Whenever winter looms on the calendar, many parents begin to worry that if their infants get colds, they will have trouble breathing. How can we tell when a common cold has progressed to something that needs more attention?

Kathleen Bartlett, MD, a pediatric hospitalist at Duke, explains what bronchiolitis is and when to be concerned enough to see a doctor.

-- Dennis Clements MD, PhD, MPH

What is bronchiolitis?

Kathleen W. Bartlett, MDBronchiolitis is an infection of the small airways in the lungs called “bronchioles.”  The bronchioles are tiny tubes that carry air in and out of the lungs. In bronchiolitis these tubes becomes swollen, irritated, and blocked with mucous, making it difficult for the air to move smoothly in and out of the lungs.

Bronchiolitis occurs in children under two years of age. Young children have smaller airways than older children and adults, making them more susceptible to the breathing difficulties that occur with this infection.

Bronchiolitis is most commonly caused by respiratory syncytial virus (RSV), but can also be caused by a host of other common respiratory viruses. Because these viruses tend to circulate in the winter months, bronchiolitis typically occurs from November through March in North America. There is no evidence of a bacterial cause for bronchiolitis.

Bronchiolitis can be diagnosed on the basis of symptoms and physical exam findings, although nasal secretions may be tested for some of the specific viral causes. Blood tests and chest x-rays typically are not helpful in diagnosing bronchiolitis.

What are the symptoms of bronchiolitis?

Bronchiolitis usually starts out with common cold symptoms including:

• Low-grade fevers
• Congested or runny nose
• Mild cough
• Decreased appetite

After a few days symptoms may progress to include:

• Faster breathing
• Wheezing
• Worsening cough including coughing spells
• Decreased feeding

Usually children start to get better four or five days into the illness, but the cough can last up to two-to-three weeks.

When should children with bronchiolitis see a doctor?

Most children with bronchiolitis do not need medical attention, but certain children are at risk for a more complicated course. These include children with a history of prematurity or heart disease, children who are less than 6 months old, children who attend daycare or have older siblings, and children who are exposed to cigarette smoke. 

A child with any of the following symptoms should see a doctor:

• Rapid breathing
• Grunting with each breath
• Flaring of the nostrils with each breath
• Using the muscles between the ribs or at the base of the neck to breathe
• Decreased wet diapers or poor feeding

Rarely children may have pauses in their breathing or turn blue with bronchiolitis. If this happens, you should call 911 immediately.

How is bronchiolitis treated?

Because bronchiolitis is caused by viruses, there are no medications that can cure the infection. Antibiotics and steroids are not helpful in most cases of bronchiolitis.

The limited treatment available is aimed at supporting the child through the illness and relieving symptoms. It is reasonable to try an inhaled asthma medication called albuterol to see if it can relax the airways and make breathing easier.  For most children with bronchiolitis, albuterol does not help. 

Frequent suctioning of the nose with saline drops and a bulb syringe is also recommended. Since infants prefer to breathe through their noses, this simple treatment may make a child more comfortable and improve feeding tremendously.  

Children with bronchiolitis are at risk for dehydration, so parents should encourage fluid intake even if the appetite is decreased.

Although most children with bronchiolitis are managed at home, approximately 2 percent of young children in the U.S. are hospitalized with bronchiolitis each year. Reasons for admission usually include one or more of the following:

• Low oxygen saturation (amount of oxygen measured in the blood stream)
• Difficulty breathing
• Poor feeding causing dehydration
• Pauses in the breathing

Even in the hospital, care is aimed at supporting the child as her own immune system fights off the viral infection. Typically children in the hospital receive oxygen until their saturations are back to normal, intravenous fluids until their feeding improves, and monitoring until their breathing improves. Suctioning is also a mainstay of hospital care. 

In addition, hospital physicians may try nebulized hypertonic saline, a concentrated salt water solution that is given as an inhaled treatment to attempt to break up secretions in the lungs. None of these treatments cure the infection; they simply support the child through the illness. Hospitalization usually lasts one-to-three days, but in some severe cases may last for weeks.

Can bronchiolitis be prevented?

Twenty percent of infants in the U.S. are diagnosed with bronchiolitis, and many more likely have a milder, unrecognized version of the disease. However, the following may reduce a child’s chances of getting bronchiolitis:

• Good hand washing
• Avoiding exposure to other sick children or adults
• Avoiding cigarette smoke exposure
• Breastfeeding

Select children who are at very high risk of severe bronchiolitis may be given monthly injections of a medication called palivizumab (Synagis). This injection is a temporary antibody against RSV. It does not provide lasting immunity the way vaccines do. Because palivizumab is expensive and only partially effective in preventing bronchiolitis, it is reserved for premature infants and those with congenital heart disease.

-- Kathleen W. Bartlett, MD, is a pediatric hospitalist at Duke.

-- Dennis Clements, MD, PhD, is the chief of primary care pediatrics at Duke Children's Hospital.