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 still 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/°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.