of 30 to 54% (Mundle, 1961, Bawaskar, 1977, Rajarajeswari et al., 1979, Karnad et al., 1989). These accidents usually occur during the night because scorpions are nocturnal. For medical help, villagers have to travel 10 to 20 miles or more. As cardiovascular morbidity and mortality depends upon the time lapse between sting and hospitalization (Bawaskar and Bawaskar, 1991), we believe that the delay in transport of these patients to the nearest large hospital contributed to their death (Bawaskar, 1982). We would stress the importance of the cardiotoxic effects of scorpion sting and their pharmacological management within the limited resources available in health centers.
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