If you wake up to the familiar barking cough of croup all too often, you might wonder why your baby so frequently develops croup or what you can do to prevent it. Croup is one of the most common respiratory infections in small children, accounting for 15 percent of all emergency room visits for respiratory causes in children, Dr. Roger Zoorob, professor of family medicine at Meharry Medical College, reports. Abnormalities of the trachea and larynx, as well as other medical conditions, can cause recurrent bouts of croup.
Causes of Croup
Many cases of croup start with an upper respiratory infection that leads to inflammation and swelling in the voice box, or larynx and trachea. This narrows the air passage to the lungs, which causes the vocal cords to vibrate with the increased turbulence of air flow through the narrowed passage. This causes the stridorous breathing, hoarse voice and barking cough associated with croup. Spasmodic croup, which develops without a fever or cold symptoms, can recur, according to the American Academy of Pediatrics. Children with spasmodic croup often have allergies or acid reflux that trigger their symptoms.
Babies have extremely narrow tracheas; anything that narrows the trachea by even a small amount impedes the flow of air to the lungs. If inflammation causes as little as 1 millimeter of edema in the trachea, it reduces air flow by 35 percent, according to the Children's Hospital of Wisconsin website. Some children have a trachea that's even narrower than normal, with no other abnormalities, which increases their susceptibility to croup. Children with asthma or other chronic lung disorders, such as cystic fibrosis, or children with neuromuscular diseases, such as cerebral palsy, have a higher risk of developing croup, experts with the Kids Health website explain.
Other Possible Diagnoses
A baby with recurrent croup could have subglottic stenosis, a congenital or acquired narrowing of the airway above the trachea and below the vocal cords. In a Wayne State University School of Medicine study of children with recurrent croup published in the November/December 2007 issue of the American Journal of Otolaryngology, 100 percent had some degree of subglottic stenosis, ranging from 15 to 70 percent airway narrowing. Sometimes what's diagnosed as recurrent croup isn't really croup. Other disorders can cause stridor and hoarse breath sounds, including subglottic hemangiomas, normally diagnosed before the age of 3 months, respiratory papillomas or vocal cord paralysis, according to the Children's Hospital of Wisconsin website.
Viruses most often cause croup, so antibiotics generally do nothing to prevent or treat it, although they can prevent superimposed bacterial infections from complicating the illness. If your doctor suspects spasmodic croup, he might prescribe allergy or reflux medications to reduce episodes. When your baby suffers from a croup attack, her doctor might prescribe steroid medications to reduce the severity of the edema in the trachea.