Abstract
Short-Term Outcomes after Fab Antivenom Therapy for Severe Crotaline Snakebite
(Ann Emerg Med. 2010 Epub) EJ Lavonas, J Kokko, TH Schaeffer, et al
Prepared by Anil Menon, MD, UTMB/NASA Aerospace Medicine Fellow, Galveston, TX, USA
In 2008 there were 2800 reports of emergency care being sought for crotaline envenomations. Antivenom was given to 60% of these cases. An ovine polyvalent Fab has been available since 2000 (FabAV) while a previous equine Fab has been discontinued. Though it is thought that the ovine Fab carries less risk for hypersensitivity reactions, prior research did not focus on severe envenomations. This multicenter observational case series sought to determine the response to FabAV treatment and define the incidence of hypersensitivity reactions.
The authors retrospectively analyzed crotaline envenomations at 17 hospitals between 2002 and 2004. They documented a severity score similar to the Snake Bite Severity score. The 7-point scale measured tissue effects, cardiovascular symptoms, hematologic effects, respiratory symptoms, lab abnormalities, and other symptoms to categorize bite severity. Hypersensitivity reactions were also noted and reviewed.
During the observational period 247 patients received FabAV with 209 having a complete severity score and 28 having a pretreatment severity score. All patients scored as severe improved after treatment. Of the 247 patients receiving treatment, 6% had a hypersensitivity reaction and 5% serum sickness. Immediate and serious reactions were noted in 4 patients, 1 of whom needed a cricothyrotomy. Hypersensitivity reactions did not depend on disease severity or the number of vials that were required. Though this study is limited by its retrospective design, it is well constructed and provides extensive and detailed information on crotaline envenomations and treatment.