Biphasic anaphylaxis is an anaphylactic episode followed by an asymptomatic period with the return of anaphylactic symptoms in the absence of further exposure to the triggering antigen. The incidence of secondary reaction following primary anaphylactic reaction can range from 1% to 23% and occurs in up to 23% of adults and up to 11% of children. The time interval from primary to secondary reaction ranges from 1 to 72 hours, though predominantly occurs within 8 hours of the primary event.
Epinephrine and other ACLS drugs lead to more patients with ROSC but no increase in the number of patients with good neurologic outcomes after OHCA.
Something that’s very interesting is the actual 2015 ACLS recommendation for epinephrine. It reads, “it is reasonable to consider administering a 1 mg dose of IV/IO epinephrine every 3 to 5 minutes during adult cardiac arrest.” This actually leaves room to not give the medication if the physician thinks it should be withheld.