Laryngotracheitis, laryngotracheobronchitis, and laryngotracheobronchopneumonitis are all included in the spectrum of croup. Croup is a common respiratory illness of the trachea, larynx, and bronchi that can lead to inspiratory stridor and barking cough. The parainfluenza virus typically causes croup, but a bacterial infection can also cause it. Croup is primarily a clinical diagnosis. Potentially life-threatening conditions such as epiglottitis or a foreign body in the airway must be ruled out first. Corticosteroids should be administered to all patients with croup and epinephrine is reserved in those with moderate to severe croup.
Etiology is most commonly viral with some cases caused by bacteria.
Annually in the United States, croup accounts for 7% of hospitalizations in children younger than 5 years of age. Croup affects about 3% of children per year, typically between the ages of 6 months and 3 years. Parainfluenza virus accounts for more than 75% of croup infections. It is more common in boys than girls with a 1.5:1 ratio. Approximately 85% of cases are defined as mild croup, and less than 1% are considered severe croup.
Croup causes swelling of the larynx, trachea, and large bronchi due to infiltration of white blood cells. Swelling results in partial airway obstruction which, when significant, results in dramatically increased work of breathing, and the characteristic turbulent, noisy airflow known as stridor.
Croup is characterized by a "seal-like barking" cough, stridor, hoarseness, and difficulty breathing which typically becomes worse at night. Agitation worsens the stridor, and it can be heard at rest. Other symptoms include fever and dyspnea, but the absence of fever should not reduce suspicion for croup. Respiratory rate and heart rate may also be increased with a normal respiratory rate being between 20 to 30 breaths per minute. Visual inspection of nasal flaring, retraction, and rarely cyanosis increases suspicion for croup.
The most commonly used system for classifying the severity of croup is the Westley Score ranging from 0 to 17 points divided by five factors: stridor, retractions, cyanosis, level of consciousness, and air entry.
Westley score less than or equal to 2 indicates mild croup.
Westley score between 3 to 5 indicates moderate croup.
Westley score between 6 to 11 indicates severe croup and a score greater than 12 indicates impending respiratory failure.
More than 85% of children present with mild disease; severe croup is rare (less than 1%).
Croup is typically a clinical diagnosis based on signs and symptoms.
Treatment depends on the severity based on the Westley croup score. Children with mild croup defined as Westley croup score less than 2 are given a single dose dexamethasone. Children with moderate to severe croup defined as a Westley croup score greater than 3 are given nebulized epinephrine in addition to dexamethasone. Patients with diminished oxygen saturation should receive supplemental oxygen. Moderate to severe cases require up to 4 hours of observation and if the symptoms do not improve admission is required.
Differential diagnosis includes bacterial tracheitis, epiglottitis, foreign body aspiration, hemangioma, peritonsillar abscess, neoplasm, retropharyngeal abscess, and smoke inhalation. It is extremely important to distinguish croup with epiglottitis because of the rapid deterioration in patients with epiglottitis. A cough is highly sensitive and specific for croup, whereas drooling is highly sensitive and specific for epiglottis. Other symptoms to watch for in children with epiglottitis include acute onset dysphagia, odynophagia, high fever, and muffled voice. Children with peritonsillar abscess can have a sore throat, fever, and the classic "hot potato" voice. Children with retropharyngeal abscess can also have a fever, drooling, dysphagia, odynophagia but also have neck pain with a bulging posterior pharyngeal wall on neck radiography.
Croup is a self-limited disease with most cases resolving within a few days. Uncommon complications may include bacterial tracheitis, pneumonia, pulmonary edema, and rarely, death.
Immunization against influenza and diphtheria may reduce the incidence of croup.
A community based randomized trial of children with mild to moderate croup found no difference in symptom scores between three daily doses of prednisolone 2 mg/kg and a single dose of dexamethasone 0.6 mg/kg.