Ear Thermometers Not So Hot

If accuracy is needed, rectal thermometers are still the best for kids, study says

THURSDAY, Aug. 22, 2002 (HealthDayNews) -- The popular use of the ear thermometer is being challenged.

Despite what you may have heard, the new-age aural gauges aren't as accurate as the old-fashioned rectal types when it comes to taking a child's temperature.

So say British researchers who reviewed a passel of studies comparing the two gauges. They found the ear thermometers come close, but perhaps not close enough, to rectal readings. The researchers stress that doctors, hospitals and parents don't need to throw out their ear thermometers -- they miss the mark from rectal thermometers by an average of only a fraction of a degree centigrade.

However, says Dr. Rosalind L. Smyth, a pediatrician at the University of Liverpool and leader of the research group, when clinical decisions hinge on an accurate temperature reading, rectal is the way to go. Because while the average variation from rectal temperature with the ear devices was .29° centigrade, some studies found that the range of error might be three times as great, or nearly 2° Fahrenheit.

"There are specific clinical situations where one reading would perhaps change a patient's management," Smyth says. For example, children with compromised immunity may require intravenous antibiotics at the first sign of a fever. So, underestimating body temperature might have disastrous consequences.

An accurate measure of fever is also crucial for very young infants, experts say.

Smyth and her colleagues report their findings this week in The Lancet.

The ear thermometer technology works by reading the infrared radiation -- a reflection of heat -- in the ear canal. A computer then converts that information into body temperature.

Ear thermometers have obvious appeal. They can take readings in seconds and present doctors, nurses and parents with a less embarrassing route of temperature measurement. Not surprisingly, nearly two-thirds of pediatricians and family doctors in the United States report using the technology in children.

Smyth's group reviewed 31 studies, involving 4,441 children, comparing rectal and ear thermometers. The ear devices can be programmed to simulate temperatures at various sites in the body, giving readings for the ear canal and the rectum, arm pit and a core figure. So the researchers included studies that included these simulations.

When taken together, the studies showed that ear thermometers consistently varied from rectal readings. They even did so when simulating rectal temperature, though not by as much as the average discrepancy. While the average difference was only .29° centigrade, the highs and lows swung well above and below the average difference.

"We're not saying that people should stop using [ear thermometers]. We feel that in the majority of situations people should continue with the practice they find most comfortable," Smyth says. However, when the most accurate reading possible is needed, rectal thermometers are best, she stresses.

Richard Harbin, a pediatric nurse practitioner at the Indian River County Health Department in Vero Beach, Fla., says he's not surprised by the latest report. "I would agree with the findings," says Harbin, who called the reading differences "a big problem" for health practitioners.

"The manufacturers say that these things are accurate, but most people in practice" prefer rectal thermometers, Harbin says. "If I saw a sick kid come in here and thought he had a fever, I'd use a rectal thermometer" to make sure.

What To Do

For more on ear thermometers, try HowStuffWorks, or ParentsPlace.com.

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