Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at May 25, 2016

Bronchiolitis affects the smallest airways in the lungs known as the bronchioles. Bronchioles are the tiny passages that form branches and manage the flow of air in the lungs. Inflammation of the bronchioles occurs most often among young children as a result of viral infection.


Definition & Facts

Bronchiolitis is the term used for inflamed bronchioles. As the bronchioles swell, they become blocked or clogged. Oxygen will no longer move freely through the lungs. The most common form of bronchiolitis affects young children, especially infants and often occurs during the winter months. This type of bronchiolitis is commonly caused by viruses, especially the human respiratory syncytial virus.

In rare cases, bronchiolitis obliterans may affect adults. This type of bronchiolitis is much more severe because it causes a permanent buildup of scar tissue in the bronchioles. Bronchiolitis obliterans is linked to organ transplantation, a variety of viral infections, and exposure to environmental toxicants among other causes.

Symptoms & Complaints

Regardless of what type of bronchiolitis a patient has, there are telltale symptoms that indicate a problem that originates in the lungs. Patients with bronchiolitis tend to wheeze and have a hard time catching their breath.

There may be a rattling sound deep down in the chest each time a patient with bronchiolitis takes a breath and the skin may take on a blue tint due to deprivation of oxygen. The rate of breathing may increase as the patient attempts to take in more oxygen. Bronchiolitis typically causes patients to become extremely fatigued because they are not getting an adequate supply of oxygen.

Whooping cough often goes hand in hand with inflammation of the bronchioles. For infants, nasal flaring and a sunken chest when attempting to breathe in are other indicators that bronchiolitis may be the source of the problem. Adults with bronchiolitis may not exhibit symptoms until some time after a respiratory tract infection has developed or there has been exposure to an environmental hazard.


Bronchiolitis is typically triggered by viruses that make their way into the respiratory system. These viruses are often inhaled, microscopic, and quickly multiply. Several types of viruses are typically connected to bronchiolitis. Human respiratory syncytial virus, also known as RSV, is the virus that most commonly causes bronchiolitis in infants. In rarer cases, children develop bronchiolitis due to adenoviruses. These viruses attack the mucous membranes and can have a domino affect on the bronchioles. The influenza viruses can also be connected to bronchiolitis when they affect the throat, the lungs, and the nose.

Infants that are at the greatest risk of developing bronchiolitis include those who are premature, are sent to daycare with many other children, are exposed to secondhand smoke from cigarettes, or have some type of underlying condition that affects the lungs and the immune system.

Bronchiolitis obliterans is connected to chemical exposure, problems with medication, and as a complication of respiratory infections, among other causes. Adults are at a higher risk of developing bronchiolitis obliterans if they work with toxic chemicals on a regular basis and do not take the necessary precautions to protect their lungs. Adults with connective tissue conditions or transplant patients for bone marrow, the lungs, and the heart may also be prone to developing bronchiolitis.

Diagnosis & Tests

Bronchiolitis is usually diagnosed through the use of imaging tests. Chest X-rays are helpful in determining if bronchiolitis is the root of the problem. Doctors often use spirometry when evaluating adult patients. This is a measurement of the rate of each inhalation. The amount of oxygen in the blood can be measured through a blood gas test. This type of test will measure the amount of carbon dioxide as well.

A doctor may also collect mucous samples in order to identify the type of virus that is connected to bronchiolitis in order to develop a more effective form of treatment. A physician will consider all data, including symptoms, risk factors, and test results in order to deliver a diagnosis of bronchiolitis.

Treatment & Therapy

For mild forms of bronchiolitis, rest and plenty of fluids may be recommended while the virus runs its course. However, hospitalization is recommended for young infants who have more severe cases of the illness. While antibiotics will not affect most cases of bronchiolitis that stem from viral infections, a hospital can provide medical supervision and oxygen for babies in order to maintain their stable condition. Intravenous medication may be necessary in order to help infants breathe more easily. They can also be provided with intravenous hydration and nourishment while the illness lingers.

Adults with bronchiolitis obliterans are typically given oxygen, corticosteroids that can relieve inflammation, and medication that is intended to strengthen the immune system. Because the scarring in the lungs is permanent and progressive, it may be necessary to train adult patients how to breathe more effectively. In the most severe cases, doctors may recommend a lung transplant.

Patients with bronchiolitis need plenty of rest and fluids in order to remain hydrated. It is essential that there is good air quality in the home. Cigarettes should not be allowed inside and chemicals should not be sprayed near the patients or in their homes. Keeping the air moist can be helpful in keeping patients comfortable. 

Prevention & Prophylaxis

There are steps that can be taken to reduce the risk of developing bronchiolitis. Keeping hands clean with repeated washing is a must. Adults handling infants should always take care with good hygiene. If caregivers for infants have a respiratory infection, they can wear a mask to avoid exposing babies to viral infections.

Keeping the home or childcare center disinfected is a helpful precaution as well. Infants should not be exposed to a large number of people, especially those who are ill. Breastfeeding is linked to a stronger immune system and may help infants to stave of bronchiolitis.

For adults that are trying to avoid bronchiolitis obliterans, it is important to avoid inhalation of chemicals by following safety precautions at work and at home. Maintaining a healthy environment, washing hands, and not sharing drinks can reduce the risk of compromising the immune system for adults who have underlying conditions.