Abstract
The site of noninvasive measurement of core temperature in human subjects should be selected in order to obtain accurate thermal information for the purpose of the experiments: average deep body temperature or thermal information regarding the central thermoregulatory mechanism.Esophageal temperature (Tes) has been preferably measured for average deep body temperature, since it mirrors closely central blood temperature.Rectal temperature (Tre) renders stable data in a steady state, not being influenced by the outer thermal environment or by shell temperature, but is not appropriate at least in experiments where rapid changes in body temperature are expected, since it is unable to follow relatively rapid changes in blood temperature. Tympanic temperature (Tty) has been measured as an indicator of brain temperature, which is considered to provide the major thermal input to the integrative center for thermoregulation. Intracranial temperature parallels Tty, while their changes are often preceded by those in Tes.The right and left Tty's are not always equal exactly, but may even change in opposite directions in many occasions where uneven blood flow occurs between the cerebral hemispheres, including unilateral cerebrovascular disorders. Regional or unilateral impairment of the balance between heat production in the brain and heat dissipation from it may elicit unevenness or asymmetry in the brain temperature which is reflected in the bilateral Tty's. Measurement of Tty is safe and causes no discomfort, if maneuvered properly. Measurement of aural canal temperature or infrared tympanic thermometry cannot substitute the direct measurement of Tty.Thermoregulatory responses are better correlated with Tty than Tes or other trunk temperatures.
