How to interpret and treat croup?

What is croup?

Croup, also known as acute laryngitis, is caused by obstruction in the upper airways due to a viral infection, such as parainfluenza virus, RSV, coronavirus, or adenovirus. Laryngitis means inflammation of the larynx, which is the voice box and includes the vocal cords.

Acute laryngitis can cause obstruction because the mucous membrane in the larynx becomes inflamed and swollen. The important anatomical point is that the airway is narrowest around the glottis/subglottis, i.e., at and just below the vocal cords. Even a small swelling here can therefore cause a significant reduction in airflow.

In children, this is particularly evident because the airway is already small. If the diameter is halved, the resistance to airflow increases.

Children aged 0.5-5 years are most susceptible to croup, but older children and adults can also get it. Swelling in the larynx often worsens when lying down, so symptoms become quite prominent when the child is trying to sleep. The clinical picture is often characterized by a "barking" cough, respiratory distress, and inspiratory stridor (a high-pitched or wheezing sound during inhalation). The reason for inspiratory stridor is that the narrowing is high up in the throat, so air is drawn in through a constricted area, creating inspiratory stridor. A hoarse voice is also typical of croup.

What do you do?

The Westley Croup Score (WCS) is a scoring system used to assess the severity of the condition:

Interpretation and treatment:

0-2 points: Often treated at home. Reassure the child. Cold air. Humidified air, such as steam, can help.
3-7 points: Moderate symptoms. Glucocorticoids. Adrenaline inhalation. Often managed at an out-of-hours clinic, but hospital admission may be considered.
8-11 points: Severe symptoms. Usually requires admission. Glucocorticoids. Adrenaline inhalation often needs to be repeated.
≥12 points: Very severe croup with risk of respiratory failure. Glucocorticoids, repeated adrenaline inhalations, and immediate admission - often to an intensive care unit. Consider respiratory support.

There are several differential diagnoses for croup:

Bronchiolitis:

Acute inflammation of the bronchioles, the lower airways. While croup/acute pharyngitis causes inspiratory stridor, bronchiolitis is characterized by expiratory stridor. Expiratory stridor occurs because the narrowing is deep in the small airways. This means that during exhalation, the airways constrict further, and air is slowly pushed out with a wheezing/prolonged expiration. Bronchiolitis often affects the youngest children, i.e., younger than 1 year, and is most often caused by RSV.

Epiglottitis:

Acute inflammation of the epiglottis, the flap of cartilage that covers the entrance to the windpipe. Swelling here can quickly narrow the upper airway and cause inspiratory stridor, difficulty swallowing, and impaired general condition. Drooling but rarely fever. This is a potential airway crisis. Epiglottitis is often caused by Haemophilus influenzae type B (Hib). Fortunately, the Hib vaccine, which is included in the childhood immunization program, has made the disease rare.

Retropharyngeal abscess:

Is a deep throat infection with a collection of pus behind the pharynx. It usually occurs as a complication of an upper respiratory tract infection, for example, a throat infection or tonsillitis. Retropharyngeal abscess is a differential diagnosis for croup because it can cause inspiratory stridor and upper airway obstruction. Suspicion is strengthened by fever, an affected child, difficulty swallowing/drooling, neck pain, or torticollis. These are findings that do not fit with uncomplicated croup. Note: Do not confuse with peritonsillar abscess (very similar terms), which is a complication of tonsillitis where the tonsils are affected. Peritonsillar abscess is characterized by unilateral tonsil enlargement with unilateral throat pain, deviation of the uvula away from the affected side, trismus, painful gaping, and fever.