A Theoretical Model of Oxygen Delivery and Metabolism for Physiologic Interpretation of Quantitative Cerebral Blood Flow and Metabolic Rate of Oxygen

The coupling of cerebral blood flow (CBF) and metabolic rate of oxygen (CMRO2) during physiologic and pathophysiologic conditions remains the subject of debate. In the present study, we have developed a theoretical model for oxygen delivery and metabolism, which describes the diffusion of oxygen at...

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Bibliographic Details
Published in:Journal of cerebral blood flow and metabolism 2003-11, Vol.23 (11), p.1314-1323
Main Authors: Hayashi, Takuya, Watabe, Hiroshi, Kudomi, Nobuyuki, Kim, Kyeong Min, Enmi, Jun-Ichiro, Hayashida, Kohei, Iida, Hidehiro
Format: Article
Language:English
Subjects:
Biological and medical sciences
Biological Transport
Brain Ischemia
Capillaries
Cerebral circulation. Blood-brain barrier. Choroid plexus. Cerebrospinal fluid. Circumventricular organ. Meninges
Cerebrovascular Circulation - physiology
Computer Simulation
Diffusion
Female
Fundamental and applied biological sciences. Psychology
Hemoglobins - metabolism
Humans
Male
Models, Cardiovascular
Models, Theoretical
Oxygen - blood
Oxygen - metabolism
Regional Blood Flow - physiology
Vertebrates: nervous system and sense organs
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Summary:The coupling of cerebral blood flow (CBF) and metabolic rate of oxygen (CMRO2) during physiologic and pathophysiologic conditions remains the subject of debate. In the present study, we have developed a theoretical model for oxygen delivery and metabolism, which describes the diffusion of oxygen at the capillary-tissue interface and the nonlinear nature of hemoglobin (Hb) affinity to oxygen, allowing a variation in simple-capillary oxygen diffusibility, termed “effective oxygen diffusibility (EOD).” The model was used to simulate the relationship between CBF and CMRO2, as well as oxygen extraction fraction (OEF), when various pathophysiologic conditions were assumed involving functional activation, ischemia, hypoxia, anemia, or hypo- and hyper-capnic CBF variations. The simulations revealed that, to maintain CMRO2 constant, a variation in CBF and Hb required active change in EOD. In contrast, unless the EOD change took place, the brain allowed small but significant nonlinear change in CMRO2 directly dependent upon oxygen delivery. Application of the present model to quantitative neuroimaging of CBF and CMRO2 enables us to evaluate the biologic response at capillary level other than Hb- and flow-dependent properties of oxygen transport and may give us another insight regarding the physiologic control of oxygen delivery in the human brain.
ISSN:0271-678X
1559-7016
DOI:10.1097/01.WCB.0000090506.76664.00