UMEM Educational Pearls

Title: I just gave IM Epi for anaphylaxis, how long do I need to observe the patient?

Category: Critical Care

Keywords: epinephrine, im, anaphylaxis, allergic reaction, observation (PubMed Search)

Posted: 7/29/2014 by Feras Khan, MD
Click here to contact Feras Khan, MD

Observation after giving IM Epi for allergic reactions or anaphylaxis

Background

Common practice is to observe patients who receive epinephrine for allergic reactions or anaphylaxis for several hours post-administration
This can be from 4-24 hours depending on the institution
This is to monitor for a biphasic reaction

Question

Do we need to observe these patients?
And if so, for how long?

Meta-analysis

2 urban Canadian EDs
5 year period
Primary outcome was the amount of patients with a clinically important biphasic reaction
Secondary outcome was mortality

Results

2819 encounters: 496 anaphylactic + 2323 allergic reactions
5 clinically important biphasic reactions (0.18%; 95% CI 0% to 0.17%)
No fatalities
Biphasic reactions tended to happen several hours (>24hrs) after ED discharge

Limitations

If patients did not return to an ED in the region, then they would not be identified as a possible biphasic reaction

What to do?

You can probably discharge most patients whose symptoms have resolved without a prolonged observation period (<4hrs)
Patients with ongoing anaphylaxis and allergic reaction, should be observed longer or admitted
Biphasic reactions are very rare

References

Grunau B, et al. Incidence of Clinically Important Biphasic Reactions in Emergency Department Patients with Allergic Reactions or Anaphylaxis. Annals of Emergency Medicine. Vol 63, No 6; June 2014 736-743.