Annals of Biomedical Engineering

, Volume 37, Issue 11, pp 2288–2298 | Cite as

Effects of Autoregulation and CO2 Reactivity on Cerebral Oxygen Transport

Article

Abstract

Both autoregulation and CO2 reactivity are known to have significant effects on cerebral blood flow and thus on the transport of oxygen through the vasculature. In this paper, a previous model of the autoregulation of blood flow in the cerebral vasculature is expanded to include the dynamic behavior of oxygen transport through binding with hemoglobin. The model is used to predict the transfer functions for both oxyhemoglobin and deoxyhemoglobin in response to fluctuations in arterial blood pressure and arterial CO2 concentration. It is shown that only six additional nondimensional groups are required in addition to the five that were previously found to characterize the cerebral blood flow response. A resonant frequency in the pressure-oxyhemoglobin transfer function is found to occur in the region of 0.1 Hz, which is a frequency of considerable physiological interest. The model predictions are compared with results from the published literature of phase angle at this frequency, showing that the effects of changes in breathing rate can significantly alter the inferred phase dynamics between blood pressure and hemoglobin. The question of whether dynamic cerebral autoregulation is affected under conditions of stenosis or stroke is then examined.

Keywords

Autoregulation Cerebral blood flow CO2 Transfer function Mathematical model Stroke 

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Copyright information

© Biomedical Engineering Society 2009

Authors and Affiliations

  1. 1.Institute of Biomedical Engineering, Department of Engineering ScienceUniversity of OxfordOxfordUK
  2. 2.Photon Migration Imaging LaboratoryMassachusetts General HospitalCharlestownUSA

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