Bronchiolitis is inflammation of the small airways in the lungs. Acute bronchiolitis is due to a viral infection usually affecting children younger than two years of age. Fever, cough, runny nose, wheezing, and breathing difficulties are common symptoms. Severe cases may show signs of nasal flaring, grunting, or chest retractions while breathing. If the child has not been able to feed properly, signs of dehydration may be present.

Chronic bronchiolitis is the general term used for small airways disease in adults, notably in chronic obstructive pulmonary disease.

Acute bronchiolitis is usually the result of infection by respiratory syncytial virus (72% of cases) or human rhinovirus (26% of cases). Diagnosis is generally based on symptoms. Tests such as a chest X-ray or viral testing are not routinely needed.
Bronchiolitis and RSV

Bronchiolitis is commonly caused by respiratory syncytial virus (RSV). RSV is a highly contagious virus that can cause severe illness in young children, especially infants, and those with compromised immune systems. Symptoms of bronchiolitis include wheezing, coughing, rapid breathing, and difficulty breathing. Treatment is mainly supportive, including providing fluids and oxygen as needed, and medications to relieve symptoms. Prevention includes frequent hand washing, avoiding close contact with infected individuals, and getting the RSV vaccine. ( see RSV click here)

There is no specific treatment. Symptomatic treatment at home is generally sufficient. Occasionally, hospital admission for oxygen, support with feeding, or intravenous fluids is required. Tentative evidence supports nebulized hypertonic saline. Evidence for antibiotics, antivirals, bronchodilators, or nebulized epinephrine is either unclear or not supportive.

About 10% to 30% of children under the age of two years are affected by bronchiolitis at some point in time. It commonly occurs in the winter in the Northern Hemisphere. It is the leading cause of hospitalizations in those less than one year of age in the United States. The risk of death among those who are admitted to hospital is about 1%.

Signs and symptoms

Bronchiolitis typically presents in children under two years old and is characterized by a constellation of respiratory symptoms that consists of fever, rhinorrhea, cough, wheeze, tachypnea and increased work of breathing such as nasal flaring or grunting that develops over one to three days. Crackles and wheezing are typical sounds heard when a stethoscope is used to listen to the chest. A child may also have brief pauses in breathing, known as apnea. The airways often remain sensitive for several weeks after the acute illness, causing a recurring cough and wheeze.

Some signs of severe disease include:

  • increased work of breathing (such as use of accessory muscles of respiration, rib & sternal retraction, tracheal tug)
  • severe chest wall recession (Hoover’s sign)
  • presence of nasal flaring and/or grunting
  • increased respiratory rate above normal.
  • hypoxia (low oxygen levels)
  • cyanosis (bluish skin)
  • lethargy and decreased activity.
  • poor feeding (less than half of usual fluid intake in preceding 24 hours)
  • history of stopping breathing

Risk factors

Children are at an increased risk for progression to severe respiratory disease if they have any of the following additional factors:

  • Preterm infant (gestational age less than 37 weeks)
  • Younger age at onset of illness (less than 3 months of age)
  • Congenital heart disease
  • Immunodeficiency
  • Chronic lung disease
  • Neurological disorders
  • Tobacco smoke exposure


Bronchiolitis therapy typically involves supportive care, such as:

  • Plenty of fluids
  • Humidification
  • Pain relief (e.g. acetaminophen)
  • Monitoring for complications.
  • Oxygen therapy

In severe cases, oxygen therapy may be required. Nebulized bronchodilators and corticosteroids are not recommended as routine therapy for bronchiolitis.

Oxygen therapy, which involves providing supplemental oxygen to the patient, may be required in severe cases of bronchiolitis to help alleviate breathing difficulties. An oxygen concentrator is a device that concentrates ambient air into oxygen-rich air, and is often used for home oxygen therapy. (see oxygen therapy click here)