Modeling of intracranial pressure-temperature dynamics and its application to brain hypothermia treatment

Brain hypothermia treatment (BHT) is efficient in decompressing the intracranial hypertension in neurosurgery. However, BHT is stil I difficult and ineffective since quantitative relationship between decompression and brain hypothermia is unclear. The aim of this paper is to develop a theoretical model integrating the hemodynamics and the thermodynamics to quantitatively predict transient responses of the elevated intracranial pressure (ICP) to ambient cooling. The model consists of a lumped-parameter compartmental representation of the body and is based on two temperature-dependence mechanisms of metabolism and vascular water filtration. The model is verified by comparing the simulation results to population-averaged data and clinical evidences of BHT. The hypothermic decompression is linearly approximated by a transfer function comprising a gain of about 4.9 mmHg/degrees C, a dead time of about 1.0 h and a time constant of about 9.8 h. Using these quantitative data, a feedback control of elevated ICP is implemented in a simulated intracranial hypertension of vasogenic brain edema. Simulation results suggest the possibility of automatic control of the elevated ICP in BHT.