This Twitter summary from the 2013 meeting of the American College of Allergy, Asthma & Immunology (#ACAAI) was based on tweets by the following allergists/immunologists: Robert Silge, MD @DrSilge
Dr. Ellis @DrAnneEllis
Susan Bailey MD @subailey
DareSiriMD @dar_siri
Highlights of the Practice parameter - do you have the right diagnosis? Avoid the trigger, prescribe epinephrine, give VIT to patients with venom allergy.
How to make the correct diagnosis?
Cutaneous findings are the most common sign of anaphylaxis. "Skin is king" - the most frequent signs of anaphylaxis are cutaneous, but not always. Skin manifestations are often absent during intraoperative anaphylaxis for a variety of reasons. In surgical setting skin findings are less common, either because they are hidden by drapes, or by nature of perioperative anaphylaxis.
Tests
Skin tests or in vitro tests for IgE are helpful, but history is key, and challenges provide the most definitive answers.
Tryptase
Tryptase is occasionally helpful, often it is not elevated though, or can be artificially elevated in ESRD (CKD). Tryptase level peaks 1-2 hours after anaphylaxis, and should be checked within 6 hours. Tryptase is less likely to be elevated in food allergy anaphylaxis compared to other sources of anaphylaxis.
PAF
Dr. Oppenheimer reviewed the Vadas data on PAF and PAF acetylhydrolase and its association with anaphylaxis severity. PAF levels increase in anaphylaxis. There is an inverse relationship of severity of anaphylaxis and level of enzyme that breaks down PAF.
Don't forget to emphasize the importance of a Medic Alert bracelet to patients at risk of anaphylaxis.
Where to inject epinephrine (EAI)?
A reminder that IM epinephrine in the thigh leads to faster plasma levels of epineprine than IM or SQ in the arm (deltoid). Recommendation for IM injection of epinephrine in the thigh is based on serum levels in healthy controls. No efficacy studies, ethics prevent them.
Which EAI is better - EpiPen or Auvi-Q?
Needle length on an EpiPen is 1.43 cm. In a pediatric study 12% of 0.15mg and 30% of 0.3mg eligible patients would in theory not reach muscle due to obesity or other reasons.
A study involved injecting cadaver pigs with EpiPens loaded with blue dye - epineprine landed 2.5 cm into the animal despite needle length of 1.4 cm. In this animal study, material was injected about 2x the needle length due to pressure on skin and force of injection. Anaphylaxis needs more research. Does propelled epinephrine in Auvi-Q equal the same delivery when we apply Epi-Pen with a forceful swing action?
Patient comfort with the use of an epi autoinjector (EAI) increases with increased practicing in the allergists office.
Seeing an allergist = higher chance of EAI prescription for those who need it
From a survey: Only 40% of patients with a serious anaphylactic reaction had epinephrine with them per allergists’ report. Allergists think 85% of primary care doctors know little to nothing about anaphylaxis.
Good news - Allergists overwhelming prescribe epinephrine autinjectors (EAI) and instruct patients in the appropriate use of these devices. There is an overwhelming agreement among allergists (97%) that epinephrine is the first line choice of treatment for anaphylaxis.
A study of one million anaphylaxis episodes over the course of 11 years in one center showed increasing CS use and declining epinephrine use. Comparing 1993 to 2004 ER data, use of steroids INCREASING and epinephrine use DECREASING. This is an opposite of should occur.
There is no evidence that antihistamines or steroids have an effect on biphasic or “rebound” anaphylaxis. Antihistamines are considered supportive therapy for anaphylaxis and do not replace epinephrine.
A study by Rudders et al. (AAAAI 2013) of 993 patients admitted with venom induced anaphylaxis showed that only 60% were given an epineprine autoinjector (EAI) on discharge.
Use of epinephrine in emergent setting is higher when source is a stinging insect, or when patient has seen an allergist.
What can the Allergist do? Review the use of epinephrine autoinjector at each visit and Ask to see it! (make sure they have it).
Survey data of ACAAI members suggest that more than half do not conduct anaphylaxis practice drills. Interesting - only 34% of Allergists surveyed state that their staff are trained in BCLS, ACLS or PALS.
Does an action plan make a difference?
Written anaphylaxis action plans were used by 75% of responding allergists. Allergists who generate and update anaphylaxis action plans also increase patient comfort with the use of an autoinjector.
Of patients that required ER visit or hospitalization for anaphylaxis, over 60% did not have a written anaphylaxis plan.
Dr Fineman: patients with risk for anaphylaxis need a written action plans. Just teaching IM epinephrine isn't enough.
However, usefulness of anaphylaxis action plans was questioned by some responders to survey. Valid questions with no data to answer it. Data on asthma action plans is mixed, not clear that they improve outcomes. Would like to see similar studies for anaphylaxis action plans.
Who will develop a biphasic reaction in anaphylaxis?
Biphasic anaphylaxis occurs in up to 20% of anaphylactic reactions. No clear predictors for occurrence. Delay in epinephrine use is a risk factor.
2’s mnemonic:
20% of patients will develop
2nd reaction
20 minutes later
2 EAI’s prescription is always needed
There is no consistently reliable predictors for biphasic anaphylactic reactions but the initial severity and delayed epinephrine use are likely important.
Of note, biphasic reactions typically are less severe, though rare fatalities have occurred.
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