How do we truly diagnose asthma?
On your exam they may mention spirometry
with post bronchodilator response.
Typically, they’ll give something
like a methacholine challenge
and look to see if they can
A response of around 20% is
indicative that this patient
is reacting to the
The reality is that we don’t
typically use this test,
it’s probably not
The vast majority of children, we simply use
a history of responsiveness to albuterol
and other stigmata, like eczema,
to make the diagnosis of asthma.
Rapid viral testing
is not helpful.
Viruses can be a trigger for asthma.
Viruses can happen in patients
with bronchiolitis, too
And the sad issue is, is that if you look at
healthy children walking down the street,
one in four will test
positive for a virus.
So, viral testing has a low positive
and a low negative predictive value.
Consider allergy testing or
pulmonary function testing
really only in children who
are over five years of age,
who you’re having a hard time controlling
or you’re really not certain of
what the diagnosis might be.
For a child with a previous
diagnosis of asthma,
who is coming with an
we are not going to typically
get labs or x-rays.
We simply treat the patient.
For hospitalized children
with no history of wheezing,
a chest x-ray is usually done.
This is because, again, while
we’re going to start off
presuming this child
may have asthma,
it’s also possible the child has another
problem which you haven’t figured out yet.
An example would be a foreign
body or another condition,
maybe a pulmonary lymph node
that’s compressing the airway.
This is the kind of thing where they
can look very similar at first,
and then over time you
notice they really aren’t
responding to the albuterol
like you might expect.
A chest x-ray can sometimes be helpful in
distinguishing between these problems.
So, back to asthma.
We have a patient who is coming
in with an acuter exacerbation.
They’re wheezing, they’re
right there in your office.
What are you going to do?
Well, for the acute exacerbation,
the mainstay is albuterol.
Albuterol is a powerful beta-agonist.
It’s going to cause bronchodilation and
allow those airways to really open up.
Patients should feel
relief relatively quickly.
There is an available levoalbuterol
or racemic albuterol.
It’s more expensive, but not more
effective, so most people don’t use it.
Sometimes we use it because it
may have less cardiotoxicity
to children with underlying
But for the vast majority of patients
with asthma, it’s not necessary.
Additionally, during an acute exacerbation
we are going to give systemic steroids.
This can be oral or it can be
IV or it can be intramuscular.
Neither route is better than another,
they all take about two hours to kick in.
If you recall,
it’s a complicated pathway that steroids
take to actually reduce inflammation.
The steroid has to make it
into the nucleus of the cell,
which then changes via
the production of both
prostaglandins and leukotrienes.
There’s this back filled pathway
that if you apply a steroid
it takes about two hours
before you’re going
to really notice those
steroids kicking in,
but they will kick in in two hours, so
get them started as soon as you can.
The other important thing in an acute
exacerbation, it is a learning moment.
So perhaps not while
they’re acutely ill,
but after they’ve started to get better,
it’s a good time to
counsel about triggers
because prevention is what
asthma care is all about.
So in the acute setting you may see
more than just albuterol used.
If the albuterol really isn’t turning
the child around the corner,
they may use continuous albuterol
through a nebulized machine,
but there are other medications
that can help as well.
An example would be magnesium.
Magnesium is a 2+ ion just like calcium
and, thus, is a competitive inhibitor
in the sarcoplasmic reticulum
of the smooth muscle
cell inside the airway.
So the magnesium is going to
allow that airway to relax.
Side effect though is that it really
relaxes all your smooth muscle,
and so, you may
Terbutaline is sort of like IV
albuterol, it’s intravenous.
But in children with
albuterol, it’s given IV
and it’ll cause more of that
smooth muscle dilatation
and usually a
Children on terbutaline are usually
watched in the ICU setting.
When they’re in the ICU setting you’ll
note that we like to avoid intubation.
If a patient is in respiratory distress
from, say, a trauma or a bad pneumonia,
we usually will go get around to
intubating them pretty quickly.
In asthma, we’re going to
generally drag our heels on that
and the reason is, remember, asthma is
a problem with getting the air out.
If I now intubate the child, I’m
going to be pushing more air in,
and I’m worried about a pneumothorax,
where that lung may actually pop
and air may escape into the side of
my chest wall causing a pneumothorax.
That’s not very good.
There are some other agents that can help.
Ketamine is a bronchodilator
and some of the
inhalational agents like
halothane or bronchodilators.
There are many different agents
we can use in the ICU setting
to help dilate those
So in a hospitalized child
who is not in the ICU,
how are we going to
manage these children?
Well, generally, we’re going to start
off with continuous albuterol.
In some places, they do that on the wards,
in some places, that’s
in the ICU setting only.
And generally, you’re going
to have a continuous
nebulizer of albuterol
at very high doses.
Then, when the patient
is feeling better,
they’ll generally transition
to every two hours or Q2.
We’ll watch them, we’ll use asthma
scores to see how they’re doing,
and once they’ve been
stable for a few treatments
we’ll switch them to Q4
or every four hours.
At that time, they’re almost
ready to be discharged,
and in most settings we’ll wait
for two Q4 hour treatments,
and if they’re still looking
good they’re okay to go home.
We typically discharge them if they
do not have an oxygen requirement,
if they do not need albuterol more than
every four hours for at least two episodes,
and if they don’t have