What is bronchiolitis?


Bronchiolitis is an infection of the lower respiratory tract that usually affects infants. There is swelling in the smaller airways or bronchioles of the lung, which causes obstruction of air in the smaller airways.

What causes bronchiolitis?

The most common cause of bronchiolitis is a virus, most frequently the respiratory syncytial virus (RSV). However, many other viruses have been involved, including:

  • Parainfluenza virus

  • Adenovirus

  • Influenza

  • Human metapneumovirus

It is rarely caused by bacteria, usually mycoplasma pneumoniae.

Initially, the virus causes an infection in the upper respiratory tract, and then spreads downward into the lower tract. The virus causes inflammation and even death of the cells inside the respiratory tract. This leads to obstruction of airflow in and out of the child's lungs.

Facts about bronchiolitis

  • Bronchiolitis usually occurs in the winter and early spring.

  • The most common age group affected by bronchiolitis is 3 to 6 months of age, but occurs in children up to 24 months.

  • The following risk factors increase the likelihood that a child will develop bronchiolitis:

    • Having older children in the home

    • Day care attendance

    • An infant that is not breastfed

    • Exposure to smoke

What are the symptoms of bronchiolitis?

The following are the most common symptoms of bronchiolitis. However, each child may experience symptoms differently. Symptoms may include:

  • Common cold symptoms, including:

    • Runny nose

    • Congestion

    • Fever

    • Harsh cough that often becomes more severe as the condition progresses

  • Changes in breathing patterns (the child may breathe fast or hard; you may hear wheezing, or a high-pitched sound)

  • Decreased appetite (infants may not eat well)

  • Fussiness

  • Vomiting, especially after coughing

The symptoms of bronchiolitis may resemble other conditions or medical problems. Always consult your child's doctor for a diagnosis.

How is bronchiolitis diagnosed?

Bronchiolitis is usually diagnosed solely on the history and physical examination of the child. Many tests may be ordered to rule out other diseases, such as pneumonia or asthma. In addition, the following tests may be ordered to help confirm the diagnosis:

  • Chest X-rays. A diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.

  • Pulse oximetry. An oximeter is a small machine that measures the amount of oxygen in the blood. To obtain this measurement, a small sensor (like a Band-Aid) is taped onto a finger or toe. When the machine is on, a small red light can be seen in the sensor. The sensor is painless and the red light does not get hot.

  • Nasopharyngeal swab. This is done for respiratory syncytial virus (RSV) and other respiratory viruses. These tests yield rapid results for presence of RSV or other viruses. This is needed for babies who require admission so that their care team can practice the appropriate infection precautions.

Treatment for bronchiolitis

The treatment for bronchiolitis is typically supportive care and observation based on:

  • Your child's age, overall health, and medical history

  • Severity of the disease

  • Expectations for the course of the disease

  • Your opinion or preference

Most cases are mild and can be treated at home. Antibiotics are ineffective in the treatment of bronchiolitis. Some infants, if they are having severe breathing problems, may be treated in the hospital. While in the hospital, treatment may include:

  • Intravenous (IV) fluids if your child is unable to drink well

  • Oxygen therapy and a ventilator may be needed

  • Frequent suctioning of your child's nose and mouth (to help get rid of thick secretions)

If your child's doctor feels your child is stable enough to be treated at home, the following treatment may be recommended:

  • Encourage fluid intake

  • Frequent suctioning (with a bulb syringe) of your child's nose and mouth (to help get rid of thick secretions)

  • Always consult your child's doctor for advice before giving over-the-counter (OTC) cold and cough medicines to children younger than 6 years of age.

  • Acetaminophen (Children's or Infants' Tylenol) for fever, as ordered by your child's doctor. Do not give a child aspirin, because this medication has been linked to Reye syndrome, a disease of the brain and liver.

Prevention of bronchiolitis

The best way to prevent bronchiolitis is consistant hand-washing. An injection may be given to help decrease the chances of getting respiratory syncytial virus (RSV). The medication is called palivizumab (Synagis) and recommended only for high-risk infants, including premature infants (age at birth less than 35 weeks) and infants with chronic lung disease during RSV season. Specific recommendations regarding who should receive this immunoglobin are made by the American Academy of Pediatrics and can be discussed with your child's doctor.


Reviewed by Jane M. Lavelle, MD

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