Croup is an encompassing term for illnesses affecting the larynx, trachea, and bronchi. It is a common upper respiratory illness in children characterized by inspiratory stridor, barking cough, and hoarseness. Laryngotracheitis, laryngotracheobronchitis, laryngotracheobronchopneumonitis, and spasmodic croup are all categorized in the croup spectrum. Typically, croup is differentiated into two distinct types: viral croup and spasmodic croup. A review of emergency department visits in the United States between 2007 to 2014 estimated there were approximately 400,000 croup-related visits annually (Hanna, 2019). About 3% of children are affected by croup annually, and the age range is typically between six months and three years (Sizar & Carr, 2022). Croup is characterized by swelling of the larynx, trachea, and large bronchi due to infiltration of white blood cells—the inflammation results in narrowing of the airway and partial obstruction, causing increased work of breathing and stridor.
Image 3: Croup
Children with croup typically present with one to two days of upper respiratory infection, followed by a signature seal-like barking cough, stridor, hoarseness, and difficulty breathing. Symptoms are often worse at night and may be accompanied by fever. The duration of illness is usually three to seven days, with the most severe presentation on day three or four (Sizar & Carr, 2022).
Clinicians need to observe for rapid progression of symptoms or for signs of lower airway involvement, which may suggest a more severe illness that requires rapid intervention.
A viral infection usually causes croup in the fall or early winter. Like bronchiolitis, common viral pathogens of croup include (Johnson, 2014):
- Parainfluenza or influenza
- Human coronaviruses
The Parainfluenza viruses account for more than 75% of croup diagnoses (Johnson, 2014). Parainfluenza virus type 1 is the most common cause, especially in the fall and winter months (Woods, 2022). Parainfluenza virus type 2 usually presents with milder disease than type 1, while Parainfluenza virus type 3 cases are often more severe than those of type 1 or 2 (Woods, 2022). Pediatric patients with SARS-CoV-2, particularly during the 2022 Omicron surge, have increasingly manifested with croup (Murata et al., 2022).
Bacterial infection is rarely the cause of pediatric croup illnesses. Mycoplasma pneumonia can present as a mild croup-like illness. Bacterial infections may occur secondarily to croup, and pathogens commonly include (Sizar & Carr, 2022):
- Corynebacterium diphtheria
- Staphylococcus aureus
- Streptococcus pneumoniae
- Hemophilus influenzae
- Moraxella catarrhalis
Evaluation and diagnosis of suspected croup in children should focus on identifying those with severe or rapidly professing upper airway obstruction. Healthcare workers must foster an environment that is comfortable and calming to minimize fear and anxiety, which can exacerbate subglottic narrowing, leading to the progression of the illness. Diagnosis is primarily made on clinical assessment through observation of symptoms like:
- Barking cough
- Inspiratory stridor
- History of recent upper respiratory infection symptoms like runny nose or cough
It is not recommended to pursue diagnostic testing, such as respiratory lab panels or x-ray, to diagnose croup. If an etiologic diagnosis is necessary to make decisions or inform regarding isolation and prevention practices, secretions from the nasopharynx may be obtained for viral etiology.
When symptoms are progressing rapidly or patients are not responding to routine croup treatment, ruling out other obstructive conditions is essential. Assessment findings may indicate another condition. Findings that might indicate something else is going on include (Bhatia, 2018):
- Expiratory wheezes
- Toxic appearance
- Prolonged stridor
- Loss of voice
Other obstructive conditions that might explain these findings may include (Bhatia, 2018):
- Foreign body airway obstruction
- Subglottic stenosis
- Congenital airway anomalies
- Allergic reaction/angioedema
- Peritonsillar or retropharyngeal abscess
- Bacterial tracheitis
Treatment of croup is associated with the severity of illness, primarily determined by the presence or absence of stridor at rest, work of breathing with chest wall retractions, air entry, presence or absence of pallor or cyanosis, and mental status (Woods, 2022). Most pediatric patients with croup can be managed as outpatients, but those who present with moderate to severe symptoms may require the emergency department or inpatient care.
Caregivers of children with mild croup should be instructed to treat them symptomatically with humidity, antipyretics, and hydration. Although no systematic research exists, exposure to cold night air may reduce symptoms. Mild croup may also be treated with a single dose of oral dexamethasone or prednisolone (Woods, 2021).
Furthermore, caregivers should be educated on signs and symptoms to observe for worsening conditions requiring medical attention. These symptoms include:
- Stridor at rest
- Difficulty breathing
- Pallor or cyanosis
- Severe coughing
- Drooling or difficulty swallowing
- Fatigue or lethargy
- Persistent or worsening fever
- Increased work of breathing with retractions
- Symptoms that persist for more than seven days
For those patients with moderate to severe croup, treatment in an emergency department or acute care setting includes corticosteroids (dexamethasone is preferred) and nebulized epinephrine directed towards decreasing airway edema (Woods, 2021). Supportive care includes humidified air, oxygen supplementation to maintain saturation > 90%, antipyretics, and nutrition and hydration support. Patients who respond to initial treatment should be observed for four hours and may continue supportive home treatment if they have no stridor at rest, normal oxygenation and good air exchange, no cyanosis, can tolerate fluids orally, and caregivers are instructed and understand signs and symptoms of worsening and when to seek medical attention.
The child may need to be admitted for further management under the following conditions:
- Symptoms persist
- No response to repeat epinephrine dosing
- Worsening croup symptoms
- Altered consciousness
- Impending respiratory failure
- Toxic appearance
- Need for supplemental oxygenation
- Age of less than six months old
- Concern regarding caregiver competency and/or resources
Because croup is most commonly a viral illness, antibiotics are indicated only when a primary or secondary bacterial infection is suspected (Sizar & Carr, 2022). For most cases of pediatric croup, the prognosis is excellent, and the illness resolves in a few days.