All about croup
Croup 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 upper 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. Although we have a vaccine for influenza, there is no vaccine to prevent parainfluenza; in spite of the similarities in their names, the two viruses are not related at all. 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. Here’s a neck x-ray of a child with croup. You can see with the arrow how narrow the airway, which on x-ray is a black air column, can be — often just a millimeter or so in diameter in more severe cases.
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 and it helps with the throat pain. Croup generally occurs during the colder weather months. Another old remedy is to take the child out into the cold night air for a few minutes. I’m not sure why, but I think this actually helps, perhaps because cold shrinks the inflamed airway tissues. Inhaling a mist of the drug epinephrine definitely shrinks the swollen tissues, although it only lasts for an hour or two. The steroid drug dexamethasone, either orally or by injection, has become a standard therapy for moderately severe croup and it is quite effective because steroids reduce swelling. This therapy takes a couple of hours to work, though, because it needs to work its way into the tissues via the blood stream to exert its effects. More recently we’ve sometimes used inhaled steroids delivered as a mist, and that has been shown to improve the situation by directly delivering the steroid to the the affected area. 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, termed stridor at rest, or if there are any retractions present — both of these are indications for an evaluation and possible therapy with epinephrine or dexamethasone. Another reason would be if your child refuses to drink enough. If your child has fever and drooling, refusing to swallow, as well as difficulty breathing that could be a much more serious infection called epiglottitis. That requires immediate attention in the emergency department.
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 to bypass the obstruction until it clears on its own. Nearly all children, however, recover from croup with no complications.