Oxygen delivery from the cerebral microvasculature to tissue is governed by a single time constant of approximately 6?seconds
Journal
Microcirculation
Journal Volume
25
Journal Issue
2
Date Issued
2018
Author(s)
Abstract
Objective: The cerebral microvasculature plays a key role in the coupling between cerebral blood flow and metabolism. Although experimental imaging techniques now allow for finely detailed measurements of flow and oxygenation, within humans measurements remain confined to a voxel-level scale, of order 1 mm. Mathematical models are thus key in interpreting such data. However, these can be highly complicated, due to the large number of vessels and the nonlinearities in the governing equations. Methods: We thus propose here a new model of the cerebral microvasculature and show how its behavior can be simplified based on the order of magnitude arguments. Results: The resulting model shows a dependence upon just two time constants, termed “slow” and “metabolic” time constants; the tissue oxygenation response can be characterized by convolution of the difference between the fractional flow and metabolic responses with a single exponential, with time constant equal to half the ratio of tissue volume to blood flow multiplied by the ratio of effective oxygen solubility in tissue and blood. Conclusions: The overall response time for the whole network is approximately 6 seconds; this value indicates that the flow response to increases in metabolic activity cannot be driven solely by changes in tissue oxygenation. ? 2017 John Wiley & Sons Ltd
Subjects
oxygen
Article
brain blood flow
brain blood vessel
mathematical model
metabolism
oxygen transport
priority journal
tissue oxygenation
viscosity
biological model
brain
brain circulation
human
microvasculature
oxygen consumption
physiology
time factor
vascularization
Brain
Cerebrovascular Circulation
Humans
Microvessels
Models, Biological
Oxygen
Oxygen Consumption
Time Factors
Type
journal article