Citation

Ruha AM, Curry SC, Albrecht C, Riley B, Pizon A. Toxicon 2011; 57(1): 53-59.

Affiliation

Department of Medical Toxicology, Banner Good Samaritan Medical Center; Department of Emergency Medicine, Maricopa Medical Center; and Phoenix Children's Hospital, Phoenix, Arizona, United States; Department of Emergency Medicine, University of Arizona College of Medicine, United States.

Copyright

(Copyright © 2011, Elsevier Publishing)

DOI

10.1016/j.toxicon.2010.09.014

PMID

20920516

Abstract

BACKGROUND: North American rattlesnake envenomations commonly produce defibrination, coagulopathy and/or thrombocytopenia, which may be reversed following treatment with Crotalidae Polyvalent Immune Fab Ovine (FabAV). Despite initial resolution with FabAV, late onset or recurrence of venom-induced hematologic effects may occur. Time at which onset of late hematotoxicity may first be detected is unknown. The purpose of this study was to identify the incidence and time of onset of recurrent or new late hypofibrinogenemia, coagulopathy, or thrombocytopenia in a cohort of rattlesnake envenomation patients seen in outpatient follow-up after treatment with FabAV, and to report hematologic outcomes in these patients. METHODS: Review of 66 charts of patients with rattlesnake envenomation who were treated with FabAV, and subsequently had out-patient follow up evaluation at least 48 hours after last FabAV, was performed. Demographic information, rattlesnake and bite characteristics, dose and timing of antivenom administration, adverse events, in-patient laboratory values, length of hospital stay, and follow up laboratory values were collected.The primary outcome parameters were recurrent or delayed onset coagulopathy, hypofibrinogenemia, or thrombocytopenia identified no sooner than 48 hours after last dose of FabAV. Results: Prior to control of the envenomation with FabAV, 42 patients (63.6%) experienced hematologic toxicity. At follow up, 21 patients (32%) were found to have late coagulopathy, hypofibrinogenemia, or thrombocytopenia. Of twenty-three patients (35%) with more than one follow-up visit, fifteen had normal laboratory findings at the first follow up visit. Five of these 15 patients (8% of total study group; 33% of this subgroup) with normal hematologic studies at first follow-up exhibited late hematologic toxicity at second follow up. Severe late hematologic toxicity developed in five of 66 (8%) patients. One patient was retreated with FabAV for late severe thrombocytopenia. Conclusion: Recurrent and delayed onset of hematologic toxicity in rattlesnake envenomation victims treated with FabAV is common. Follow-up more than three days after treatment is necessary to detect all cases of late hematologic toxicity.

Language: en