Croup

Croup is an acute viral inflammation of the upper and lower respiratory tracts.

• Croup is an infection of the upper airways, especially the larynx.
• It is usually caused by viruses; in rare cases bacteria cause a potentially fatal illness, acute epiglottitis.
• Croup is infectious and can be spread especially in the first few days.
• Typical croupy cough sounds coarse and barking.
• A harsh, crowing sound during inspiration is associated with croup.
• Croup is treated with humidified air, fluids, corticosteroids (injected or administered orally) and adrenaline nebulisers.
• Epiglottitis is a serious illness that can present similarly to croup but can cause total airways obstruction that is rapidly fatal.
• Croup often develops in the evening or night and, if it is not severe initially, might worsen during the night. Close observation is thus important.
• Acute onset of stridor may be caused by the inhalation of a foreign body

Description

Croup is an acute viral inflammation of the upper and lower respiratory tracts, which involves the larynx (the “voice box” containing the vocal chords), trachea (windpipe), the bronchi (airways leading to the lungs), the bronchioles (airways in the lungs) and the lung tissue itself. However, the obstruction that results in the main symptoms is caused by swelling and inflammatory secretions in the area immediately around the vocal chords. This obstruction results in difficult breathing, and the increased effort required for breathing tires the ill child.

In very severe cases the lungs are unable to work efficiently and move oxygen into the blood with the result that the child becomes hypoxic.

Croup is characterised by inspiratory stridor (a harsh, crowing sound when inhaling), subglottic swelling (swelling below the vocal chords) and respiratory distress that is most pronounced on inspiration.

Acute epiglottitis is a condition that should always be thought of in cases of croup. Here a bacterial infection (Haemophilus influenza type B) causes acute swelling of the epiglottis which can rapidly lead to airway obstruction. If the diagnosis is not made promptly, the child is likely to die.

Cause

Croup is mostly caused by viruses. Most commonly the parainfluenza viruses (especially type 1) are involved, but the respiratory syncytial virus (RSV), influenza A and B, adeno-, rhino- and measles viruses can also cause croup. Mycoplasma pneumoniae has been identified as a bacterium that causes croup.

Croup caused by influenza can be particularly severe and can also occur outside the age bracket of six months to three years. In winter and spring, RSV and influenza viruses tend to dominate, but in autumn the parainfluenza virus is found more often.

The disease can be spread by droplet infection.

Symptoms

Croup is usually preceded by two or three days of an upper respiratory tract infection (like a cold or influenza). Characteristically, a barking, often spasmodic, cough and hoarseness develop as the inspiratory stridor starts. Gagging and vomiting may occur with the coughing. Low-grade fever is common, but often fever of 38°C to 40°C is associated with the onset of croup. This often occurs in the middle of the night. The child wakes up with breathing difficulties and rapid breathing, using all chest muscles. As it becomes more severe and the child tires, he or she may become blue (cyanosed) due to the lack of oxygen.

Prevalence

Viral croup occurs mainly in children between 3 months and 5 years of age, affecting boys more often than girls. Seasonal outbreaks are common. In the winter, when it is colder, croup is found more often, but it can occur at any time of the year.

Course

Most croup patients can be cared for at home but one needs to be alert to deterioration of the condition. If acute symptoms develop, the child should be treated at an emergency department. In most cases, medication will settle the inflammation well in a few hours and the child's immune system will fight the virus infection. The illness then lasts about three days, but a cough can continue for another two weeks. It can sometimes recur after a short period or every year, but as the child grows and the diameter of the airways increases, the inflammation affects the airways less and less. Thus children eventually outgrow the tendency to get croup.

Risk factors

• Age between three months and five years
• Colder months of the year
• Exposure to other children with croup (in crèches)
• Male gender

When to see a doctor

A doctor should be consulted promptly when a child develops any of the signs of croup, especially when a barking cough sets in and stridor (a rough, raspy, high-pitched sound) develops when the child breathes in.

It is an emergency requiring immediate medical attention if:

• Breathing difficulties are severe
• The skin, fingernails or lips turn blue or grey
• Abnormally fast shallow breathing develops (more than 60 breaths a minute)
• The child can't seem to get enough air
• The croup symptoms don't improve after 20 minutes of inhaling either steamy bathroom air or cool outdoor air
• Has stridor on both expiration as well as inspiration

Some bacterial infections (epiglottitis) can have similar symptoms to those of croup. The stridor is soft, with snoring or gurgling exhalations. Cough is not very prominent. In very rare cases, when the airways become totally blocked, such infections can be rapidly fatal.

The child should be taken to an emergency department immediately if he or she:

• Is very hot
• Appears very sick
• Drools saliva, being unable to swallow
• Needs to lean forward with the mouth open to breathe

When visiting the doctor, parents should take along all medication used over the previous few days. It is important to know the names and doses.

Diagnosis

The history can provide valuable information that can make a diagnosis quite obvious. The urgency of the situation can also be ascertained.

In early stages or if the child is not severely affected, there may just be a croupy barking cough that may signal croup.

In more severe cases, there will be obvious breathing problems and often a harsh stridor on inspiration. Listening to the chest with a stethoscope will reveal long inspiration times and stridor over the larynx. When lung collapse has occurred, the breathing sounds may be diminished. A chest X-ray may show lung collapse. In 50% of children there is fever.

Acute epiglottitis needs to be excluded if the condition seems severe. An X-ray of the soft tissues of the neck may show a markedly swollen epiglottis.

The possibility of an inhaled foreign body must always be remembered.

Treatment

General

Admission to hospital is likely to be necessary if there are breathing difficulties and stridor is present both on inspiration as well as expiration. If the child becomes ill in the evening, it is likely to worsen later on, so that admission is generally a good idea.

Croup can be frightening for affected children, the parents and the health workers. Children need to be comforted and reassured. Often the symptoms settle down as soon as children stop to struggle, but this may be difficult especially when they reach a hospital. Close monitoring is important during the early stages of croup as breathing difficulties can develop rapidly.

Minimal handling helps to settle children down. They should be nursed in a warm, humid environment, and not be sedated with any drugs. Taking fluids should be encouraged, but forcing fluids should not be necessary. In the first few days activity should be kept to a minimum.

Croup is infectious during the first few days and others in the household may be infected. However, infection usually only causes a sore throat or cough in older individuals. When the temperature is normal and the patient feels better, he or she can go back to day-care centres.

In epiglottitis the airway can become blocked within six hours from onset of the disease. The ill child should not lie down, as this may obstruct the airway, and must be taken to an emergency department immediately. Here the airway may need to be secured by intubation, but since this may fail, invariably leading to complete obstruction, someone needs to be present to create a surgical airway if needed. Antibiotics should be administered intravenously and the patient admitted to a paediatric intensive care unit under the care of a paediatrician.

Home

If the symptoms are mild and the child is not distressed, the illness can be managed at home. However, children must be observed carefully overnight, as symptoms may worsen in the middle of the night when there is no one around. When children with croup wake up during the night with difficulty breathing and clearing the airways, it is important to calm them to prevent a vicious cycle of cough and further irritation. Children can be distracted by reading with them or rocking them. Keep them quiet if possible.

Moisture in the air can make it easier for the ill children to breathe – use a cool humidifier or vaporiser. Although steam has not been proven to lessen symptoms, it soothes the airways. Whenever it makes the patient more distressed, however, it should be stopped immediately. Distress worsens the condition more than the treatment helps. Always be careful not to scald the patient. A bath may help by creating sufficient humidity in the bathroom.

In young infants, blocked noses can make breathing more difficult. Noses can be cleaned gently with careful instillation of salt-water nose drops (1/4 teaspoon of table salt in one cup of water) into the nasal openings every few hours, followed by gentle suction from an ear bulb syringe. Initially paracetamol or ibuprofen syrup may help, especially to control fever. Aspirin should not be given in children with viral illnesses, as it may cause Reye syndrome.

If the child still does not improve, taking him or her into cool night air may help. Children often improve in the car on the way to the hospital. If the symptoms improve, sleeping with the child for the rest of the night is important. If there are any doubts, see a doctor – delay may be fatal.

Medication

Antibiotics have no place in management of croup, unless epiglottitis is suspected.

The initial treatment is the inhalation of nebulised adrenaline through a face mask. This may be required frequently as the effect of the adrenaline wears off.

A single injection of the corticosteroid dexamethasone is often considered in severe croup. The stress leading up to the injection is usually considerably less than trying inhalation masks. However, if the child tolerates inhalation without distress, this may be useful.

Oral corticosteroid syrup or tablets (prednisone) may be beneficial for the next few days to settle the inflammation, and should be taken as soon as possible, as the onset of action is delayed by several hours.

Antibiotics are essential for epiglottitis. Ceftriaxone or chloramphenicol must be given intravenously. Rifampicin should be used to treat those involved with the patient as prophylaxis to prevent spread of the infection to others.

Surgery

Surgery is only of relevance in epiglottitis when an artificial airway needs to be created following a failed intubation. This is an emergency procedure and is followed by insertion of a tube connected to a mechanical ventilator.

(Reviewed by Dr John D. Burgess, Red Cross Children's Hospital)