Rattlesnake envenomation can result in significant cutaneous and hematologic toxicity. While Cotalidae polyvalent immune Fab (ovine) antivenom (marketed as CroFab) was available for years, it is associated with increased late hematologic toxicity compared with its predecessor. Consequently, Crotalidae Immune F(ab’)₂ equine antivenom [marketed as Anavip; F(ab’)₂AV] has been recently become available. In this paper, we report a case of a 53 year-old man envenomated on his right hand by a Southern Pacific rattlesnake (Crotalus helleri). Edema was present, and his initial platelets were not able to be measured, prompting the administration of 10 vials of F(ab’)₂AV. Ultimately, he received a total of 52 vials of antivenom, before his platelets peaked at 102,000/μL, 56 hours post envenomation. Within hours, his platelets began to fall again. Ultimately, his platelets reached a post-antivenom nadir of 65,000/μL. He was observed closely as an outpatient without additional antivenom, and ultimately had normalization of his platelets (211,000/μL) 20 days post envenomation. This case is one of the first cases demonstrating an inability to achieve control of the hematologic toxicity following Southern Pacific rattlesnake envenomation after treatment with F(ab’)₂AV.

响尾蛇的毒液可导致严重的皮肤和血液毒性。虽然 Cotalidae 多价免疫 Fab（绵羊）抗蛇毒血清（以 CroFab 名义销售）已上市多年，但与前身相比，它与晚期血液毒性增加有关。因此，Crotalidae Immune F(ab') ₂马抗蛇毒血清 [以 Anavip 名义销售； F(ab') ₂ AV] 最近已推出。在本文中，我们报告了一名 53 岁男子右手被南太平洋响尾蛇 ( Crotalus helleri ) 毒害的案例。由于存在水肿，并且无法测量他最初的血小板，因此需要注射 10 瓶 F(ab') ₂ AV。最终，他总共接受了 52 瓶抗蛇毒血清，在中毒后 56 小时，他的血小板达到了 102,000/μL 的峰值。几个小时后，他的血小板再次开始下降。最终，他的血小板达到了抗蛇毒血清注射后的最低点 65,000/μL。在门诊时对他进行了密切观察，没有额外使用抗蛇毒血清，最终在中毒后 20 天他的血小板恢复正常（211,000/μL）。该病例是第一批证明用 F(ab') ₂ AV 治疗后无法控制南太平洋响尾蛇中毒后血液毒性的病例之一。