Delayed administration of Vipera xanthina palaestinae antivenin.

INTRODUCTION: Vipera xanthina palaestinae is the most widely distributed venomous snake in Israel, accounting for most envenomations. A specific equine antivenin is efficacious against both systemic and local manifestations if given within hours. This study sought to determine if delayed vipera xanthina palaestinae antivenin can be effective.
METHODS: Patients who had been bitten by vipera xanthina palaestinae during 1991-1995 were evaluated. Those who continued to deteriorate beyond 24 h post envenomation, in spite of treatment or because of delayed diagnosis, were given vipera xanthina palaestinae antivenin.
RESULTS: Ten patients were included in the study. Vipera xanthina palaestinae was identified in seven and diagnosis was considered probable in three patients. On admission, eight patients had local signs and seven patients had mild to severe systemic manifestations. The local signs were remarkable and progressive in all patients. In five, systemic signs and laboratory abnormalities were delayed as well. The time range for delayed antivenin administration was 1-6 days after envenomation. Following antivenin administration, progression of local signs ceased in all patients and swelling regressed within 24 h. In nine patients this occurred within 6 h.
CONCLUSION: Vipera xanthina palaestinae antivenin administration should be considered in patients with envenomations complicated by marked and progressive local signs, delayed systemic signs and laboratory abnormalities more than 24 h after envenomation.