Crotaline Fab antivenom for the treatment of children with rattlesnake envenomation

Objective. There is little data regarding safety or efficacy of Crotalinae polyvalent immune Fab (ovine) antivenom (crotaline Fab) in pediatric patients. Our objective was to provide the first information regarding safety and effectiveness of this new drug in children. Methods. Data were collected prospectively and retrospectively for all consecutive pediatric patients bitten by rattlesnakes and treated at 2 urban hospitals during 2001. Cases were included if there were signs of envenomation at presentation, patient age was 13 years or less, and there was administration of crotaline Fab. Cases were excluded if antivenin (Crotalidae) polyvalent (equine origin, the conventional antivenom) was given. Primary outcome variables were snakebite severity scores throughout the course of therapy, number of vials of crotaline Fab administered, occurrence of allergic reactions, adjunct surgical therapy, and the presence of permanent sequelae or serum sickness identified at follow-up. Results. In the 12 cases studied, ages ranged from 14 months to 13 years (mean: 6.9; standard deviation: 4.2). Presentation snakebite severity scores ranged from 2 to 9 (mean: 5.3; standard deviation: 2.3). Total crotaline Fab doses ranged from 4 to 22 vials (mean: 12.7; standard deviation: 5.4). Initial control of symptoms was achieved with 4 to 16 vials (mean: 7.7; standard deviation: 3.7), and severity scores stabilized or improved within 24 hours in all patients. Recurrence of local swelling occurred in 1 case despite scheduled repeat doses of antivenom. No cases required surgical intervention, and no permanent sequelae were identified. No immediate or delayed hypersensitivity reactions occurred. Conclusion. In this group of pediatric patients treated for rattlesnake envenomation, crotaline Fab antivenom was safe and seemed to be effective.