title: Factors associated with difficulty achieving initial control with crotalidae polyvalent immune fab antivenom in snakebite patients.
abstract: BACKGROUND
  The prescribing information for Crotalidae Fab antivenom (FabAV) instructs clinicians to administer FabAV until initial control of the envenomation syndrome is achieved. Risk factors for difficulty achieving initial control are not known.
  
  
  OBJECTIVE
  The study aim was to identify factors present before administration of antivenom associated with difficulty achieving initial control.
  
  
  METHODS
  The authors conducted a retrospective study of all patients presenting to any one of 17 centers and receiving FabAV from 2002 to 2004. Demographic and historical information, as well as data about nine specific venom effects, were collected prior to the administration of antivenom. An expert panel used standard criteria to determine if initial control was achieved. The patient group that had difficulty achieving initial control was compared to the group that achieved initial control, and adjusted odds ratios were calculated using stepwise logistic regression.
  
  
  RESULTS
  A total of 247 patients were included in the final analysis. The majority of patients were envenomated on the upper extremity and were young males. A total of 203 patients (82.2%) achieved initial control. In univariate analysis, thrombocytopenia, bleeding, neurologic effects, and a severe bite were significantly associated with difficulty achieving initial control. After logistic regression, the presence of neurologic effects and thrombocytopenia remained significantly associated with difficulty achieving initial control. When both factors were present, the patient was 13.8 times more likely to have difficulty achieving initial control.
  
  
  CONCLUSIONS
  A number of factors were present before the administration of FabAV that were independently associated with difficulty achieving initial control of the envenomation syndrome. Predicting which patients will have difficulty achieving initial control has important ramifications for patient disposition and may provide insight into the mechanisms for lack of antivenom efficacy.
authors.affiliation: Denver Health Hospital Authority, Rocky Mountain Poison and Drug Center, Denver, CO, USA. shan1yin@gmail.com
authors.forename: Shan
authors.initials: S
authors.lastname: Yin
authors.forename: Jamie
authors.initials: J
authors.lastname: Kokko
authors.forename: Eric
authors.initials: E
authors.lastname: Lavonas
authors.forename: Sara
authors.initials: S
authors.lastname: Mlynarchek
authors.forename: Greg
authors.initials: G
authors.lastname: Bogdan
authors.forename: Tammi
authors.initials: T
authors.lastname: Schaeffer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000997:Antivenins / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007140:Immunoglobulin Fab Fragments; D007128:Immunoglobulin Fragments / Q000627:therapeutic use*; D007223:Infant; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D012909:Snake Bites / Q000150:complications / Q000188:drug therapy*; D016896:Treatment Outcome; D014481:United States; D055815:Young Adult
chemical_list: D000997:Antivenins; C431183:Crotalidae Polyvalent immune Fab; D007140:Immunoglobulin Fab Fragments; D007128:Immunoglobulin Fragments