Bronchiolitis And Asthma

Does Early Wheezing Lead To Asthma?

RSV virus
RSV virus. Photo © ADAM

Bronchiolitis is the most common cause of wheezing in children under asthma. While many physicians still treat the wheezing infant with bronchiolitis like they have asthma, those treatments do not often work. There is also a question as to whether or not the bronchiolitic infant is at increased risk of wheezing and asthma in the future.

What Is Bronchiolitis?

Bronchiolitis is inflammation of the smaller airways of the lungs, called bronchioles, which causes wheezing as air moves in and out of the lungs.

Bronchiolitis usually affects children under 2 years of age during the winter months.

Bronchiolitis is generally caused by one of the following viruses:

  • Respiratory syncytial virus (RSV)
  • Adenovirus
  • Influenza
  • Parainfluenza

Bronchiolitis is usually self-limiting and most infants suffer no long term consequences. Some groups of infants (the premature or those with congenital heart disease) are at risk for complications such as apnea (briefly stopping breathing), severe respiratory distress requiring mechanical ventilation, or bacterial infections.

Are Bronchiolitis and Asthma the Same Thing?

No! Not all that wheezes is asthma, but wheezing should almost always be checked out. If your child has never wheezed and you hear wheezing, you should call your doctor and ask what to do. Some of the viruses listed above can cause your child to wheeze for a couple of weeks and they can lead to what many doctors refer to in adults as "post viral syndrome."

Does Bronchiolitis lead To Asthma?

The respiratory syncytial virus or RSV can lead to symptoms of asthma such as wheezing, chest tightness, shortness of breath and cough. About 4 in 10 children that require hospitalization for bronchiolitis may end up being diagnosed with asthma later in life. However, most kids do not go on to develop the diagnosis.

This can be very difficult to study because of the multifactorial causes of asthma including genetic predisposition, environmental pollutants, and immunological mechanisms.

If your child  has an RSV infection, they are at increased risk of recurrent wheezing and abnormal pulmonary function for the first decade of life. In studies these children are 4 times as likely to wheeze and have decreased respiratory function compared to children that did not have a RSV infection.

Will I Or My Child Wheeze Again? Do I Have Asthma?

The short answer is maybe. About 1 in 3 children who wheeze in the first few years of life will still be wheezing at age 6. The more times you wheeze in a year or requiring steroids are two of the big predictors as well as having a parent with asthma or atopic disease.

What Tests Might My Doctor Order They Suspect Bronchiolitis?

In young children your doctor is not able to perform tests such as FEV1. The most common test your doctor will order will be a chest x-ray. This will help you doctor tell if an infection may be causing the wheezing or if there is some sort of structural problem that is leading to the wheezing.

Can Bronchiolitis be Prevented?

While pediatricians love vaccines, there is not currently a vaccine available to prevent RSV or most of the other viruses causing bronchiolitis. Annual vaccination for influenza is recommended for everyone over 6 months of age. Additionally, everyone living in the household with young infants should be vaccinated.

Decreasing exposure to tobacco smoke, rigorously washing hands, avoiding touching the mouth and nose, and avoiding contact with respiratory illnesses are strategies to decrease risk of contracting or spreading viruses that lead to bronchiolitis.

In the group of infants previously mentioned to be at high risk of complications, palivzumab is given as immunoprophylaxis. This has been shown to decrease the risk of complications from RSV infection. In recent years the qualification for this medication has become significantly more difficult due to its high cost.

Can Bronchiolitis be Treated?

In general routine administration of inhaled bronchodilators such as albuterol have not been found to significantly improve outcomes. This practice not only potentially increases cost of care, but places infants at increased risk of side effects without any real potential for benefit. Oral bronchodilators have commonly been used in the past but also do not provide benefit and are associated with increased risk of side effects. Similarly, acute administration of inhaled steroids has not been found to alter the course of bronchiolitis.

Additionally, neither inhaled steroids or leukotriene inhibitors have been found to prevent subsequent wheezing episodes and are not currently recommended.

 

Your doctor may also order blood tests if they are suspicious for other causes of wheezing.

Sources

1. Castro-Rodriguez J. The Asthma Predictive Index: early diagnosis of asthma.. Curr Opin Allergy Clin Immunol. 2011 Jun;11(3):157–61.

2. National Heart, Lung, and Blood Institute.  Expert Panel Report 3 (EPR3): Guidelines for the Diagnosis and Management of Asthma

3. Medline Plus. . Respiratory syncytial virus (RSV)

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