Definition

Croup syndrome is an infection of the upper respiratory tract, causing airway obstruction with a cough that sounds like a barking seal. It presents symptoms caused by swelling around the vocal cords (larynx), windpipe (trachea), and bronchi.

Causes

Croup syndrome is caused by viruses, typically parainfluenza viruses. These viruses can be transmitted through droplets or fluid particles released from the respiratory tract during coughing or sneezing. The virus in these droplets can also survive for some time on toys and other surfaces. If a child touches a surface exposed to the virus and then touches their eyes, nose, or mouth, they can become infected.

In addition to parainfluenza viruses, croup syndrome can also be caused by:

• Influenza A and B viruses
• Measles virus
• Adenovirus
• Respiratory syncytial virus (RSV)

Croup syndrome caused by bacteria typically begins with a viral infection that worsens due to uncontrolled bacterial growth in the respiratory tract. Common bacteria associated with bacterial croup include:

• Corynebacterium diphtheriae
• Staphylococcus aureus
• Streptococcus pneumoniae
• Haemophilus influenzae
• Moraxella catarrhalis

Risk factor

Croup syndrome most commonly occurs in children aged 6 months to 3 years. Children have narrower airways than adults, making complaints related to croup syndrome more common in children. Croup syndrome occurs more frequently in boys than in girls. While croup syndrome can be found in teenagers or adults, such cases are very rare.

Symptoms

Usually, croup syndrome starts with nonspecific respiratory symptoms such as a runny nose, sore throat, and cough. Fever may also occur, but typically the fever temperature is not very high (around 38-39 degrees Celsius). Then, within 1-2 days, typical croup syndrome symptoms usually appear, such as:

• Hoarse voice
• Cough with a barking seal-like sound, exacerbated by crying, anxiety, and restlessness
• Noisy breathing or significant respiratory effort, characterized by flaring nostrils and chest retractions during breathing, and neck and rib muscles appearing to move when breathing
• Child appearing pale or blue (rare)

These symptoms are generally more severe at night and occur for about 3-5 days.

Diagnosis

Croup syndrome is usually diagnosed based on the signs and symptoms present in the child. The doctor may inquire about the child's symptom history and whether there are similar cases in other children nearby. Additionally, the doctor may perform examinations of your child's respiratory tract, both through the mouth (to check the throat) and the chest (to look for signs of abnormality in the lungs).

Other examinations are rarely routinely performed but may be done under certain conditions. For example, a chest X-ray examination may be performed if there is suspicion of other conditions such as foreign bodies in the respiratory tract and problems with the epiglottis (throat valve), both of which can cause total airway obstruction and require emergency management.

In very rare cases, a child may be referred for a laryngoscopy examination, which involves inserting a tube with a camera at the end to view the shape of the airway. Typically, this referral is only done if there is suspicion of airway abnormality in the child.

Laboratory tests are also rarely performed in these cases, except in certain conditions, such as when standard management cannot handle the symptoms. These tests may include a complete blood count or diphtheria examination because Corynebacterium diphtheriae can cause croup syndrome. Blood gas analysis may be performed if the child appears to experience decreased respiratory effort due to fatigue. Tests related to fluid adequacy in children are also necessary if the child refuses to eat and drink due to croup syndrome.

Management

The management of croup syndrome depends on its severity. If croup symptoms are mild, the child will receive corticosteroid medications to relieve swelling in the larynx, trachea, and bronchi. If symptoms are moderate, the doctor may administer medications through inhalation (nebulization). If the child appears to be struggling to breathe or experiencing decreased oxygen saturation (oxygen sufficiency in the blood), supplemental oxygen may be given.

In cases of severe symptoms, the child may initially be treated in the emergency department and then hospitalized if symptoms do not improve. In the emergency department, the child will receive inhaled drug therapy to expedite the entry of the drug into the airways. In severe cases, the child may require intubation through the mouth, although this is relatively rare.

Medication to reduce cough symptoms is usually not given. Antibiotics are also typically not given because croup syndrome is most likely caused by a virus. However, if symptoms do not improve or a bacterial infection exacerbates croup symptoms, antibiotics will be administered. Therefore, antibiotics should only be used as prescribed by a doctor.

Complications

Generally, croup syndrome is mild, so it does not cause complications. However, a small number of children may experience respiratory disturbances that require emergency management. Emergency management may involve the insertion of a breathing tube in severe cases. Hospitalization is also rarely performed because croup syndrome is typically mild. The recovery rate is high without leaving residual symptoms.

Prevention

Prevention of croup syndrome is similar to preventing the common cold, flu, and COVID-19. Prevention can be done as follows:

• Washing hands with soap or hand sanitizer.
• Keeping children away from others who are sick or unwell.
• Teaching children to cough or sneeze into their inner elbow to prevent the spread of disease to others.
• Completing childhood vaccinations related to croup syndrome, namely diphtheria and Haemophilus influenzae type B. There is currently no vaccine for parainfluenza viruses.

According to the 2020 Indonesian Pediatric Society (IDAI) immunization schedule, diphtheria and Haemophilus influenzae type B vaccinations are typically given at ages 2, 3, and 4 months, along with tetanus, pertussis (whooping cough), polio, and hepatitis B vaccinations. Then, the first diphtheria vaccination booster is given at 18 months of age, the second at 5-7 years of age (can be done during the School-Age Children Immunization Month in grade 1 elementary school), and the third booster at 10-18 years of age (can be done during the School-Age Children Immunization Month in grade 5 elementary school).

When to see a doctor?

If your child's symptoms are severe, worsen, last for more than 5 days, or do not improve with medications, you should bring your child back to the doctor. Immediately visit the nearest doctor if your child experiences the following:

• Breathing with a high-pitched, noisy sound when inhaling and exhaling.
• Breathing accompanied by a high-pitched sound when not crying or anxious.
• Excessive drooling or difficulty swallowing.
• Appearing anxious, restless, tired, or confused.
• Breathing at a faster rate than usual.
• Difficulty breathing, panting.
• Changes in skin color to bluish-grey near the nose, lips, and nails (cyanosis).