Prazosin therapy and scorpion envenomation

Abstract

Background: 25-30% fatality due to acute pulmonary oedema in victims of Indian red scorpion (Mesobuthus tamulus) sting have been reported from Western Maharashtra, India. The advent of prazosin in recent years has revolutionized the management of severe scorpion sting cases. Majority of cases developed acute pulmonary oedema in 4-8 hours in a hospital setting irrespective of control of their arterial blood pressure with six hourly oral prazosin regimen, these cases recovered with extra dose of prazosin. We developed a standardised protocol for acute phase of treatment of these cases with the aim of preventing the development of pulmonary oedema.

Method: We compared scorpion sting cases managed by non-protocol conventional (NPC) treatment and those by standardised protocol (SP) that included three hourly dose of oral prazosin. SP group included severe scorpion sting cases admitted to general hospital at Mahad in the year 1998 (Jan.-Dec.). While those admitted in the year 1997 (Jan.-Dec.) before the SP was implicated were the NPC group.

Finding: Characteristics on arrival of severe scorpion sting patients SP (n-17) and NPC (n-15) groups were similar that more case 6 (35%) from SP group had several hypertension on arrival. On arrival two cases from SP group and one from NPC group had pulmonary oedema. 16 (94.11%) patients from SP group recovered uneventfully, compared with 8 (53.33%) in NPC group (p-0.05). 0% Vs 5 (38.46%) developed acute pulmonary oedema (p < 0.0001) from SP and NPC group respectively, three (one had on arrival two patients during hospitalization) from NPC group had massive pulmonary oedema recovered with i.v. nitroprusside drip (SNP). While from SP group one had massive pulmonary oedema on arrival recovered with i.v. SNP, other one had pulmonary oedema recovered with oral prazosin. Cool extremities (vasoconstriction) persisted 11.5 (5-20) VS 18 (12-26) hours in SP and NPC group respectively.

Interpretation: Compared with NPC management; development of acute pulmonary oedema prevented by standardised protocol regimen at rural setting.