Tympanic temperatures during hemiface cooling

Abstract

In adult men the left half of the head was covered with thick heat insulation, and the right hemiface was cooled by spraying a mist of water, and vigorous fanning. The subjects were immersed up to the waist in warm water (42 degrees) to achieve hyperthermia. In control sessions the subjects were rendered slightly hypothermic by preliminary exposure to cold. Under the hypothermic condition during right skin cooling, the right Tty remained low as compared with oesophageal temperature, while the left Tty was raised. Under the hyperthermic condition right hemiface cooling maintained not only the right Tty lower than oesophageal but also, to a lesser extent the left Tty, while the skin on the left side was close to core temperature. This latter result cannot be explained by conductive cooling from the skin to the tympanic membrane and implies a vascular cooling of the left Tty originating from the other side of the head. It is concluded that selective cooling of the brain takes place during hyperthermia. The main mechanism is forced vascular convection, but conductive cooling also occurs.

Cerebral Vascular Control and Metabolism in Heat Stress

“…A second theory of SBC in humans, within the scalpsinus pathway, is ostensibly corroborated by the observation that tympanic temperature [used as a surrogate for brain temperature (280)] is reduced by a greater magnitude than esophageal or rectal during local head cooling while heat stressed (51,66,67,318). These findings, however, should be held with caution.…”

Performance in the Heat—Physiological Factors of Importance for Hyperthermia‐Induced Fatigue

“…However, to address this issue Nybo et al (209) investigated cerebral heat balance and measured the internal jugular venous blood temperature as index of the average brain temperature during exercise with and without hyperthermia. The controversial idea that humans, like some animal species, are capable of selectively cooling the brain during hyperthermia arose from the observation that the tympanic membrane temperature may be reduced below other core temperature sites (esophageal or rectal), if active cooling is applied to the head (29,33,34); (185). However, it is important to emphasize that, although the tympanic membrane is located close to the surface of the brain, it is neither a true nor reliable index of the global brain temperature (209,210,284).…”

Effect of bilateral carotid cooling on thermal responses during cycling and arm cranking work due to identical oxygen consumption

“…To estimate T brain in humans, measurement sites other than the brain have frequently been utilized, including the tympanic membrane. T ty is an index of T brain in circulating blood in the brain (Cabanac et al, 1987). We continuously cooled with an ice pack at the bilateral carotid during upper-and lower-body exercise.…”