Bronchiolitis

Bronchiolitis is a contagious viral infection of the airways of infants and young children that causes difficulty in breathing, especially breathing out.

Bronchiolitis is most often caused by the respiratory syncytial virus, although other viruses, such as the parainfluenza and adenoviruses, are sometimes involved. Infection with these viruses causes inflammation of the airways. The inflammation causes the airways to narrow, obstructing the flow of air into and out of the lungs.

Bronchiolitis typically affects children younger than 18 months of age and is most common in infants younger than 6 months. During the first year of life, bronchiolitis affects about 11 of every 100 children, although during some epidemics a much higher proportion of infants is affected. Winter and early spring are the peak seasons for bronchiolitis. The disease may be more common in infants whose mothers smoke cigarettes, particularly those who smoked during pregnancy, and it appears to be less common among breastfed infants. Parents and older siblings can be infected with the same virus, but for them the virus usually causes only a mild cold.

Symptoms and Diagnosis

Bronchiolitis starts with symptoms of a cold--runny nose, sneezing, mild fever, and some coughing. After several days, the child develops difficulty breathing, with a worsened cough. Usually the child has a high-pitched sound on breathing out (wheezing). In most infants, the symptoms are mild; even though the infant may breathe somewhat rapidly and be very congested, he is alert, happy, and eating well. Other infants are more severely affected, breathing rapidly, shallowly, and with difficulty. Sometimes the child turns blue from a lack of oxygen. The rapid breathing creates a difficulty in drinking, which may result in dehydration.

A doctor bases the diagnosis on the symptoms and the physical examination. Sometimes the doctor swabs mucus from deep inside the nose to try to identify the virus in the laboratory.

Prognosis and Treatment

Most children recover at home in 3 to 5 days. During the illness, frequent small feedings of clear fluids may be given. Increasing difficulty in breathing, bluish skin discoloration, fatigue, and dehydration indicate that the child should be hospitalized. Children with congenital heart or lung disease or an impaired immune system may be hospitalized sooner and are far more likely to become quite ill from bronchiolitis. With proper care, the chance of dying of bronchiolitis is low, even for children who need to be hospitalized.

In the hospital, oxygen levels are monitored with a sensor on a finger, toe, or an earlobe, and oxygen is given by an oxygen tent or face mask. A ventilator may be needed to assist breathing. Intravenous fluids are given if the child cannot drink adequately. Inhaled drugs that open the airways (bronchodilators) may be tried, although their effectiveness in bronchiolitis is questionable. The antiviral drug ribavirin may be given by nebulizer to infants who are premature or who have other conditions that put them at high risk for severe breathing problems, such as congenital heart or lung disease, cystic fibrosis, or AIDS. Antibiotics are not helpful.