title: Clinical predictors for biphasic reactions in children presenting with anaphylaxis.
abstract: BACKGROUND
  One of the main reasons for hospital admission once a child has been stabilized following anaphylaxis is to monitor for a biphasic reaction. However, only a small percentage of anaphylactic episodes involve biphasic reactions that would benefit from admission. Identification of predictive factors for a biphasic reaction would assist in determining who may benefit from prolonged observation.
  
  
  OBJECTIVE
  To determine predictive factors for biphasic reactions in children presenting with anaphylaxis.
  
  
  METHODS
  This was a retrospective study of children presenting with anaphylaxis to a major paediatric emergency department over a 5-year period.
  
  
  RESULTS
  There were 95 uniphasic (87%), 12 (11%) biphasic and two protracted reactions (2%). One child with a protracted reaction died. For the management of the primary anaphylactic reaction, children developing biphasic reactions were more likely to have received >1 dose of adrenaline (58% vs. 22%, P=0.01) and/or a fluid bolus (42% vs. 8%, P=0.01) than those experiencing uniphasic reactions. The absence of either factor was strongly predictive of the absence of a biphasic reaction (negative predictive value 99%), but the presence of either factor was poorly predictive of a biphasic reaction (positive predictive value of 32%). All biphasic reactors, in which the second phase was anaphylactic, received either >1 dose of adrenaline and/or a fluid bolus.
  
  
  CONCLUSIONS
  Children who received >1 dose of adrenaline and/or a fluid bolus for treatment of their primary anaphylactic reaction were at increased risk of developing a biphasic reaction.
authors.affiliation: Department of Allergy and Immunology, Royal Children's Hospital, Melbourne, Australia.
authors.forename: S
authors.initials: S
authors.lastname: Mehr
authors.forename: W K
authors.initials: WK
authors.lastname: Liew
authors.forename: D
authors.initials: D
authors.lastname: Tey
authors.forename: M L K
authors.initials: ML
authors.lastname: Tang
mesh_terms: D000293:Adolescent; D000322:Adrenergic Agonists / Q000008:administration & dosage; D000707:Anaphylaxis / Q000401:mortality / Q000503:physiopathology* / Q000628:therapy; D002648:Child; D002675:Child, Preschool; D004837:Epinephrine / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D012189:Retrospective Studies
chemical_list: D000322:Adrenergic Agonists; D004837:Epinephrine