Croup by Lucy Rubin and Dr. Alexander Hirsch.
Learning objectives.
By the end of this video, the viewer
will understand the basic pathophysiology,
clinical presentation, diagnosis,
and management of croup.
Introduction.
Croup is a common acute upper respiratory illness
seen in infants and children, affecting about 5%
of children in their second year of life.
Most commonly, it is seen between the ages of 6 and 36
months, although it can affect children older
and younger than this as well.
It has a peak incidence in the fall and early winter,
and is generally considered a mild, self-limited illness,
but can be complicated by respiratory distress
and upper airway obstruction.
Pathophysiology.
Croup affects the upper airway, and is also
referred to as laryngotracheitis,
or an inflammation of the larynx and trachea.
It is most commonly due to parainfluenza virus,
which affects the nasal pharynx before spreading distally.
Other viral etiologies include respiratory syncytial virus,
adenovirus, enterovirus, human bocavirus, and influenza.
The inflammation causes narrowing of the larynx
just below the vocal cords, called the subglottic airway.
The cartilage in this part of the airway
forms a complete ring, which restricts the airway's ability
to expand when inflamed.
Inflammation in this area causes the distinctive barky cough
and stridor, which are hallmarks of the disease.
Clinical presentation.
A patient with croup often but not always
presents with initial upper respiratory infection symptoms.
These initial symptoms are followed by fever,
hoarseness, a barky cough--
[CHILD COUGHING]
--and stridor, which is a high-pitched sound
heard upon inspiration, indicating some level
of upper airway obstruction.
[WHEEZING]
The symptoms characteristically can wax and wane,
often worst at night, and can become more pronounced when
a child is anxious or upset.
If there are signs of respiratory distress, hypoxia,
cyanosis, or stridor at rest, this should prompt concern
for severe airway obstruction.
Diagnosis.
The differential diagnosis for a child with stridor
aside from croup includes angioedema--
as seen in allergic reactions--
epiglottitis, retropharyngeal abscess,
foreign body aspiration, inhalation injury,
or anatomic anomalies of the airway.
Evaluation for suspected croup should
include a thorough history and physical exam
to exclude these less common etiologies of stridor.
When asking about the history, be
sure to ask about onset and progression
of the illness, recent oral intake, presence of dysphasia
or drooling, a choking episode, and any history of croup,
underlying airway abnormalities, previous intubations,
or respiratory conditions.
A recent history of a viral URI can be reassuring
when trying to make a diagnosis of croup.
When performing a physical examination,
the first step should be an overall assessment
of the child.
Are the vital signs normal?
Does the child appear comfortable,
or are they working hard to breathe?
Is the child awake or sleepy?
Do they appear dehydrated?
A thorough pulmonary exam is also necessary,
listening for any abnormal sounds
on inspiration or expiration.
In particular, listening for stridor and for a barky cough.
Many children with mild croup will
have stridor when they are upset,
which will improve once they have calmed down.
Stridor at rest is concerning for more severe disease.
Croup is a clinical diagnosis.
Chest and neck X-rays and lab work
are not routinely recommended, unless the diagnosis of croup
is uncertain.
If a neck X-ray is obtained, it may
show evidence of subglottic narrowing, known
as a steeple sign.
Management.
Appropriate management of croup depends
on the severity of the case.
Croup is graded using the Westley score, which
categorizes patients based on chest wall retraction, stridor,
cyanosis, level of consciousness, and air entry.
Mild cases without respiratory distress or stridor at rest
can be treated in the clinic with a single dose
of oral steroids, usually dexamethasone, and at home
with supportive measures, such as antipyretics
and oral hydration.
Some clinicians recommend humidity such as hot showers,
but studies have not demonstrated
the efficacy of this.
Moderate to severe cases with presence of retractions
or stridor at rest should be treated
with oral, intramuscular, or intravenous steroids,
and nebulized racemic epinephrine.
This works to decrease airway edema
by causing vasoconstriction of precapillary arterioles,
leading to decreased capillary pressure and fluid resorption.
Inpatient hospitalization should be considered
if improvement is not seen with these therapies
or if a child has required multiple doses
of racemic epinephrine.
If there is evidence of impending respiratory failure,
an ICU admission with intubation may be required.
But this is seen in less than 1% of patients
presenting with croup.
Possible complications of croup include
secondary bacterial infections and recurrent croup.
However, most cases resolve without complications
within one to three days.
In summary, croup is an upper respiratory tract infection,
often caused by parainfluenza virus,
seen in young children in the fall and early winter.
Clinical features include a barky cough and inspiratory
stridor.
Management may include supportive measures, steroids,
and nebulized epinephrine, with most cases resolving
within three days.
Thank you for watching this video on croup.