In this lecture we’re going to talk about pediatric asthma
and how we should approach a wheezing child.
So, we see this all the time,
a child who is six years old, who comes in to see you, who has wheezing on exam,
an expiratory, high-pitched noise.
This child may be in moderate respiratory distress,
he might have a runny nose or congestion or a cough.
So what is your medical diagnosis?
How do you make that medical diagnosis?
Let’s drill down on asthma.
So before we even get started though,
I want to talk a little bit about the difference between stridor and wheezing.
There’s a simple trick to be able to help you make a differential diagnosis
on a patient who has wheezing versus a patient who has stridor
and I want to make that very clear,
Here is a child with lungs,
an airway,
and two main stem bronchi.
If we were to imagine that this child had accidentally swallowed a ball
and the ball had landed up in the throat area
but it had not entered the cavity of the chest,
we might imagine that when this child breathed in
there was a negative pressure created below this ball
and that airway space would tighten.
As a result, while breathing in, this child would make a noise, a sort of --
noise, which is from the narrowing of the airway against the ball while breathing in.
But, while breathing out,
you can imagine that this air would blow past the ball,
enlarging that area around the ball,
and allowing for a silent exhalation.
Patients with stridor typically have noise on inhalation
for this very reason but not so much in exhalation.
This would be a classic noise for example in croup,
which is a viral inflammation of the upper airway.
Now, of course patients can’t have inspiratory and expiratory wheezing,
but this is classically how we think about stridor.
Wheezing, on the other hand,
let’s now imagine this ball was a little bit smaller
and made it all the way down to the right main stem bronchus,
or in this case the left main stem bronchus, it doesn’t really matter.
The point being though that now, when this child is breathing in,
the airway is expanding and this is because the entire lung is expanding
so the space in that airway is actually getting bigger
and typically, the patient will not have any noise while breathing.
However, when breathing out,
that airway is now collapsed down and you can see that now the
airway will be pressing up against the ball
and the child will have an exhalational noise.
So wheezing is typically on exhalation more than it is on inhalation.
Now, in a patient with asthma, you can absolutely get inhalational
and exhalational wheezing as a result of generally very narrowed airways,
but will typically see the exhalational wheeze first.
So if you see a patient with wheeze, what could be causing it?
There’s a lot more than asthma that causes wheeze
and it’s important to know the difference,
especially if the patient has never wheezed before.
In the infancy period, zero to one years,
patients may very likely have bronchiolitis.
Bronchiolitis is a viral inflammation of the lung,
it does not cause smooth muscle constriction typically,
and it’s mucus balls or it’s very small amounts of mucus collecting in these airways
which cause a narrowed space and absolutely present with wheezing.
If a patient is wheezing they may very well have bronchiolitis and not asthma,
especially if they have upper respiratory infection symptoms like congestion.
Bronchopulmonary dysplasia can present with wheeze,
a foreign body can absolutely present with wheeze usually that’s in one location,
aspiration in general if a child has oral motor dysfunction
and has a hard time swallowing,
some of that liquid might have gotten down to their lungs,
or anatomic abnormalities of the airway can also cause wheeze.
For instance, a CCAM or a congenital cystic adenomatous malformation
may be pressing on that airway.
In the age one to four,
we often see virally induced wheeze, again, bronchiolitis.
This may be a case of early asthma;
this again might be a foreign body, especially if it’s rapidly onset,
mom found the child was normal one minute and then next minute was wheezing;
and this might be the age at which a child is presenting
with the pulmonary symptoms of cystic fibrosis.
Over five years of age, it’s probably asthma.
Patients can totally have vocal cord dysfunction,
which might cause both stridor and wheeze.
Patients may have a hypersensitivity pneumonitis,
or patients may get something more complex
like allergic bronchopulmonary aspergillosis,
which is an allergic hyperresponsiveness to Aspergillus in the environment.
So if you see a patient with wheezing, what are the key questions to ask?
Well, the first is at what age did wheezing begin?
If this is the first wheeze, we’re going to manage it a little bit differently
than if this child has been wheezing for a long time.
Knowing the age of wheeze starting will help you with the differential diagnosis.
You should ask whether this wheezing is episodic or persistent.
Was it sudden onset, which might be a foreign body,
or gradual onset, which might be asthma?
Is it associated with triggers?
Every time the child is in his dusty grandmother’s house
he starts wheezing, that’s a strong indicator of asthma.
Or has it responded to albuterol in the past?
If a child has a history of wheezing which is responsive to albuterol,
this is probably asthma.
So when you’re getting at asthma as a diagnosis,
it’s very important to get a sense of how severely ill is the patient
because in asthma the key is control and prevention.
So you’ll want to ask whether they have many events per week
or less than one every two weeks.
You will want to ask about night time awakenings.
Frequently, these children will awaken with cough
and that’s a good sign of asthma out of control.
It’s important to ask about whether this asthma interferes with normal activity.
Can the child do sports like the other kids?
If the child does have asthma,
it’s incredibly important to know how often they’re getting systemic steroids.
Systemic steroids, as we’ll talk about in a bit,
have a lot of side effects and we want to avoid those.
Does the child have a history of previous hospitalizations
or does the patient have previous visits to an intensive care unit?
These are all signs of asthma out of control.
One key historical fact is, was this child premature.
Premature infants have a much higher risk for asthma than non-premature infants
and that can tip you off as to what’s going on.