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Bronchiolitis

By

Rajeev Bhatia

, MD, Phoenix Children's Hospital

Reviewed/Revised Mar 2024
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Bronchiolitis is a viral infection that affects the lower respiratory tract of infants and young children under 24 months of age.

  • Bronchiolitis usually is caused by viruses.

  • Symptoms include runny nose, fever, cough, wheezing, and difficulty breathing.

  • The diagnosis is based on symptoms and a physical examination.

  • Treatment is primarily supporting the child through the illness with fluids and occasionally with oxygen.

  • Most children do well at home and recover in a few days, but some need to be hospitalized.

The Bronchi and Bronchioles
VIDEO

The airways resemble an upside-down tree. The trunk is the windpipe (trachea), which branches into large airways called bronchi. The bronchi themselves branch many times into smaller airways, ending in the smallest airways, which are called bronchioles. Bronchioles are as small as 1 half of a millimeter (or 2/100 of an inch) across. Their walls have a thin, circular layer of smooth muscle that can relax or contract, thus changing airway size.

Bronchiolitis typically affects children younger than 24 months of age and is most common among infants 2 to 6 months of age. Each year, 150 million children worldwide are diagnosed with bronchiolitis. Some of these children are hospitalized.

Bronchiolitis often occurs during epidemics and usually in the winter. In the northern hemisphere, most cases occur from December to February. In the southern hemisphere, most cases occur from May to July.

Causes of Bronchiolitis

Bronchiolitis is most often caused by infections with

Infection with any of these viruses can cause inflammation of the airways. The inflammation causes the airways to narrow, obstructing the flow of air into and out of the lungs. In severe cases, children have a low level of oxygen in their bloodstream.

Infection may be more common or more severe among infants whose mothers smoke cigarettes, particularly those who smoked during pregnancy.

Parents and older siblings can be infected with the same virus, but for them the virus usually causes only a mild cold.

Symptoms of Bronchiolitis

More severely affected infants breathe rapidly and shallowly, use a lot of their respiratory muscles to breathe, and have flaring of their nostrils. They seem fussy and anxious and can become dehydrated because of vomiting and difficulty with drinking. A fever usually is present but not always. More than half of children 3 to 18 months old also develop an ear infection.

Premature infants and infants younger than 2 months old sometimes have episodes where they stop breathing briefly (apnea). In very severe and unusual cases, children in these groups may develop a bluish or grayish discoloration around their mouth (cyanosis Cyanosis Cyanosis is a bluish or grayish discoloration of the skin resulting from an inadequate amount of oxygen in the blood. Cyanosis occurs when oxygen-depleted (deoxygenated) blood, which is bluish... read more ) because of a lack of oxygen.

Diagnosis of Bronchiolitis

  • A doctor's evaluation

  • Pulse oximetry

  • Sometimes mucus swab or chest x-ray

Doctors base the diagnosis of bronchiolitis on the symptoms and the physical examination. Doctors measure oxygen levels in the blood by placing a sensor on a finger (pulse oximetry Pulse oximetry Both arterial blood gas testing and pulse oximetry measure the amount of oxygen in the blood, which helps determine how well the lungs are functioning. Arterial blood gas tests are invasive... read more ).

For severe cases, doctors sometimes swab mucus from deep inside the nose to try to identify the virus in the laboratory. A chest x-ray Chest Imaging Chest imaging studies include X-rays Computed tomography (CT) CT angiography Magnetic resonance imaging (MRI) read more or other laboratory tests may be done.

Treatment of Bronchiolitis

  • At home, fluids by mouth

  • In the hospital, oxygen therapy and fluids by vein

Home treatment

Most children can be treated at home with fluids and comfort measures.

During the illness, frequent small feedings of clear fluids may be given. Increasing difficulty in breathing, bluish or grayish skin discoloration, fatigue, and dehydration indicate that the child should be hospitalized. Children who have congenital heart disease or lung disease or an impaired immune system may be hospitalized sooner and are far more likely to become quite ill from bronchiolitis.

Hospital treatment

Fluids are given by vein if the child cannot drink adequately.

Inhaled medications that open the airways (bronchodilators) may be tried. Although these medications relieve wheezing and airway narrowing caused by asthma Asthma in Children Asthma is a recurring inflammatory lung disorder in which certain stimuli (triggers) inflame the airways and cause them to temporarily narrow, resulting in difficulty breathing. Asthma triggers... read more Asthma in Children , their effectiveness in treating bronchiolitis is questionable. Corticosteroids (to suppress inflammation) may be beneficial for some children.

Doctors no longer use the antiviral medication ribavirin (given by nebulizer) except for children whose immune system is extremely weak and whose infection is severe. Antibiotics are not helpful unless the child also has a bacterial infection.

Prevention

Nirsevimab and palivizumab are two medications that contain antibodies against RSV. These medications are available in the United States to help prevent RSV Prevention Respiratory syncytial virus infection and human metapneumovirus infection cause upper and sometimes lower respiratory tract infections. Respiratory syncytial virus is a very common cause of... read more in infants and young children.

Prognosis for Bronchiolitis

Most children recover at home in 3 to 5 days. However, wheezing and coughing may continue for 2 to 4 weeks. With proper care, the chance of developing serious consequences due to bronchiolitis is low, even for children who need to be hospitalized.

Some children have repeated episodes of wheezing after having had bronchiolitis in early childhood.

Drugs Mentioned In This Article

Generic Name Select Brand Names
BEYFORTUS
Synagis
NOTE: This is the Consumer Version. DOCTORS: VIEW PROFESSIONAL VERSION
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