Anaphylaxis is a rapid-onset life-threatening
allergic reaction.
Because of its high risk of mortality, it
is a diagnosis that you cannot afford to miss.
Think of this condition in a patient who presents
with an urticarial rash and one other system
affected – a rule I like to call “Skin
+ 1”.
Anaphylaxis is most commonly caused by one
of the following three triggers:
Foods such nuts, shellfish, and eggs and milk
especially in kids;
Medications including antibiotics like penicillin
and sulfa drugs, aspirin, and IV contrast
used in diagnostic imaging procedure; and
Environmental: things like insect stings from
bees and wasps, and latex.
Prior exposure to one of these triggers sensitizes
individuals to release massive amounts of
histamine, leukotrienes and other inflammatory
mediators from mast cells in their blood leading
to a spectrum of symptoms.
If only the skin is involved, it is not anaphylaxis,
but called urticaria, as anaphylaxis requires
2 organ systems to be involved.
Urticaria presents with an intensely itchy
hive like rash on the trunk, limbs, and face.
This is not a life threatening condition and
can be treated with antihistamines, such as
Benadryl, for a few days.
On the other hand, if the skin plus one other
system or “Skin + 1” is involved then,
the criteria for anaphylaxis has been met,
and this is a medical emergency that you just
cannot afford to miss.
The other systems (or the “+1”) that are
commonly involved include:
Respiratory: and can present with upper airway
involvement with stridor, tongue, lip, or
neck swelling or lower airway presenting with
wheezes, cough and shortness of breath.
Airway obstruction is the number one cause
of death from anaphylaxis.
Cardiovascular: presenting with hypotension
or frank shock and complete circulatory collapse.
Gastrointestinal: presenting with nausea,
vomiting, diarrhea, and abdominal cramps due
to the massive histamine release.
The treatment of anaphylaxis must be started
as soon as the condition is suspected.
Time is of the essence.
The most important drug to administer is EPINEPHRINE.
This is what will save lives.
Do not hesitate to give it.
It starts working within seconds of being
given.
The dose is epinephrine 0.3mg-0.5mg in a 1/1000
concentration IM, usually given in the thigh.
The pediatric dose is 0.01mg/kg.
Epinephrine can be repeated every 5 minutes
if necessary.
Prompt recognition, early intervention, and
preventing further episodes with allergy testing,
allergy avoidance, and the Epi-Pen use are
all key for managing this life threatening
condition.
