Theoretical evaluations of therapeutic systemic and local cerebral hypothermia.

PURPOSE

To simulate cerebral temperature behaviour with hypothermia treatment applying different cooling devices and to find the optimal brain temperature monitoring.

METHODS

Models based on hourly temperature values recorded in patients with severe aneurysmal subarachnoid hemorrhage, taking MRI data, thermal conductive properties, metabolism and blood flow into account were applied to different scenarios of hypothermia.

RESULTS

Systemic hypothermia by endovascular cooling leads to an uniform temperature decrease within the brain tissue. Cooling with head caps lead to 33 degrees C only in the superficial brain while the deep brain remains higher than 36 degrees C. Cooling with neckbands lead to 35.8 degrees C for dry and 32.8 degrees C for wet skin in the deep brain.

CONCLUSIONS

With head caps temperatures below 36 degrees C cannot be reached in the deep brain tissue, whereas neckbands, covering the carotid triangles, may lead to hypothermic temperatures in the deep brain tissue. Temperature sensors have to be applied at least 2 cm below the cortical surface to give values representative for deep brain tissue.