Today at noon
rounds we discussed anaphylaxis. Anaphylaxis is a serious allergic reaction
that is rapid in onset and may cause death. Here are some clinical pearls on
anaphylaxis.
1.
Have
anaphylaxis on your differential diagnosis for an acutely sick patient. If you
don’t think about it you may miss it!
2.
Anaphylaxis
can mimic other conditions and present differently, which is why it is
important to think about it (Internal thought bubble: “Could this acutely sick
patient have anaphylaxis?”)
Signs/symptoms of anaphylaxis
can include:
-
Symptoms/signs
occur rapidly (minutes to hours) after exposure to a known or likely allergen
-
Skin and mucosal symptoms and signs (ie. hives, pruritus, flushing, swollen
lips, swollen tongue, angioedema) *This is an important clue to look for as it
is present in up to 90% of anaphylactic episodes
-
Respiratory compromise (i.e. nasal congestion, laryngeal itching
and “tightness” in the throat, hoarseness, stridor, dyspnea, wheeze,
bronchospasm, hypoxemia)
-
Cardiovascular compromise (could also present with hypotension syncope,
incontinence, dizziness, tachycardia)
-
Gastrointestinal
(i.e. crampy abdominal pain, nausea, vomiting, diarrhea)
Priorities for the
management of anaphylaxis:
1.
ABCs (airway, breathing, circulation) CALL FOR
HELP!
o
Airway: early
intubation is often indicated and one needs to be alert for signs of airway
compromise. Call for help from an airway expert (respiratory therapy and
anesthesia) early!
o
Breathing: Supplemental oxygen
o
Circulation: IV fluids (normal saline bolus)
o
IV
access (two large bore IV catheters) and monitors (cardiac monitors, continuous
oxygen saturation monitoring and frequent blood pressure monitoring)
2.
Epinephrine
o
Prompt recognition of anaphylaxis and administration
of epinephrine is key!
o
Studies
have shown failure or delay in administration of epinephrine may increase the
risk of death1
o
The
first choice is Epinephrine IM
(intramuscular) 1:1000 concentration (1 mg/mL): give epinephrine 0.3-0.5 mg intramuscularly in mid-outer thigh, maximum
3 doses
o
If
intramuscular epinephrine is not available quickly, give epinephrine IV. Epinephrine IV (intravascular) 1:10,000 concentration (0.1
mg/mL): give epinephrine 0.1 mg IV slowly over 1-3 minutes. Note that the concentration of epinephrine
that is given intravascularly and is often on code carts is different than the
concentration of epinephrine that is given intramuscularly. This can cause
dosing errors and cardiovascular complications due to overdosing. The 10mL
prefilled syringes of epinephrine used in cardiac arrest on the code carts are
1mg of epinephrine in a 10mL prefilled syringe. Therefore, to give 0.1mg for
anaphylaxis, you only give 1/10th (1mL) of the prefilled syringe
that is given in the ACLS algorithms! Usually a response is observed after a single
dose, giving you time to prepare an epinephrine infusion. If there is an
inadequate response to the first dose, a second dose can be given.
o
If
there is an inadequate response to initial IM or IV epinephrine, you can start
a continuous epinephrine infusion, beginning with epinephrine IV infusion 0.1 mcg/kg/minute
o
If on a
beta-blocker and no response to epinephrine, you can give glucagon 1-5mg IV
over 5 minutes then an infusion at 5-15 mcg/min
3.
Removal of inciting antigen (i.e. stop
infusion of a suspect medication)
4.
Adjuncts:
o
Glucocorticoids:
Methylprednisolone (Solumedrol) 125 mg IV
o
Ventolin
PRN
o
Anti-histamines:
i.
Diphenhydramine
(Benadryl) 50 mg IV
ii.
Ranitidine
50 mg IV
1.
Dhami S
et al. Management of anaphylaxis: a systematic review. Allergy.
2014;69(2):168-75.
