It’s that time of the year in the PICU for more respiratory illnesses, one of them being croup. This is an ancient illness — its very name comes from the Anglo-Saxon word to croak, which is what children with croup can sound like. The characteristic brassy cough sounds more like a seal to our modern ears, though. Also characteristic is a sound we call stridor, the sound of air rushing through a narrowed tube, in this case the child’s airway.
Croup is caused by viral infection of the region just below the vocal cords. One of several viruses can do it, but the usual offenders are members of the parainfluenza group. The infection causes swelling, and the swelling causes narrowing of the airway. This makes it more difficult for the child to breath — in some ways it is like breathing through a straw — and the child has to work harder to get air in. This can make the child’s chest cave in the wrong way with each breath, something called retractions. Fever, if present, is usually mild.
As with most viral illnesses, there is no specific treatment for croup — what treatment we have is directed at relieving the symptoms of throat pain and difficulty breathing. We do have several effective ways of doing this. Simple mist, as from a steamy bathroom, is a time-honored therapy to help a child breath. Inhaling a mist of the drug epinephrine shrinks the swollen tissues, although it only lasts for an hour or two. The drug dexamethasone, either orally or by injection, has become a standard therapy for moderately severe croup and it is quite effective. Acetaminophen or ibuprofen can treat fever and throat pain.
When should you bring your child to the doctor for croup? A good rule of thumb is if your child has stridor when sitting quietly or if there are any retractions present — both of these are indications for therapy with epinephrine or dexamethasone.
We always see a few children in the PICU with severe croup, usually those who need repeated doses of epinephrine or are working very hard to breath. On very rare occasions we need to use a breathing tube and a mechanical ventilator for these children. Nearly all children, however, recover from croup with no complications.
I’ve written a more detailed discussion of croup, which includes an x-ray of what it looks like and some uncommon causes of airway obstruction, in a Google Knol here. (A glitch in the Google software refuses to list my name as the author; I’ve given up trying to fix it.)