What is Croup (Viral laryngotracheobronchitis)

Croup is a syndrome, which is a collection of symptoms and signs that consists of hoarse voice, harsh barking cough and an inspiratory stridor (a high pitched noice made with inspiration). There are many causes of croup, the most common of which is viral laryngotracheobronchitis. Many other conditions can cause croup, some of these other causes include:

  • Supraglottic obstruction (obstruction of the airways occurring above the epiglottis)
    • Acute enlargement of the tonsils
    • Foreign body in the airways
    • Retropharyngeal abscess (abscess behind the tissues of the pharynx)
    • Epiglottitis (rare)
    • Acute angioedema
  • Laryngeal/ subglottic (obstruction occurring below the epiglottis)
    • Viral croup
    • Spasmodic croup
    • Foreign body
    • Bacterial tracheitis (inflammation of the trachea)
    • Laryngomalacia +/- viral infection (in infants)
    • Diptheria
    • Thermal/ chemical injury
    • Intubation trauma
    • Laryngospasm (spasm of the larynx)
  • Tracheal
    • Foreign body
    • Bacterial tracheitis
    • Tumour (e.g. anterior mediastinal lymphoma)
    • Trauma (e.g. haematoma)
    • Congenital abnormality

Statistics on Croup (Viral laryngotracheobronchitis)

2% of children develop croup annually and it is a common cause of airway obstruction. Children aged from 6 to 36 months are most commonly affected, with most of those children being between 1 and 2 years of age.

Risk Factors for Croup (Viral laryngotracheobronchitis)

Risk factors for developing croup include the following:

  • Seasonal variation; with the highest incidence in late autumn, however the condition can occur all year round.
  • Viral infection; 75% of all cases are the result of infection with parainfluenza virus, most commonly type I. Other causes include respiratory syncytial virus (RSV), metapneumovirus, influenza A and B, adenovirus, and mycoplasma.
  • Prematurity
  • Young age
  • Asthma, specifically for spasmodic croup

Progression of Croup (Viral laryngotracheobronchitis)

Croup usually begins as a condition that mimics the common cold. In the first 1 to 3 days of the condition patients suffer from a combination of runny nose, sore throat, slight cough as well as a low grade fever. After the initial phase, symptoms that are characteristic of an upper airway obstruction occur, these include the characteristic barking cough, hoarseness as well as an inspiratory stridor. The symptoms of croup can worsen at night, and usually resolve after a week. It is important to note that agitated children can develop life threatening aggravation of symptoms, which is why it is important to keep the child as calm and as happy as possible. As a rule of thumb, older children suffer less severe symptoms than younger children.

Symptoms of Croup (Viral laryngotracheobronchitis)

Children with croup initially present with symptoms of the common cold which include:

  • Runny nose (rhinorrhoea)
  • Cough
  • Sore throat
  • Slight fever

Later on in the course of the condition they may develop symptoms of upper airway obstruction which include:

  • Barking cough
  • Hoarseness
  • Inspiratory stridor

Rarely, in severe forms of the disease, features of respiratory distress can occur:

  • Soft tissue recession (indrawing of the skin due to increased effort of breathing)
  • Irritability
  • Lethargy
  • Cyanosis (blue discolouration of the skin due to poor oxygenation of blood)

Because of the increased effort of breathing children may become dehydrated, this may be seen as:

  • Sunken eyes
  • Dry mucous membranes such as dry mouth, dry eyes (i.e. the child will cry with less tears)
  • Reduced urine output
  • Reduced skin turgor i.e. the skin loses its elasticity

Clinical Examination of Croup (Viral laryngotracheobronchitis)

When a child sees a doctor with a suspected episode of croup, an examination of the child will be performed. The doctor will make his best efforts not to agitate the child during the examination as this can cause aggravation of the child’s symptoms. Things that the doctor is likely to perform when your child is seen may include:

  • Checking the child’s respiratory rate, heart rate and oxygen saturations
  • Looking to see if the child is lethargic, irritable, interacting as they usually would
  • Checking the child for signs of dehydration
  • Doing a complete respiratory examination which includes: looking at the child’s chest to look for evidence of increased effort of breathing, feeling the child’s trachea to see if it has moved, listening to the chest.
  • Other examinations may be performed at the discretion of the doctor depending on the child’s presentation.

How is Croup (Viral laryngotracheobronchitis) Diagnosed?

In most situations the doctor will not perform any investigations on a child with croup. This is to avoid causing unnecessary distress to the child, especially in those children who are already in a lot of distress. In children who have a confusing set of symptoms that do not fit the typical picture for croup an x-ray of the neck may be taken.

Prognosis of Croup (Viral laryngotracheobronchitis)

Croup generally resolves after 48 hours of onset of symptoms, however it can last up to a week. In general 5% of children with croup are hospitalized, this rate of hospitalization is increased in children who develop complications of the disease.

How is Croup (Viral laryngotracheobronchitis) Treated?

General Care

  • It is imperative to ensure that the child is comfortable and as unagitated as possible, this can be done by avoiding stressful procedures and examinations.
  • The doctor may sit the child on the primary care givers lap in order to reduce their distress.
  • Oxygen is usually given to children with croup since it is believed to improve outcome.


  • Analgesics and antipyretics e.g. paracetamol, this is to reduce the child’s distress due to pain or fever
  • Adrenaline is useful in children with severe croup and respiratory failure. Adrenaline helps to improve the child’s symptoms immediately, but it doesn’t have any long term benefits.
  • Oral steroids are given to all children with croup, they help to reduce the severity of a child’s symptoms and the duration of illness

Croup (Viral laryngotracheobronchitis) References

  1. Behrman R.E., Kliegman R.M., Jenson H.B, Nelson Textbook of Pediatrics, 17th Ed., Saunders, 2004
  2. Bjornson CL & Johnson DW, ‘Croup-treatment update’, Pediatric Emergency Care, 2005, vol. 21, no.12, pp.863 – 873
  3. Cherry JD, ‘State of the evidence for standard of care treatments for croup: are we where we need to be?’,2005, Pediatric Infectious Diseases, vol. 24, no. 11, pp. 198 – 202
  4. Fitzgerald DA & Kilham HA, ‘Croup: assessment and evidence based management’, MJA, 2003, vol 179, pp. 372 -377
  5. Johnson D ‘Croup’, Clinical Evidence, 2006, vol. 15, pp.1-3
  6. Moore M & Little P, ‘Humidified air inhalation for treating croup (review)’, Cochrane Database of Systematic Reviews, 2006, Issue 3, Art. No CD002870. DOI: 10.1002/14651858.CD002870.pub2.
  7. Stannard W & O’Callaghan C, ‘Management of Croup’,2002, Paediatric Drugs, vol. 4, no. 4, pp. 231 – 240

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