When we approach a patient with anaphylaxis we always wanna be thinking about the ABCs
so we wanna make sure that again, we are monitoring them very carefully
or placing them on a cardiac monitor to keep tabs on their heart rate and rhythm,
continuous pulse ox to look at their respiratory status,
frequent blood pressure checks in case they are 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 want to get back up from an anesthesiologist, an otolaryngologist,
or somebody else who is expert in difficult airways 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 patient’s 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 1 to 1000 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 in a book when a patient is anaphylaxing.
You wanna know the correct dose and concentration of epi,
so we give it through the intramuscular route, at the 1 to 1000 concentration and the adult dose is 0.3 to 0.5 mg.
The pediatric dose is 0.01 mgs per kilograms so you can calculate that based on the child’s actual
or estimated body weight but for an adult, very straight forward, 0.3 to 0.5.
This can be repeated every five to ten 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, I'm gonna say it one more time.
It’s 1 to 1000 epinephrine that we use.
This is not the same as cardiac arrest epinephrine which is 1 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 1 to 1000 epi,
0.3 to 0.5 mgs 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 vasodilation 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 delay hypersensitivity reactions
down the road and then for patients who are on beta blockers
you want to 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 discharge with anaphylaxis
so if they're asymptomatic at 48 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 sub-group 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 I'm epinephrine should definitely be observed in the hospital.
Again, requiring multiple doses of epinephrine indicates a more severe reaction upfront
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 on-going 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 bee sting allergy or peanut allergy,
they all should be send 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 stand point
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.