Bronchiolitis: A common respiratory illness during a baby’s first year

Your baby will (unfortunately) contract six colds, on average, during his first year. Most colds will have upper respiratory symptoms (runny or stuffy nose, perhaps a cough, possibly a fever). Most colds will last for 5-10 days (yes, it takes longer for babies to shake a cold than an adult. Also, the baby’s symptoms are much more obvious since they cannot blow their nose, and they let you know when they are not feeling their best).

Occasionally, some colds have a “Stage Two” attached.
There are three common “Stage Two” parts of colds: some babies will get an ear infection after a cold (due to physiologic anatomy and nasal congestion), some cold viruses will result in a body rash (“viral rash”) one or two weeks after the cold virus has resolved, and finally, some colds will travel lower in the baby’s respiratory tract and continue on into a Croup or Bronchiolitis. Croup is more common in 1-2 year olds. Bronchiolitis is more common during a baby’s first year.

So, think of bronchiolitis as “part two” of a cold. The cold virus unfortunately has moved lower in the baby’s respiratory tract, to the smallest of the airway branches, called the bronchioles. An adult typically gets “bronchitis” from a chest cold (inflammation of the bronchi), but an infant gets “bronchiolitis” – inflammation of the smaller branches of the respiratory system.

These respiratory infections are unique in that they typically impact infants and toddlers, but not adults. However, the very same virus that may cause a basic cold in anyone, a “head cold” or “chest cold” for others in the home, may result in croup or bronchiolitis in an infant or toddler. It’s not the virus itself that causes the bronchiolitis (or croup, or ear infection), rather, the virus causes the infection, and the infection progresses to a symptom in the bronchioles (or middle ear).

Bronchiolitis is an infection of the respiratory tract that affects the smallest airways of the lung. The swelling and obstruction of these tiny airway passages creates shortness of breath, wheezing or whistling noises. You might notices an infant with bronchiolitis is working harder, with rapid, shallow breathing, with neck or chest “accessory muscles” moving with the breathing efforts.  You’ll likely notice more irritability or crankiness, restlessness and decreased appetite as the body’s efforts must go into breathing and oxygenation rather than eating and nutrition.

Since the virus that causes bronchiolitis is often the same virus that causes the common cold, you may see cold symptoms including a runny or stuffy nose, cough and fever. Bronchiolitis or croup may start with a common cold, but progress to the lower respiratory tract.

Even if your baby doesn’t seem to be struggling to breathe, restlessness may be a sign of low oxygen levels in an infant, so it’s worth a call to your pediatrician if your baby has a fever, congestion, is breathing rapidly and seems very unsettled or unhappy. It’s better to call and be told what to watch for, than worry about if you should call or not!

Bronchiolitis is most common in the winter and spring but may occur at any time. It is most common in babies under a year old, boys are more commonly affected and exposure to smoke, daycare or older siblings makes a baby more likely to get more frequent colds, so also increase the risk or rate of bronchiolitis. Avoiding obviously sick people (hard to do in daycare where seemingly 75% of children appear to have some stage of a cold!) and good hand washing are always good practices to reduce risk of catching a cold or virus.

RSV (respiratory syncytial virus) is the most common viral cause of bronchiolitis (though the flu virus or a regular rhinovirus – the common cold virus – may also result in bronchiolitis in an infant). Premature and other vulnerable infants are more susceptible to RSV, or may have a harder time managing RSV illnesses, so some higher-risk babies may receive a vaccine to prevent RSV.

Your pediatrician will diagnose bronchiolitis by listening to your baby’s chest, checking a pulse oximetry oxygen level and perhaps ruling out pneumonia or another diagnosis by requesting a chest x-ray. Presense of the RSV virus may be confirmed using a nasal swab in the pediatrician’s office.

Treatment for bronchiolitis will depend on your baby’s specific symptoms and severity. Most bronchiolitis cases are mild and will be cared for at home by offering fluids, anti-fever medications, and using a humidifier and saline nose drops to keep breathing more comfortable. Occasionally “nebulizer” breathing treatments may be done in the doctor’s office or at home. Rarely, a baby may need to be briefly hospitalized for breathing treatments or extra oxygen but this is not typical at all. Antibiotics will not help bronchiolitis, which is the infant’s respiratory response to a virus similar to a cold.