Assessment of cerebrovascular resistance with a model of cerebrovascular pressure transmission.

A method to assess continuous changes of cerebrovascular resistance based on a biomechanical model of cerebrovascular pressure transmission is developed. Such a method provides an end-point measure to assess new and/or existing management strategies during intensive-care management of patients with brain injury. Changes of both pial arteriolar resistance and cerebrovascular resistance derived by a physiologically based biomechanical model of cerebrovascular pressure transmission, the dynamic relationship between arterial blood pressure (ABP) and intracranial pressure (ICP), were compared to test the validity of the modeling procedure. Pressor challenge was administered to normoxic (N=5) and hypoxic (N=5) piglets equipped with closed cranial windows. Pial arteriolar diameters were used to compute arteriolar resistance. Percent change of pial arteriolar resistance (%DeltaPAR) and percent change of model-derived cerebrovascular resistance (%DeltasCVR) in response to pressor challenge were computed. During intact cerebrovascular regulation and during hypoxia-induced impairment of cerebrovascular regulation, changes in pial arteriolar resistance were accurately predicted by the proposed modeling method designed to assess changes of cerebrovascular resistance.