Theoretical evaluations of therapeutic systemic and local cerebral hypothermia

Treatment of Resistant Fever: New Method of Local Cerebral Cooling

“…Regarding the short-term temperature increase in our patients after the same delay time after the start of the neck pad device application, spontaneous fever variations seem to be unlikely. The hypothesis of a counterregulation provoked by treatment of fever was discussed by Keller et al [13] based on the mathematical models. The origin and mechanisms of thermoregulation of brain and body are very complex and the exact causes of set-point changes are discussed controversially [19][20][21].…”

“…Corresponding to our mathematical simulations, the heat transfer coefficient (htc) in these pads was about 22.4 watts per meter squared-kelvin (W/(m 2 K)) with a mathematical optimal htc of 28 W/(m 2 K). Tissue density, tissue specific heat coefficients, blood perfusion rate, heat source of the natural metabolism, and further values were implemented in the mathematical equation representing the thermal behavior of the different tissues and blood, which was developed in the previous study [13] and transferred in this practical observational study. The ArcticSun Ò Temperature Management System (Medivance, Louisville CO) was used, employing hydrogel-coated water-circulating energy transfer pads to allow an intimate adhesion to the patient's skin and a similar heat exchange coefficient as in a water bath [16].…”

“…Compared to an intravascular cooling method, which is efficient and fast, but invasive and with several relevant side effects such as venous thrombosis or cause of infections, the advantage of a local cooling device becomes obvious. For specific cooling of the deep brain, head caps are not efficient [12][13][14], whereas neck pads covering bilateral the carotid triangle decrease the brain temperature in a mathematical simulation [13,15]. In a previous study, we simulated cerebral temperature behavior by applying different cooling devices [13].…”

“…For specific cooling of the deep brain, head caps are not efficient [12][13][14], whereas neck pads covering bilateral the carotid triangle decrease the brain temperature in a mathematical simulation [13,15]. In a previous study, we simulated cerebral temperature behavior by applying different cooling devices [13]. They simulated cerebral temperature behavior with hypothermia treatment applying different cooling devices.…”

“…Cooling with head caps lead to 33°C only in the superficial brain, while the deep brain remains higher than 36°C. In contrast cooling with neck pads, covering the carotid triangles, lead to 35.8°C for dry, and 32.8°C for wet skin in the deep brain within 6 h. The equation of the mathematical model included temperature-dependent blood perfusion, cerebral metabolic rate, and time-dependent arterial blood temperature [13].…”