Croup: Etiology and Pathophysiology (Pediatric Nursing)

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.