Last updated on:November 5th, 2020
Croup is a viral infection of the respiratory tract that generally occurs in children between the ages of 6 months to 5 years. Parainfluenza types 1 and 3 are the most commonly implicated pathogens. Influenza A and B, adenovirus, respiratory syncytial virus, and metapneumovirus are other key agents.
Patients with croup often have a characteristic cough that is reminiscent of a seal barking; this cough appears abruptly and is more common in severe disease. Note that this finding may be absent in older children or adults, however. The underlying cause appears to be inflammation of the trachea and other subglottic structures.
Patients may manifest high-pitched wheezing sounds. This is due to turbulent airflow through partially obstructed airways.
A prodromed of nonspecific syptoms such as cough, rhinorrhea, coryza, and fever often precedes the barking cough and stridor by 24 to 72 hours.
Croup classically produces high-pitched stridor during inspiration. Expiratory stridor can occur in severe cases. Occasionally, this can be appreciated without a stethoscope. Note that there is no correlation between the degree of stridor and severity of the disease.
Signs of respiratory distress
Croup may lead to progressive respiratory distress. Mild symptoms may include a subtle barking cough, limited stridor at rest, and substernal and intercostal retractions. In moderate to severe disease these symptoms are augmented; the child may also become agitated.
Signs of respiratory failure
Signs suggestive of progression from respiratory distress into respiratory failure include lessening or cessation of the barking cough, stridor, and substernal and intercostal retractions;
and the child becoming lethargic. A dusky skin color or frank cyanosis may also be present.
Bacterial tracheitis can also present with stridor, fever, and respiratory distress; it is difficult to distinguish clinically from croup, but should be considered if the child appears particularly ill; and especially if they do not respond to nebulized epinephrine.
Gram-stains and bacterial cultures of a tracheal aspirate will confirm the diagnosis.
Epiglottitis presents with fever, stridor, and breathing difficulties. However, the presentation is more abrupt and a barking cough is not present.
Furthermore, these children tend to drool and adopt a "sniffing" position in which they lean forward with their heads tilted up in an attempt to breathe more easily.
Retropharyngeal absecesses can present with fever, stridor, and respiratory distress. However, drooling, neck stiffness or pain, dysphagia, and torticollis may also be present, while barking cough is absent.
Ingestion of a foreign body can manifest as stridor and acute breathing difficulties. However, there is no prodrome or fever, unless secondary bacterial infection occurs as well.
Acute allergic reaction
Patients with anaphylaxis, acute angioedema, and other acute allergic reactions may present with acute dyspnea and stridor. However, other signs of allergy are often present, including urticaria and swelling of the lips, tongue, and face; while barking cough is absent.
X-rays of the neck may show narrowing of the subglottic space; this is known as the steeple sign. However, this radiologic sign is of low sensitivity and is not specific for croup.
Importantly, this procedure can further agitate the patient and worsen airway obstruction. It should be used sparingly and only where bacterial tracheitis or epiglotitis have been ruled out.
Viral cultures and rapid antigen testing are not required for the diagnosis or management. Rarely, they may be considered in patients with highly atypical presentations.
Laryngoscopy is rarely performed, both due to the need for general anesthesia and because instrumentation can further irritate the airways. It is mainly indicated if other anomalies are suspected. If performed, this permits direct visualization of the laryngx, and allows for the diagnosis of tracheitis and the collection of samples for culture.
Bronchoscopy can be considered in patients with recurrent croup, as this may be secondary to an underlying anatomic anomaly.
Patients without stridor or other signs of respiratory distress can be discharged after initial treatment and observation for several hours.
When deciding about outpatient care, factors such as the distance of the closest medical center to the child's home and availability of private transport must be taken into consideration. The parents should be educated about the signs of respiratory failure that merit a return visit.
Keep child comfortable
The child should be made as comfortable as possible, as symptoms tend to worsen if they are frightened or agitated. This includes allowing the child to remain with its parents and avoiding unecessary procedures.
Antipyretics can be administered to control the fever and reduce discomfort.
Humidified air administered via mist tents has been shown to be ineffective, increase patient anxiety, and even disperse fungus. It should be avoided.
Corticosteroids should be administered to all children with with croup, regardless of severity; this has been shown to both reduce the duration of hospitalization and minimize the need for intubation and ventillation. The beneficial effects may take several hours to appear.
Nebulized epinephrine is recommended in moderate to severe croup. The onset of relief is rapid, but effects do not persist for more than two hours.
Heliox is an mixture of oxygen and helium; it is administered in certain institutions, based on the rationale that the gas reduces airflow turbulence, thus decreasing respiratory distress. Evidence supporting its use is lacking.