00:01
Now let's talk about the
respiratory disorder, croup.
00:04
What is croup?
Croup is a symptom
characterized by infection
and inflammation of the upper airway,
which is the trachea and larynx.
00:13
Here, on the left, you'll
see the normal larynx.
00:15
There's a normal tracheal opening and
the vocal chords are not swollen.
00:20
Over on the right, you'll
see an inflamed larynx.
00:22
In the setting of croup, the vocal chords
and the surrounding structures
cause a narrowing of the trachea,
and this causes the symptoms
we see in croup.
00:31
Some children are more prone than
others to develop croup symptoms
when they get a viral upper
respiratory infection,
and most outgrow croup by the age of
5 when their airway becomes bigger.
00:43
Croup is more prevalent in the
autumn, winter, and spring,
and typically lasts about 1 week.
00:50
The most common cause of croup are viruses.
00:53
The parainfluenza viruses types 1 and 3
are responsible for about 80% of cases.
00:59
Influenza A and B can also cause croup,
along with the respiratory
syncytial virus, or RSV.
01:06
The adenovirus and rhinovirus
can also cause croup symptoms.
01:12
Rarely, croup is caused by a bacterial
infection, including <i>staph aureus</i>,
<i>strep pyogenes, strep pneumoniae,</i>
<i>haemophilus influenzae,</i> and <i>M. catarrhalis</i>.
01:25
First, the infection, which is usually
viral, will infect the laryngeal mucosa.
01:30
Then inflammation, hyperemia,
edema, and epithelial necrosis
and shedding begin due to the
irritation from the virus,
and this is going to start the
narrowing of the subglottic region.
01:42
The child will then begin
to breathe more rapidly
and deeper to compensate
for the narrowed airway.
01:47
The respiratory rate and
effort increase in this stage
as the patient tries to move the same
amount of air through a much smaller space.
01:55
Next, the patient will develop
stridor, which is turbulent air flow.
01:59
Imagine you're sitting in a cabin in the
woods and suddenly, a blizzard develops.
02:03
Near the fireplace, you'll
hear a whistling of the air
as that turbulent air flow goes down.
02:08
Well, that's the same thing that happens
in the airway, and that's stridor.
02:11
You can hear it on the other side
of the room without a stethoscope.
02:15
The patient's chest wall
will start retracting
to try to help the lungs move in more air.
02:21
Next, the patient will develop asynchronous
chest and abdominal movements,
and the overuse of these muscles
will cause the child to fatigue.
02:29
This is a very important stage to recognize
and intervene before the
child fatigues too much.
02:37
Lastly, hypoxia and hypercapnea will develop,
and this can progress to
respiratory failure and arrest.