Bronchiolitis is a lung infection that affects children of any age; however, it is much more severe when it occurs in young infants.


The bronchioles are small branches off of the more major bronchi or airway tubes that run through the lungs. When these bronchioles are infected, they become inflamed, and breathing may become difficult.

Bronchiolitis is a particularly important problem in babies who are born prematurely or who have other chronic medical illness. These children are at greatly increased risk of contracting bronchiolitis and of having a more severe course of the illness. Bronchiolitis is the most common reason that babies are hospitalized in the winter. Most cases of bronchiolitis occur between the months of December and May.


Every year, 1–2 percent of all babies under 12 months of age require hospitalization due to bronchiolitis. At highest risk are boys, premature infants, infants living in urban locations, babies who have not been breastfed, and babies with chronic pulmonary, cardiac, or immune conditions.

Causes and symptoms

Most cases of bronchiolitis are caused by viruses, the most common of which is respiratory syncytial virus. Other common viral causes include parainfluenza, influenza , and adenovirus. Like most types of respiratory viruses, the viruses that cause bronchiolitis are usually contracted through breathing in infected droplets that are sprayed out by another ill individual during coughing or sneezing.

Most cases of bronchiolitis start with symptoms of a cold: sneezing, runny nose, fatigue, decreased appetite, fever . After two or three days of these symptoms, the bronchiole inflammation becomes severe enough to cause cough , wheezing, and rapid breathing.

Severely ill babies or children show signs of difficulty breathing. Their neck muscles and the muscles between their ribs will contract with each effort to breathe, and their chest may cave in as well. Smaller babies may make grunting sounds as they struggle to take in air. Babies will have difficulty nursing or taking bottles and may not be able to feed at all.

When to call the doctor

A doctor should always be called when a child appears to be in any respiratory distress. Fast breathing rates, wheezing, abnormal muscle contractions, or a blue cast to the lips or fingernails should all alert the parent that the child is having difficulty breathing and should be seen immediately by a healthcare provider.


Initial diagnosis of respiratory distress is made based on clinical signs of difficulty breathing. A pulse oximeter or arterial blood gas measurement reveals the presence of decreased oxygen in the blood. Chest x rays may show characteristic patterns of lung involvement. Nasal swabs can be taken in order to identify the causative viral agent, although viral culture takes long enough that the patient is usually on the way to recovery by the time the viral agent has been identified.


Treatment at home should consist of acetaminophen for fever and comfort (not aspirin, which has been implicated in Reye's syndrome in children), increased intake of liquids, and a cool water vaporizer. The utility of asthma medications, like bronchodilators, is as of 2004 still undecided.

Children who require hospitalization receive fluids intravenously and supplemental oxygen through a mask or nasal cannulae (small tubes into the openings of the nostrils). Ten percent of all hospitalized infants require mechanical ventilation. Children who are severely ill may be given antiviral medications, such as ribavirin, which is thought to shorten the length of illness and decrease its severity.


Most children recover uneventfully from bronchiolitis, although some studies have suggested that children who have had bronchiolitis may be at higher risk for reactive airway disease throughout the remainder of their lives.


Bronchiolitis is spread the same way that most other respiratory viruses are communicated, through droplets and contact with infected nasal secretions. Good hand washing is paramount to prevention, as is keeping children out of public places while they are acutely ill and coughing and sneezing.


Bronchiole —Tubes in the lungs that carry air from the bronchi to lung tissues.

Parental concerns

A doctor should always be called when a child appears to be in any respiratory distress. Severe breathing difficulties need immediate medical treatment. Parent should educate their children about good personal hygiene to avoid spreading the germs that cause colds and bronchiolitis.



Goodman, Denise. "Inflammatory Disorders of the Small Airways." In Nelson Textbook of Pediatrics , edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.

Lazarus, Stephen. "Disorders of the Intrathoracic Airways." In Textbook of Respiratory Medicine , 3rd ed. Edited by John F. Murray and Jay A. Nadel. Philadelphia: Saunders, 2000.

Tristram, Debra A., and Robert C. Welliver. "Bronchiolitis." In Principles and Practice of Pediatric Infectious Diseases , 2nd ed. Edited by Sarah S. Long et al. St. Louis, MO: Elsevier, 2003.


Davison, C. "Efficacy of interventions for bronchiolitis in critically ill infants: a systematic review and meta-analysis." Pediatric Critical Care Medicine 5 (September 2004): 482–3.

Dayan, P. "Controversies in the management of children with bronchiolitis." Center for Pediatric Emergency Medicine 5 (March 2004): 41.

Steiner, R. W. "Treating acute bronchiolitis associated with RSV." American Family Physician 86 (January 2004): 325–30.

Rosalyn Carson-DeWitt, MD

Also read article about Bronchiolitis from Wikipedia

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