Predicting Deep Body Temperature (Tb) from Forehead Skin Temperature: Tb or Not Tb?

Abstract

There is a need to rapidly screen individuals for heat strain and fever using skin temperature (Tsk) as an index of deep body temperature (Tb). This study’s aim was to assess whether Tsk could serve as an accurate and valid index of Tb during a simulated heatwave. Seven participants maintained a continuous schedule over 9-days, in 3-day parts; pre-/post-HW (25.4 °C), simulated-HW (35.4 °C). Contact thermistors measured Tsk (Tforehead, Tfinger); radio pills measured gastrointestinal temperature (Tgi). Proximal-distal temperature gradients (ΔTforehead–finger) were also measured. Measurements were grouped into ambient conditions: 22, 25, and 35 °C. Tgi and Tforehead only displayed a significant relationship in 22 °C (r: 0.591; p < 0.001) and 25 °C (r: 0.408; p < 0.001) conditions. A linear regression of all conditions identified Tforehead and ΔTforehead–finger as significant predictors of Tgi (r2: 0.588; F: 125.771; p < 0.001), producing a root mean square error of 0.26 °C. Additional residual analysis identified Tforehead to be responsible for a plateau in Tgi prediction above 37 °C. Contact Tforehead was shown to be a statistically suitable indicator of Tgi in non-HW conditions; however, an error of ~1 °C makes this physiologically redundant. The measurement of multiple sites may improve Tb prediction, though it is still physiologically unsuitable, especially at higher ambient temperatures.

Optimal diagnostic fever thresholds using non-contact infrared thermometers under COVID-19

“…In our study, the temperatures at the forehead, temples and wrists measured by NCITs were lower than the axillary temperatures measured by MATs whereas the neck temperature was slightly higher; these results are similar to those of previous studies ( 30 , 39 ). This is obvious because the forehead and temple are bare and are more likely to be affected by ambient temperature.…”

The Physiology of Thermoregulation in Exercise

“…Core temperature is usually determined by an esophageal thermo-sensor, although other methodological aspects have been addressed (5,20,22,62). Nevertheless, the data should be interpreted cautiously, especially when measuring peripheral skin T to estimate core temperature, which is rather questionable (67). On the other hand, there are much more options for assessing skin temperature; besides the above mentioned, infrared thermography has gained increasing importance; yet, similarly to other methods, it has not been standardized (68,69).…”