Study Questions Efficacy of Popular Forehead Thermometer

Mar. 23 -- FRIDAY, July 13 (HealthDay News) -- A new study is calling into question a widely used, noninvasive method of taking an individual's temperature, but company officials claim the findings were skewed by improper use of the product.

Craig Crandall, a research scientist at the Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, and his colleagues used a body suit filled with hot water to induce heat stress in 16 individuals, 11 of whom were female. They then measured each subject's temperature using both a temporal thermometer made by Exergen Corp., of Watertown, Mass., and an "ingestible pill telemetry system."

A temporal thermometer computes the core body temperature based on forehead temperature, as measured with an infrared scanner. An ingestible pill telemetry system uses a pill-sized device that is swallowed and transmits, from inside the body, a radio signal that correlates to core body temperature.

Crandall's team found that forehead readings were unreliable indicators of core body temperature. Though the two devices reported the same temperature at the start of the experiment, as the subjects' core body temperature (as measured by the ingestible pill) rose, the temporal thermometer readings actually fell. At 50 minutes, for instance, the internally measured temperature had risen about 0.7 degrees C, on average, while the temporal thermometer reported a decrease of about 0.3 degrees C.

The study is published in the July issue of Medicine & Science in Sports & Exercise.

The temporal thermometer "is no better" than the tried-and-true parental method of feeling a child's forehead, concluded Crandall. In fact, "putting your hand on the forehead, in my opinion, is better, because we know the subject is hot, whereas this device actually said a patient was cooling down. So, the hand could actually be more accurate."

However, Exergen President Dr. Francesco Pompei claims the researchers failed to use the product as intended, and that colored the final results.

"The specific concern we had expressed to them two years ago was that they were using the temporal artery thermometer in a manner for which it was not designed and contrary to the manufacturer's instructions ... It was not that they were doing heat stress studies, but that they were conducting them with artificial heating and cooling apparatus, which greatly distorts the thermophysiology of either a patient or an athlete, to the point of little meaning as a laboratory model for actual patients or athletes," Pompei said in a statement.