Cerebral metabolic rate of oxygen

Definition: Cerebral metabolic rate of oxygen is the oxygen consumption of the brain determined by the difference of oxygen flowing into and out of a certain brain region. Together with the cerebral blood flow, it determines the level of blood oxygenation. There is a way to estimate cerebral metabolic rate of oxygen from cerebral blood flow, deoxygenated hemoglobin and oxygenated hemoglobin. If the arterial oxygen saturation is assumed to be 1, then the relative change in cerebral metabolic rate of oxygen is given by : $\left( 1 + \frac{\Delta CMRO_{2}}{CMRO_{2,0}}\right) = \frac{\left(1 + \frac{\Delta CBF}{CBF_{0}}\right)\left(1 + \gamma R\frac{\Delta HHb}{HHb_{0}}\right)}{\left(1 + \gamma T\frac{\Delta HbT}{HbT_{0}}\right)}$ where the sub index 0 represent baseline values and $\Delta( . . . )$ simply represent the variation of the respective parameter. Finally, $\gamma R$ and $\gamma T$ represent the correspondent factors which relate the fractional hemoglobin changes in the venous compartment to those across all vascular components. The parameters $\gamma R$ and $\gamma T$ can be calculated as: $\gamma R = \frac{\left(\frac{\Delta HHb_{v}}{HHb_{v,0}}\right)}{\left(\frac{\Delta HHb}{HHb_{0}}\right)}$ $\gamma T = \frac{\left(\frac{\Delta HbT_{v}}{HbT_{v,0}}\right)}{\left(\frac{\Delta HbT}{HbT_{0}}\right)}$ where: $\Delta HHb_{v}$ is the variation of deoxygenated hemoglobin concentration in the localized venous compartment. $HHb_{v,0}$ is the baseline deoxygenated hemoglobin concentration in the localized venous compartment. $\Delta HbT_{v}$ is the variation of total hemoglobin concentration in the localized venous compartment. $HbT_{v,0}$ is the baseline total hemoglobin concentration in the localized venous compartment.

Category: Neuroscience

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Abbreviation or symbol: CMRO2

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References: https://doi.org/10.1088/0031-9155/48/15/311

https://doi.org/10.1016/j.neuroimage.2012.01.040

https://doi.org/10.1016/j.neuroimage.2004.07.013

https://doi.org/10.1016/j.neuroimage.2023.120189

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