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An analysis of hypoxia in sheep brain using a mathematical model
M Sharan1, A S Popel, M L Hudak
1Centre for Atmospheric Sciences, Indian Institute of Technology, Delhi.
Annals of Biomedical Engineering
|June 4, 1999
Summary
Carbon monoxide (CO) hypoxia increases cerebral blood flow (CBF) more than hypoxic hypoxia due to lower tissue PO2. Blood viscosity, not tissue PO2, explains CBF changes in anemic hypoxia.
Area of Science:
- Physiology
- Biophysics
Background:
- Cerebral blood flow (CBF) increases during hypoxia to maintain oxygen delivery.
- Carbon monoxide (CO) hypoxia causes a greater CBF increase than hypoxic hypoxia, despite higher arterial PO2.
Purpose of the Study:
- To investigate if differences in tissue PO2 explain the greater CBF response to CO hypoxia compared to hypoxic hypoxia.
- To determine the role of tissue PO2 and blood viscosity in anemic hypoxia's effect on CBF.
Main Methods:
- Analysis of published data using a compartmental mathematical model.
- Modeling calculations to assess tissue PO2 and blood viscosity under different hypoxia conditions.
Main Results:
- Tissue PO2 was lower in CO hypoxia than hypoxic hypoxia due to increased oxyhemoglobin affinity.
- Changes in tissue PO2 predicted alterations in CBF.
- Blood viscosity changes, not tissue PO2, accounted for increased CBF in anemic hypoxia.
Conclusions:
- Lower tissue PO2, influenced by oxyhemoglobin affinity, drives the exaggerated CBF increase in CO hypoxia.
- Blood viscosity is the primary factor influencing CBF changes in anemic hypoxia.