China
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Viperidae Snakebite Envenomation
Published in Stephen M. Cohn, Matthew O. Dolich, Kenji Inaba, Acute Care Surgery and Trauma, 2016
Steven Granger, Ronald Stewart
In the United States, absolute indications for antivenom administration have not been rigorously studied or established. Envenomation severity scores have been published that attempt to classify the severity of pit viper envenomation as a guide to directing therapy. These are often based on local, systemic, laboratory, and organ system involvement with some authors advocating no treatment in asymptomatic patients, as up to 25% of confirmed bites may be avenomous [1,6]. Most cases of pit viper envenomation are associated with minimal morbidity, which ultimately may not warrant antivenom administration [32]. Approximately 7%–13% are classified as severe, including those with early presentation of life-threatening symptoms [33]. The venom from copperheads is the least potent U.S. pit viper venom relative to rattlesnake and water moccasin venom. Several authors have published their experiences with conservative management of select pit viper snakebites and specifically mildly symptomatic copperhead envenomations (Level IV evidence) [6,30–32,34–36]. Crotalidae polyvalent immune Fab (ovine) (CroFab; FabAV) is the antivenin of choice [37–43]. This product is safer and very likely more effective than the older equine-based polyvalent antivenin.
Predictors of FabAV use in copperhead envenomation
Published in Clinical Toxicology, 2022
Fatima Ramirez-Cueva, Adam Larsen, Elise Knowlton, Kelsey Baab, Robin Rainey Kiehl, Amy Hendrix, Michelle Condren, Megan Woslager
In October 2000, the FDA approved the use of ovine-derived Crotalidae polyvalent immune Fab anti-venom [8]. Initially, copperhead snakebites were excluded from FabAV clinical trials for several reasons including lack of copperhead bites at the study sites, FabAV cost, less severe or self-limited envenomation, along with concerns for drug toxicity [7,9–19]. FabAV’s safety was later established in copperhead envenomation; however, its use is not entirely benign. Approximately 5% of patients experience an adverse event related to FabAV dosing including skin reaction (pruritic rash, urticaria, angioedema), gastrointestinal and respiratory symptoms, and/or hypotension [20–24]. Some randomized controlled trials of FabAV use in copperhead victims have shown benefit to its use, specifically lower pain scores, reduced limb disability and faster limb recovery with early administration [22,24–27]. These factors have led to conflicting practices regarding the administration of FabAV in copperhead envenomation [7,14,15,28]. The current unified treatment guideline for Crotaline envenomation in the United States attempts to reduce variation in care through evidence-informed guidelines but does not offer guidelines based specifically on identified snake species [29].
Cottonmouth snake bites reported to the ToxIC North American snakebite registry 2013–2017
Published in Clinical Toxicology, 2020
K. Domanski, K. C. Kleinschmidt, S. Greene, A. M. Ruha, V. S. Bebarta, N. Onisko, S. Campleman, J. Brent, P. Wax
Antivenom treatment with Crotalidae Polyvalent Immune Fab (Fab AV; CroFab) was used in 26 patients (84%). A median of 10 vials was used per case (range 1–28). Median time to antivenom administration was 3.5 hours (range 1–29). Three patients received an initial bolus dose of antivenom (range 1–6) but were not treated with maintenance therapy. Frequency of antivenom use did not increase over the four-year study period. Three patients received empiric or prophylactic antibiotics, and one patient underwent fasciotomy for a bite involving the index finger with swelling beyond two major joints for suspected but unconfirmed compartment syndrome. Compartment pressures were not performed. Nineteen patients (61%) were hospitalized for >24 hours. All patients were discharged within 72 hours.
Misidentification of copperhead and cottonmouth snakes following snakebites*
Published in Clinical Toxicology, 2018
Robert D. Cox, Christina S. Parker, Erin C. E. Cox, Michael B. Marlin, Robert L. Galli
Because of the relatively benign clinical course of copperhead bites, these bites have often been treated with only supportive care and observation and not treated with antivenom. Numerous authors have recommended that copperhead bites generally do not require treatment with antivenom [8,9,1312-14]. Prior to 2000, the only antivenom available for treatment of pit viper bites in the United States was Antivenin (Crotalidae) Polyvalent, equine origin (Wyeth-Ayerst, Marietta, PA). This product contained whole IgG immunoglobulin and allergic reactions and serum sickness were major safety concerns with this treatment. Currently, the only antivenom commercially available in the United States is Crotalidae Polyvalent Immune Fab, ovine origin, (CroFab®, BTG International Inc. West Conshohocken, PA). This is a cleaved antibody product containing only Fab IgG fragments. It is much less immunogenic than the previous whole equine product. Crotalidae polyvalent immune Fab (ovine), was prepared with venom from the cottonmouth snake (Agkistrodon piscivorus) as one of the four components, but not venom from the copperhead snake (Agkistrodon contortrix).