A novel method to detect heat illness under severe conditions by monitoring tympanic temperature.

INTRODUCTION: We report a new methodology for detecting heat illness based on continuous tympanic temperature monitoring. This is relevant to industrial workers, astronauts, and pilots, as well as athletes. Here we evaluate the method in Grand Touring (GT) car racers in the closed-cockpit category who can face life-threatening hyperthermia.

METHODS: The system comprises an earpiece containing an infrared-radiation-type tympanic thermometer and a microspeaker. In 10 healthy subjects, using a temperature-controlled water bath in the laboratory, we determined the differences in measurements taken from an infrared thermometer in one ear canal and from a thermistor probe in the other ear canal for direct tympanic temperature measurement. We employed an ingestible telemetry pill for gastrointestinal temperature measurement as a reference of core temperature. Then we assessed the usefulness of the system under real racing conditions with two professional drivers in the 2010 Super GT International Series held at the Twin Ring Motegi in Japan.

RESULTS: The results showed a good correlation between the infrared tympanic temperature and both the direct one (r = 0.985) and the gastrointestinal temperature (r = 0.932). The mean difference between these temperatures was +0.01 degree C and +0.27 degrees C, with 95% confidence intervals (equal to 1.96 SD) of 0.30 degrees C and 0.58 degrees C, respectively. As for the field test, the system functioned well during real competitive and extremely severe race conditions on the racing circuit.

CONCLUSIONS: The new method was found to perform well in an extreme car racing setting. It has the potential to be used in other applications, including the industrial and aerospace sectors.