Systemic antivenom and skin necrosis after green pit viper bites

Abstract

Introduction. As systemic effects of viper venoms can be neutralized by antivenom, local tissue damage, particularly necrosis of the skin, has become a more significant problem. The goal of this study is to evaluate the effectiveness of antivenom in preventing dermatonecrosis in envenomated patients with severe coagulopathy. Methods. Retrospective review of medical records of patients who were envenomated by green pit vipers (Trimeresurus albolabris or T. macrops) following bites on fingers or toes and who came to Chulalongkorn hospital from 1996 to 2006. Results. 1,886 records of suspected green pit viper bite patients were reviewed: 243 cases fit the inclusion criteria; 1,643 cases were excluded: uncertain diagnosis (931), bites at other sites (508), inadequate follow-up (196), and necrosis on presentation (8 patients). One-third of the 243 study cases (80 patients) received green pit viper F (ab')2 antivenom an average of 21 hours after envenomation for the treatment of severe coagulopathy. The other 163 study patients were treated symptomatically. After a 3-day follow-up, the percentage of patients who developed gangrene among those who received antivenom (7 of 80 patients) was 8.8% and the percentage of patients who developed gangrene among those who did not receive antivenom (12 of 163 patients) was 7.4 % (p = 0.9). Conclusion. Dermatonecrosis occurs after the systemic administration of antivenom. Earlier administration of antivenom and other treatment modalities should be explored in a prospective study.