We are usually observing patients in emergency department in length due to biphasic reaction. There are 2 articles published during last 6 months and they emphasized regarding of how common is biphasic reaction and mortality of this reaction!
The first one published in annals of EM in Nov 2013 tiltled: “Incidence of Clinically Important Biphasic Reactions in Emergency Department Patients With Allergic Reactions or Anaphylaxis“. Their objective was questionable rate of bipasic reaction and also prolong ED LOS. They Reviewed 2,819 patients, 496 anaphylactic and 2,323 allergic reactions. among these 185 patients returned at least 1 time to ED related to allergic complaints. among these 5 had significant biphasic reactions. 2 of anaphylaxis group(496) happened in ED(16, 200 min), and 3 among allergic reaction(2323). none happened in ED. almost 6 % returned to ED with related “allergic” symptoms. Their conclusion is biphasic reaction and fatality are rare and it is not necessary in simple, uncomplicated cases to observe patient in length in ED.
The Second study was published in Allergy Apr. 2014. The objectives are the rate of biphasic – andit’s importance and anaphylactic reactions, transfers to ICU, and deaths within 10 days of presentation to the ED. Study Period from 2001 to 2013. From 1334, 532 allergic reaction and 495 patients had anaphylactic reaction. In 227 (44.8%) the LOS was ≥8 h. 507 uniphasic and 25 (4.5%) biphasic. 12 (2.3%) were clinically important, including 2 (0.36%) that occurred during hospital stay, one of whom (0.19%) was transferred to ICU for shock. No risk factors for biphasic reactions could be found. No death within 10 days. Their conclusion is “to consider discharging patients after complete resolution of an anaphylactic reaction and to dispense with prolonged monitoring”.