CROUP

Croup (laryngotracheobronchitis) is a respiratory disease which afflicts infants and young children, typically aged between 3 months and 3 years. The respiratory symptoms are caused by inflammation of the larynx and upper airway, with resultant narrowing of the airway.

Signs and symptoms

Croup is characterized by a harsh 'barking' cough, stridor (a high-pitched sound heard on inhalation) and fever. Hoarseness is usually present. More severe cases will have respiratory distress.

The 'barking' cough (often described as a "seal like bark")[1] of croup is diagnostic. Stridor will be provoked or worsened by agitation or crying. If stridor is also heard when the child is calm, critical narrowing of the airway may be imminent.

In diagnosing croup, it is important for the physician to consider and exclude other causes of shortness of breath and stridor, such as foreign body aspiration and epiglottitis.

On a frontal X-ray of the C-spine, the steeple sign suggests the diagnosis of croup.

Causes

Croup is most often caused by parainfluenza virus, primarily types 1 and 3, but other viral and possibly bacterial infections can also cause it. It is most common in the autumn but can occur year-round, with a slight predilection for males.

The respiratory distress is caused by the inflammatory response to the infection, rather than the by infection itself. It usually occurs in young children as their airways are smaller and differently shaped than adults', making them more susceptible. There is some element of genetic predisposition as children in some families are more susceptible than others.

An entity known as spasmodic croup also occurs, due to laryngeal spasms.

Treatment

The treatment of croup depends on the severity of symptoms.

One of the simplest ways to treat or help with croup is to inhale cool mist. This was the sole treatment for croup throughout the nineteenth and most of the twentieth century. Hospitals today use a "blowby" apparatus for this purpose, but taking the child outside in moist night air may achieve the same result. Alternatively, steam from hot water or a humidifier will have a similar effect. These simple techniques may help in some cases, but they may not be enough to completely get rid of the symptoms, and there is very little hard evidence to support their efficacy.

Mild croup with no stridor, or stridor only on agitation, and just a cough may simply be observed, or a dose of inhaled, oral, or injected steroids may be given. When steroids are given, dexamethasone is often used, due to its prolonged physiologic effects.

Moderate to severe croup may require nebulized adrenaline in addition to steroids. Oxygen may be needed if hypoxia develops. Children with moderate or severe croup are typically hospitalized for observation, usually for less than a day. Intubation is rarely needed (less than 1% of hospitalized patients).

Steam from running, hot bath water may help the croup.

Prognosis

Viral croup is a self-limited disease, but can very rarely result in death from complete airway obstruction. Symptoms may last up to 7 days, but typically peak around the second day of illness. Rarely, croup can be complicated by (or confused with) an acute bacterial tracheitis, which is more dangerous.