Infrared Tympanic Thermometry in a Hot Environment

Abstract

The purpose of this study was to compare tympanic (measured by infrared thermometry; Tty-_IRED) with rectal and esophageal temperatures (T_REC and T_ES) during exercise in the heat. During Experiment 1, nine subjects pedaled for 55 min in a hot-dry environment (37 °C; 27 % humidity) in still-air (< 0.2 m/s) and for 10 additional min using water ingestion, wind and ice to cool them down. During Experiment 2, subjects pedaled for 90 min in a similar environment but with airflow at 2.5 m/s. Pearson correlation coefficients (r) and Bland-Altman plots were calculated. In Experiment 1, Tty-_IRED and T_REC were highly correlated (r = 0.83; p < 0.001) with close agreement (− 0.08 ± 0.4 °C). Overall Tty-_IRED was significantly correlated with T_ES (r = 0.91; p < 0.001). Cold water ingestion did not affect Tty-_IRED or T_REC but lowered T_ES. Wind and ice application lowered Tty-_IRED below T_REC (p < 0.05). During Experiment 2, Tty-_IRED was lower than T_REC (p < 0.05) and the difference increased throughout exercise as hyperthermia developed resulting in low agreement (− 1.01 ± 1.1 °C). In conclusion, Tty-_IRED dangerously underestimates T_REC when exercising in a hot environment with airflow or during a cooling treatment. However, it could correctly detect hyperthermia during exercise in a hot still-air environment.

Key words

rectal temperature - skin temperature - indoor exercise - heat illnesses - rehydration

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