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High Humidity Doesn't Ease Croup

Cold air and medical treatments probably more effective, study suggests

TUESDAY, March 14, 2006 (HealthDay News) -- A time-honored treatment to ease the seal-like bark of croup is to bring your child into a steamy bathroom or run a cool-mist vaporizer in her room until symptoms subside.

However, a new study suggests that these measures probably won't have much effect on croup symptoms.

"The use of humidity failed to show any improvement in croup symptoms," said the study's lead author, Dr. Dennis Scolnik, an associate professor at the Hospital for Sick Children and the University of Toronto in Canada.

Results of the study appear in the March 15 issue of the Journal of the American Medical Association.

Croup, which is the swelling of the tissues around the voice box, is actually a response to a viral or bacterial infection rather than a distinct illness. Croup is characterized by a cough that often sounds like the bark of a seal. Sometimes, the inflammation can get so bad that it obstructs the airway.

Croup caused by viruses is one of the most common causes of upper airway blockage in youngsters, affecting as many as 5 percent of children under 6 years old, according to the study.

The idea behind the use of humidity is that the moisture would soothe the irritated airway and thin mucous secretions, making breathing easier. However, Scolnik said there's no good scientific evidence available to support the use of humidity.

To put this theory to the test, Scolnik and his colleagues randomly divided a group of 140 children diagnosed with moderate to severe croup into three treatment groups. One group, the control group, received "blow-by" humidity for 30 minutes. According to the study, the amount of humidity in the blow-by technique is variable and often equivalent to room air. A second group received controlled delivery of 40 percent humidity, and the third group was treated with 100 percent humidity.

Symptoms were assessed at 30 minutes and 60 minutes after treatment. The researchers found no statistically significant differences between the groups.

"I think it's important that parents not rely on a treatment which we don't think helps," said Scolnik.

Why then, do so many people rely on humidity and believe that it helps?

Probably because croup symptoms often go away on their own with no treatment at all, said Scolnik.

"The illness has a tendency to get better, and if it gets better while you're giving humidity, you'll think it was the humidity," he said, adding that another likely scenario is that while administering humidity to children, parents often sit with them and try to calm them. As they calm the child, some of the coughing and crying stop. The worst symptoms probably have some component of airway spasm, said Scolnik, so calming a child would help relieve those spasms, making breathing easier.

Not everyone is convinced, however, that there is no place for humidity in croup treatment.

"This is a good study, but it's not going to change anything here," said Dr. Mehmet Karliyil, a pediatric emergency physician at Nyack Hospital in Nyack, N.Y.

"Humidity is useful. What this study shows is that 40 percent isn't any more effective than 100 percent," said Karliyil, who added that just means more humidity isn't better.

Both Scolnik and Karliyil said that other treatments are available for croup. Going out into the cold night air, or opening a window and breathing in the cold air may help shrink swollen airways, said Scolnik.

Doctors can also prescribe steroid medications or inhaled epinephrine to lessen inflammation, he added.

Karliyil said it's a good idea to take your child to the doctor the first time he has croup to confirm the diagnosis and make sure nothing else is wrong. After that, parents don't need to immediately go to the doctor at the first sign of croup, he said.

Both experts said at the first sign of breathing trouble, you should seek medical attention, either at the doctor's office, at the emergency room, or by calling 911.

More information

To learn more about croup, visit the National Library of Medicine.

SOURCES: Dennis Scolnik, M.B., Ch.B., associate professor, Hospital for Sick Children and University of Toronto, Canada; Mehmet Karliyil, M.D., pediatric emergency physician, Nyack Hospital, Nyack, N.Y.; March 15, 2006, Journal of the American Medical Association
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