A retrospective study of epinephrine administration for anaphylaxis: How many doses are needed?

The precise amount of epinephrine needed to reverse severe symptomatology d ue to an anaphylactic reaction is unknown. We tried to determine how freque ntly more than one injection of epinephrine is required to treat an anaphyl actic reaction. A retrospective review of patient charts with anaphylactic reactions requiring epinephrine, in response to inhalant allergen and hymen optera venom immunotherapy as well as live hymenoptera stings, examined typ e of reaction; number, doses, and timing of epinephrine administered; and a ncillary treatment. A total of 105 anaphylactic reaction events of varying severity (Ring's classification) were recorded (54 - Grade I, 29 - Grade II , 18 - Grade III, a - Grade IV, 4 - unknown). The median epinephrine dose a dministered was 0.3 cc (range 0.1 to 0.8 cc, I:1000). The timing of the fir st epinephrine injection was less than or equal to 5 minutes in 27, 6-10 mi nutes in 13, 11-30 minutes in 16 less than or equal to 30 minutes in 32, 31 -60 minutes in 12, and >60 minutes in five epinephrine treated patients. Ov erall, 38 patients (35.5%; CI95, 26.4-44.6%) required >1 epinephrine inject ion. Of these, 11 experienced Grade I (11/54-20.3%; C195, 9.6-31.0%), 12 - Grade II (12/29-41.5%, C195, 23.5-59.3%), and 13 - Grade III (13/18-72.2%, C195, 51.5-92.9%); reactivity was unknown in 2 patients. Forty-four patient s also received an antihistamine, 10 received corticosteroids, and 30 recei ved both medications and/or other ancillary therapy. A significant number o f patients (>35%) with anaphylactic reactions received greater than one epi nephrine dose to manage events far the three classes of severity. Patients at risk for anaphylaxis and their caregivers need to recognize that more th an one close of epinephrine may be required for treatment of anaphylaxis.