To the Editor:
The article reviewing anaphylaxis and anesthesia1is a useful timely reminder of a serious problem that may arise with any of us during anesthesia. I agree that the basic treatment should focus on intravenous (IV) epinephrine and expansion of intravascular volume. However, there is one aspect of this treatment that is misleading. The early administration of epinephrine is emphasized and the dose adjusted to the hemodynamic response, but for severe reactions a single IV bolus and infusion is suboptimal, because it may be slow to achieve the desired effect. Basic pharmacology teaches that the dose–effect relationship of a drug is log-linear and so the titration should be done in a logarithmic fashion. This is most easily done by doubling the amount of epinephrine in each progressive dose until the desired effect is achieved. Commencing with 100 μg IV epinephrine and administering a dose every 2 min as suggested, if the doubling is used, a 3-mg dose of epinephrine, if required, is reached in 8 min. If a 3 mg IV dose is required, the 200 μg epinephrine bolus and 4 μg/min infusion would take over 10 h! When an anaphylaxis occurs, it is not always obvious whether it is a grade III or IV reaction. Early progressive titration of the IV epinephrine will achieve an optimal dosing in the shortest time.
Royal Adelaide Hospital, North Terrace, Adelaide, South Australia. email@example.com