When we approach a patient with anaphylaxis, we always wanna be thinking about the ABC’s.
So we wanna make sure that again, we are monitoring them very carefully,
we’re placing them on a cardiac monitor to keep tabs on their heartrate and rhythm,
continuous pulse oximetry to look at their respiratory status,
frequent blood pressure checks in case they’re developing hypotension.
Every patient should get supplemental oxygen to keep their sat above 90%.
Every single patient needs vascular access which is gonna enable you to treat them
should you need to with fluids or any other necessary medications.
You always wanna be ready to manage the airway in these patients
and it’s really, really important to emphasize that patients with anaphylaxis
will often be difficult airways.
Because, if they do have airway involvement, it’s gonna include swelling.
So the normal airway anatomy is gonna be distorted,
there might be edema of the larynx itself.
It might be difficult to visualize and/or difficult to pass an endotracheal tube.
So if you’re an emergency physician,
again, hopefully, you have the technical skills to manage this airway situation.
But if you’re managing anaphylaxis on a hospital floor or in a clinic setting,
you clearly would wanna get back up from an anesthesiologist, an otolaryngologist,
or somebody else who is expert in difficult airway management techniques.
The real mantra with anaphylaxis is hope for the best but prepare for the worst.
So you wanna be ready for this patient to really decompensate on you.
The vast majority of patients don’t,
and the clinical course of anaphylaxis with appropriate treatment is usually pretty benign.
But for that small percent of patients who do go on to occlude their airways
or have vascular collapse requiring aggressive resuscitation,
you wanna be ready to deal with that.
You wanna have the necessary equipment, the necessary IV access, and the monitoring,
so that you’ll be able to identify early if the patient is decompensating.
As far as your medical management goes, epinephrine is absolutely the correct answer.
It is the mainstay of management
and if there’s only one drug that you’re gonna give to a patient with anaphylaxis,
it should be epi.
Epi is given intramuscularly at a one to 1.000 concentration.
Okay? Again, you don’t have to memorize a whole heck of a lot of drug doses called
but this is one that you really need to know.
You don’t wanna be fishing around in your phone
or looking at a book when a patient is anaphylaxing.
You wanna know the correct dose and concentration of epi.
So we give it through the intramuscular root at the one to 1.000 concentration
and the adult dose is 0.3 to 0.5 milligrams.
The pediatric dose is 0.010 mg/kg.
So you can calculate that based on the child’s actual or estimated body weight.
But for an adult, very straightforward, 0.3 to 0.5.
This can be repeated every 5 to 10 minutes as needed
but if you’re having to give multiple repeat doses of epinephrine,
you probably wanna think about starting an IV epinephrine infusion
so that you can more satisfactorily manage your patient over a longer period of time.
So epinephrine has a number of physiologic effects.
It’s a vasoconstrictor, it’s a bronchodilator,
and it also directly decreases mast cell degranulation.
So it reverses some of the damage that the mast cells have already done
by clamping down on the vasculature
and decreasing the vasodilation that you see as part of anaphylaxis.
It also relaxes the airways and improves the pulmonary status
but in addition to reversing the pathophysiology that’s already there,
it’s gonna prevent things from getting worse
by decreasing the likelihood of future mast cells
releasing their inflammatory mediators and adding additional fuel to the fire.
I mentioned the epinephrine dose and I’m gonna say it one more time.
It’s one to 1.000 epinephrine that we use.
This is not the same as cardiac arrest epinephrine which is one to 10.000.
So the dose is different and the concentration is different.
Don’t mix these things up.
You need to know your two different formulations of epi
and you need to know when to give each one.
Anaphylaxis is one to 1.000 epi 0.3 to 0.5 mg for an adult given intramuscularly.
In addition to epinephrine, there are other adjuncts that you can use.
Fluid resuscitation is often used especially for patients who have hypotension
or any form of cardiovascular collapse.
You might need several liters of fluid for these patients
but honestly, if your patient is significantly hypotensive,
odds are the problem is more one of vasoconstriction
rather than one of hypovolemia,
so you really wanna make sure that you’re using epinephrine
and not relying on fluids to reverse hypotension among patients with anaphylaxis.
We also use antihistamines.
You can use both H1 and H2 blockers.
Diphenhydramine is classically given which is an H1 blocker
but you can also use Ranitidine or other H2 blockers
which do work synergistically to help further decrease the effects of histamine
that’s already been released.
Corticosteroids are beneficial not so much in the acute phase
because they take a really long time to begin working
but they can help prevent delayed hypersensitivity reactions down the road,
and then for patients who are on beta blockers,
you wanna think about the possibility of giving them glucagon
and that’s largely because you wanna reverse the effects of the beta blockers
so that you can get maximum impact from your adrenergic agonist.
So patients who are already beta-blocked,
you won’t be able to give them the benefit of epinephrine
because those beta receptors are already pharmacologically blocked.
So you use glucagon to reverse the beta-blocker
and then, they become more receptive to the epinephrine
which is gonna help their respiratory status.
As far as disposition goes,
actually, most patients can be safely discharged with anaphylaxis.
So if they’re asymptomatic 4 to 8 hours after their initial presentation,
it’s probably safe to send them home.
Most delayed hypersensitivity reactions are gonna occur within 8 hours.
So you don’t really need to observe patients much longer than that.
However, there are a subgroup of patients who won’t get better and do require admission
and those include patients who have airway involvement or hypotension.
If they’re showing you life threatening manifestations of anaphylaxis,
you probably wanna air on the side of a longer observation period.
You probably wanna watch them through
and beyond that delayed hypersensitivity window
and make sure that they are really fully stable before you let them go home.
Patients who require more than two doses of IM epinephrine
should definitely be observed in the hospital.
Again, requiring multiple doses of epinephrine indicates a more severe reaction up front
and you wouldn’t wanna miss a life threatening delayed hypersensitivity reaction in this group.
And then lastly, patients who don’t really have great outpatient support
or they don’t have good follow-up,
you might think about bringing them into the hospital more
to help link them to care and ensure that they get the follow-up
that they need for allergy testing and ongoing treatment.
One thing that’s really important for all of our patients with anaphylaxis
is to identify the trigger if you can
and help the patient take steps to avoid exposure to that trigger
and if they do have exposure to that trigger,
make sure that they have the necessary tools to treat at home.
So patients who have a bee sting allergy or peanut allergy,
they should all be sent home with epinephrine auto injectors
that they can use to self-administer epinephrine
if they do sustain another exposure
and they should all be educated about the importance of avoiding these triggers.
So take home points, anaphylaxis is a common disease process.
It’s benign in most cases but it can be deadly.
Common triggers include foods, stings, and drugs.
Although, in a lot of cases, you’ll never identify what the trigger was.
We diagnose anaphylaxis in patients who have respiratory or circulatory compromise
in the setting of allergic exposure.
We wanna always be prepared for the worst from an airway standpoint
and be ready to manage a difficult airway in anaphylactic patients.
We also wanna be prepared for vascular collapse with good IV access,
volume resuscitation and of course, epinephrine.
Every patient with anaphylaxis should be treated with epi
and not to do so is not to give that patient adequate treatment for their underlying disease process.
Thank you very much.