Bronchiolitis is a common lung infection in young individuals. The viral infection involves the lower respiratory tract and can present with signs of mild to moderate respiratory distress. Bronchiolitis is a mild, self-limited infection in the majority of children but may sometimes progress to respiratory failure in infants. Bronchiolitis is managed supportively with hydration and oxygen. No specific medications treat the infection.

It is important to know that respiratory syncytial virus is just one cause of bronchiolitis. The infection can occur in individuals of any age, but overall, the most severe symptoms tend to be common in infants.

The most common virus associated with bronchiolitis is the respiratory syncytial virus. However, over the years, many other viruses have been found to cause the same infection, and they include the following:

• Human rhinovirus

• Coronavirus

• Human metapneumovirus

• Adenovirus

• Parainfluenza virus

• Human bocavirus

RSV accounts for the majority of cases, although in about 30% of infants, there may be 2 viruses present at the same time.

Risk factors include:

• Low birth weight (premature infants)

• Age less than 5 months

• Low socioeconomic population

• Airway anomalies

• Congenital immune deficiency disorders

• Parental smoking

• Crowded living environment

• Chronic lung disease (bronchopulmonary dysplasia)

Differential Diagnosis

• Asthma

• Bacterial pneumonia

• Gastroesophageal reflux disease (GERD)

• Vascular ring

• Croup

• Foreign body aspiration

• Pertussis

Prognosis

Bronchiolitis is a self-limited infectious process. It is commonly managed with supportive care, hydration, fever control, and oxygenation. When the disorder is recognized and treated, the prognosis is excellent. The majority of children recover without any adverse effects. Past studies suggest that infants with severe bronchiolitis will develop wheezing in the future, but this has not been borne out by longitudinal studies.

About 3% of infants will require admission to the hospital, and the mortality rates vary from 0.5% to 7%. The large variation in mortality is because of different risk factors and lack of availability of intensive care units in certain countries.

Complications

Complications include:

• Nosocomial infection in infants who are admitted

• Barotrauma is ventilation is required

• Arrhythmias induced by beta-agonists

• Nutritional deficiencies if there is persistent vomiting

The hallmark of management for children with bronchiolitis is symptomatic care. All infants and children who are diagnosed with bronchiolitis should be carefully assessed for adequacy of hydration, respiratory distress, and presence of hypoxia.

Children who present with mild to moderate symptoms can be treated with interventions like nasal saline, antipyretics, and a cool-mist humidifier. Those children with severe symptoms of acute respiratory distress, signs of hypoxia, and/or dehydration should be admitted and monitored. These children need aggressive hydration. The use of beta-adrenergic agonists like epinephrine or albuterol, or even steroids, has not been shown to be effective in children with bronchiolitis. Instead, these children should be provided with humidified oxygen and nebulized hypertonic saline. Ensuring that the infant is well hydrated is key, especially for those who cannot eat. Oxygen therapy to maintain saturations just above 90% is adequate.

Children who develop signs of severe respiratory distress may progress to respiratory failure. These children may require intensive care for mechanical ventilation or non-invasive support. A high-flow nasal cannula is an emerging modality of non-invasive support for children with bronchiolitis. Clinical trials are in progress.

Passive immunization against RSV is available with palivizumab for those who are at the greatest risk for severe illness. During the RSV season, this requires monthly injections of the drug, but this may not only be expensive but not also not practical for most infants.

Current recommendations by the American Academy of Pediatrics support the use of palivizumab during the first year of life for children with a gestational age less than 29 weeks, symptomatic congenital heart disease, chronic lung disease of prematurity, neuromuscular disorders that make it difficult to clear the airways, airway abnormalities, and immunodeficiency. Prophylaxis may be continued in the second year of life for children who require continued interventions for chronic lung disease of prematurity or those who remain immunosuppressed.

RSV can be dangerous for infants and young children. Each year in the United States, an estimated 58,000-80,000 children younger than 5 years are hospitalized due to RSV infection. Children at greatest risk for severe illness from RSV include the following:

• Premature infants
• Infants up to 12 months, especially those 6 months and younger
• Children younger than 2 years with chronic lung disease or congenital (present from birth) heart disease
• Children with weakened immune systems
• Children who have neuromuscular disorders, including those who have difficulty swallowing or clearing mucus secretions

Products to Protect Children from RSV

Two monoclonal antibody products – nirsevimab (Beyfortus) and palivizumab (Synagis) – can help protect babies and young children from severe disease from an RSV infection. Monoclonal antibodies are not vaccines. They provide an extra layer of defense that helps fight RSV infections and protect children from getting very sick. The protection these antibodies provide wanes over time. These products are not treatments for a child who already has RSV infection.

Nirsevimab is recommended for all infants younger than 8 months who are born during – or entering – their first RSV season (typically fall through spring). One dose of nirsevimab can protect infants for 5 months, the length of an average RSV season. A dose of nirsevimab is also recommended for some children between the ages of 8 and 19 months who are at increased risk of severe RSV and who are entering their second RSV season.

Palivizumab is limited to children under 24 months of age with certain conditions that place them at high risk for severe RSV disease. It must be given once a month during RSV season.

If you have any questions about monoclonal antibody products to prevent RSV disease, talk to your child’s doctor. Scientists are gathering and reviewing data on a vaccine intended to be given to pregnant people to protect infants in their first RSV season. Data being reviewed focus on the safety and efficacy of the use of this vaccine in pregnant people to protect their infants.

Severe RSV

Virtually all children get an RSV infection by the time they are 2 years old. Most of the time RSV will cause a mild, cold-like illness, but it can also cause severe illness such as

• Bronchiolitis (inflammation of the small airways in the lung)
• Pneumonia (infection of the lungs)

Some children are at increased risk of severe RSV disease, including those who were born prematurely, or who have chronic lung or heart disease or a weakened immune system.

Two to three out of every 100 infants with RSV infection may need to be hospitalized. Those who are hospitalized may require oxygen, IV fluids (if they aren’t eating and drinking), and mechanical ventilation (a machine to help with breathing). Most improve with this type of supportive care and are discharged in a few days.

Symptoms of RSV

RSV may not be severe when it first starts. However, it can become more severe a few days into the illness. Early symptoms of RSV may include:

• Runny nose
• Eating or drinking less
• Cough, which may progress to wheezing or difficulty breathing

RSV in Very Young Infants

Infants who get an RSV infection almost always show symptoms. This is different from adults, who can sometimes get RSV infections and not have symptoms. In very young infants (less than 6 months old), the symptoms of RSV infection may include:

• Irritability
• Decreased activity
• Eating or drinking less
• Apnea (pauses in breathing for more than 10 seconds)

Fever may not always occur with RSV infections.

Call your healthcare provider if you or your child is having difficulty breathing, not drinking enough fluids, or experiencing worsening symptoms.

Everyday Preventive Measures Can Help Limit the Spread of RSV

RSV season typically starts in the fall and peaks in the winter in most regions of the United States. Like other respiratory viruses, you can help limit the spread of RSV by using the following preventive measures:

• Wash your hands often
  Wash your hands often with soap and water for at least 20 seconds, and help young children do the same. If soap and water are not available, use an alcohol-based hand sanitizer. Washing your hands will help protect you from germs.
• Keep your hands off your face
  Avoid touching your eyes, nose, and mouth with unwashed hands. Germs spread this way.
• Avoid close contact with sick people
  Avoid close contact, such as kissing, and sharing cups or eating utensils with people who have cold-like symptoms.
• Cover your coughs and sneezes
  Cover your mouth and nose with a tissue or your upper shirt sleeve when coughing or sneezing. Throw the tissue in the trash afterward.
• Clean and disinfect surfaces
  Clean and disinfect surfaces and objects that people frequently touch, such as toys, doorknobs, and mobile devices. When people infected with RSV touch surfaces and objects, they can leave behind germs. Also, when they cough or sneeze, droplets containing germs can land on surfaces and objects.
• Stay home when you are sick
  If possible, stay home from work, school, and public areas when you are sick. This will help protect others from catching your illness.