Development and validation of an integrated computational model of cerebral blood flow and oxygenation

BACKGROUND: Various groups have constructed simulations and models of cerebral blood flow and oxygenation, each with its strengths and weaknesses. We describe the development and validation of a novel computational model, the Nottingham cerebral simulator (NCS), designed for experimental and teaching use. METHODS: Physiological hypotheses were converted into differential equations; these are solved numerically with respect to time. A battery of tests was derived from published literature against which to test the simulation: static and dynamic autoregulation responses; carbon dioxide reactivity; brain tissue oxygenation. The NCS was programmed to simulate the methodologies of published experiments and the results of the simulation and the published data were compared. RESULTS: The NCS results are qualitatively and quantitatively similar to published data. The values for regulatory indices were (published values in parentheses): index of autoregulation 0.9 (0.9); transient hyperemic response ratio 1.3 (1.3), carbon dioxide reactivity 2.4%-4.7% mm Hg-1 (2-4.5); brain tissue oxygen tension 22 mm Hg (20-100). CONCLUSIONS: The NCS is a credible model of cerebral blood flow and oxygenation, which warrants further use as an experimental and teaching tool.