[The "ear fever thermometer"--studies of ear thermography]

Though rarely mentioned in the ENT literature, the "ear thermometer" has become more and more popular in recent years, not only in hospitals but also in households. These instruments are easy to use, and their infrared technology is said to provide precise measurements. The purpose of this study was to verify these claims.

Infrared thermometers were tested in various conditions, and the results were compared. We assessed the effects of "distending" the outer ear canal, different body positions, and irritation of the ear (slight external otitis, hearing aids, otitis media, etc.). We did not specifically test effects of ear wax, as it had sufficiently been studied in pediatric or anesthesiological papers before (almost no effect, except in cases of occlusion of the auditory canal).

Using the ear thermometer we found small but statistically significant differences in febrile patients in different body positions. Irritated ears always showed higher temperatures than the normal contralateral ears. The most significant differences were found in persons lying on one side. The "pillow ear" was found 0.7 degree C (average) warmer than the contralateral ear.

Ear thermometers for estimating the body temperature permit easy and fast measurements. However, they include possible sources of measurement error. This study describes possible errors that the therapists should be aware of to avoid misinterpreting the course of a disease.