The design of a digital cerebrovascular simulation model for teaching and research

We developed a comprehensive cerebral blood flow and intracranial pressure model to simulate and study the complex interactions in cerebrovascular dynamics caused by multiple simultaneous alterations, including normal and abnormal functional states of autoregulation of the brain.

Individual published equations (derived from prior animal and human studies) were implemented into a comprehensive simulation program. Included in the normal physiological modeling was cerebral blood flow, arterial blood pressure, and carbon dioxide (CO(2)) partial pressure. We also added external and pathological perturbations, such as head-up position and intracranial hemorrhage.

The model performed clinically realistically given inputs of published traumatized patients and cases encountered by clinicians. The pulsatile nature of the output graphics was easy for clinicians to interpret. The maneuvers simulated include changes of basic physiological inputs (e.g., arterial blood pressure, central venous pressure, CO(2) tension, head-up position, and respiratory effects on vascular pressures) as well as pathological inputs (e.g., acute intracranial bleeding, and obstruction of cerebrospinal outflow).

Based on the results, we believe the model would be useful to teach complex relationships of brain hemodynamics and study clinical research questions such as the optimal head-up position, the effects of intracranial hemorrhage on cerebral hemodynamics, as well as the best CO(2) concentration, to reach the optimal compromise between intracranial pressure and perfusion. With the ability to vary the model's complexity, we believe it would be useful for both beginners and advanced learners. The model could also be used by practicing clinicians to model individual patients (entering the effects of needed clinical manipulations and then running the model to test for optimal combinations of therapeutic maneuvers).