Brain hypothermia induced by cold spinal fluid using a torso cooling pad: theoretical analyses

Abstract

Brain hypothermia induced by a temperature reduction of the spinal fluid using a torso-cooling pad is evaluated as a cooling alternative for traumatic injury patients. A theoretical model of the human head is developed to include its tissue structures and their contribution to local heat transfer. The Pennes bioheat equation and finite element analysis are used to predict the temperature distribution in the head region. The energy balance in the cerebrospinal fluid (CSF) layer surrounding the brain during mixing of the CSF and cold spinal fluid is also formulated to predict the CSF temperature reduction. Results show that the presence of cooled CSF around the brain provides mild cooling (approximately 1 degrees C) to the grey matter within 3000 s (50 min) with a cooling capacity of approximately 22 W. However, large temperature variations (approximately 3.5 degrees C) still occur in the grey matter. This approach is more effective during ischemia because it promotes deeper cooling penetration and results in larger temperature reductions; the average grey matter temperature decreases to 35.4 degrees C. Cooling in the white matter is limited and only occurs under ischemic conditions. The non-invasive nature of the torso-cooling pad and its ability to quickly induce hypothermia to the brain tissue are beneficial to traumatic injury patients.

Experimental study and model validation of selective spinal cord and brain hypothermia induced by a simple torso-cooling pad

“…These models were subsequently used to predict the temperatures in the brain and spinal cord during 30 min of mild and moderate hypothermia. If agreement can be obtained between the theoretical predictions and the acquired experimental data, then the previously developed theoretical study based on human anatomy [14,20] can present a reliable foundation for the development of a cooling pad that can achieve hypothermia in both the brain and spinal cord. The use of this pad would therefore provide neuroprotection against secondary injury as well as prevent permanent damage to neurological tissue following traumatic injury to the CNS.…”

“…Similar to previous models of the human head [11,14,18,31] and a previous model of a rat head [35], a 3D rat head model was developed as a hemispherical structure consisting of the brain tissue, CSF layer, bone, and scalp. A schematic diagram of the rat head model is shown in Fig.…”

“…Several theoretical models based on Pennes' bioheat equation have been developed to study cooling in brain tissue [10][11][12][13][14][15][16][17][18][19], whereas the only known theoretical model to study spinal cord hypothermia was developed by the present author in a previous study [20]. One-dimensional models of adult and infant heads were developed by Dexter and Hinderman [10] and used to study the effects of convection, metabolism, and conduction during cardiopulmonary bypass brain cooling.…”

“…Moreover, it was shown that the effectiveness of surface cooling was more evident in ischemic brain regions. The current author previously developed simplified 3D models of the human torso and head to predict the temperatures in the brain and spinal cord tissue and the surrounding CSF during therapeutic hypothermia using a cooling pad placed on the back of the torso [14,20]. The results of these studies showed a more than 2.5°C temperature reduction in the spinal cord and an approximately 1°C temperature reduction in the superficial layers of the brain tissue.…”

Design of a fuzzy logic controlled thermoelectric~brain hypothermia system

“…There are many applications related to selective cooling of biological tissues in the field of medicine [1][2][3][4][5][6][7][8]. A new and useful approach was developed by researchers at the University of Chicago for the treatment of patients after strokes and heart attacks based on cooling organs using specially developed ice slurry [3].…”