Croup

Once our children return to their classrooms, the respiratory viruses begin flying and kids once again get sick. As a matter of fact, we have already begun to see some viral respiratory illnesses beginning to rear their ugly heads. One illness which we have seen twice this week is croup. In speaking with the parents of these patients, I am reminded of the misconceptions surrounding this disease, so I thought it might be time once again for a review of this common ailment.

The medical term for croup is laryngotracheobronchitis or LTB. Remembering our word derivations, this simply means inflammation (itis) of the voice box (laryngo), wind pipe (tracheo) and breathing tubes (bronchi). With inflammation comes swelling, and when swelling is severe enough, obstruction results. Kids with croup get into trouble when the obstruction is severe enough to cause symptoms.

The narrowest part of the pediatric airway in its normal state is the area just below the vocal cords. In adults, the airway is narrowest at the vocal cords. Also, remember that the pediatric airway is much softer and more compressible than its adult counterpart.

When organisms like the parainfluenza virus infect the pediatric airway, the entire airway swells. Since the area under the vocal cords is already narrow, it is the most affected. As it swells, it becomes more difficult for the child to move air through this opening.

As the child struggles to breathe, he or she needs to "suck" harder than usual which tends to collapse the relatively compressible airway, making the obstruction even worse. Also this forced breathing through a narrow tube creates the characteristic stridor sound we hear in kids who have croup. It is also responsible for the barking, seal like cough, known to occur in these children.

Although it sometimes seems as if these symptoms come on suddenly, often in the middle of the night, it is actually a relatively gradual process that only becomes a problem when the obstruction is critical. Children can occasionally become anxious and even panicky when it becomes difficult to breathe. The anxiety and forced breathing associated with it can also contribute to worsening the symptoms.

Treatment is directed at reducing this swelling. Sometimes this can be as simple as taking the child out into the cool night air. The change in atmosphere may be just enough to reduce the swelling to a tolerable level. Taking the child into the shower is known to have the same result. When this fails, medicines can be used. Racemic epinephrine combined with inhaled steroids works immediately and is extremely effectively.

Occasionally, when repeated treatments are required to keep the swelling in check, the child may need to be admitted to the hospital for closer observation and more aggressive treatment.

Very rarely, the obstruction is severe enough to cause respiratory failure. When this occurs an endotracheal tube (a "breathing tube" that's usually inserted through the nose and into the lungs) must be placed. When the tube is inserted, the patient must be placed on the ventilator to breath. Once the swelling diminishes, the tube is removed and the child returns to normal.

Croup is a common but easily treatable condition. Understanding the pathophysiology behind that classic seal-like cough may help us to know when, and how to intervene.

John E. Monaco, M.D., is board certified in both Pediatrics and Pediatric Critical Care. He lives and works in Tampa, Florida. His column appears every month. He welcomes your comments, suggestions, and criticisms.

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