Podcast #226: Biphasic Anaphylaxis

Author: Sam Killian, M.D.

Educational Pearls

• Anaphylaxis is common in the ED. These patients are treated and then usually watched for 4-6 hours.
• Biphasic happens in patients that have a complete resolution of their anaphylaxis  for at least an hour, but then have a recurrence that requires pharmacologic  intervention. Most of the time this happens 3-6 hours later, but can happen more than 10 hours later.
• More commonly happens in patients that have a delayed presentation,  a wide pulse pressure, need multiple doses of epi, require the use of  a beta agonist, or are ages 6-9 years old.
• Educate patients about the possibility of Biphasic anaphylaxis before discharge. 

References: http://www.medscape.org/viewarticle/583328_7