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A computational model of cerebrospinal fluid production and reabsorption driven by Starling forces.

Buishas J, Gould IG, Linninger AA - Croat. Med. J. (2014)

Bottom Line: This model investigates the effect of osmotic pressure on water transport between the cerebral vasculature, the extracellular space (ECS), the perivascular space (PVS), and the CSF.Investigations into the effect of osmotic pressure on the volume of ventricles and the flux of ions in the blood, choroid plexus epithelium, and CSF are reviewed.Water flux from the ECS to the CSF is identified as a key feature of intracranial dynamics.

View Article: PubMed Central - PubMed

Affiliation: Andreas A. Linninger, Professor of Chemical Engineering and Bioengineering, University of Illinois at Chicago, Laboratory for Product and Process Design, M/C 063, 851 S. Morgan St. - 218 SEO, Chicago, Illinois 60607-7000, linninge@uic.edu.

ABSTRACT
Experimental evidence has cast doubt on the classical model of river-like cerebrospinal fluid (CSF) flow from the choroid plexus to the arachnoid granulations. We propose a novel model of water transport through the parenchyma from the microcirculation as driven by Starling forces. This model investigates the effect of osmotic pressure on water transport between the cerebral vasculature, the extracellular space (ECS), the perivascular space (PVS), and the CSF. A rigorous literature search was conducted focusing on experiments which alter the osmolarity of blood or ventricles and measure the rate of CSF production. Investigations into the effect of osmotic pressure on the volume of ventricles and the flux of ions in the blood, choroid plexus epithelium, and CSF are reviewed. Increasing the osmolarity of the serum via a bolus injection completely inhibits nascent fluid flow production in the ventricles. A continuous injection of a hyperosmolar solution into the ventricles can increase the volume of the ventricle by up to 125%. CSF production is altered by 0.231 μL per mOsm in the ventricle and by 0.835 μL per mOsm in the serum. Water flux from the ECS to the CSF is identified as a key feature of intracranial dynamics. A complete mathematical model with all equations and scenarios is fully described, as well as a guide to constructing a computational model of intracranial water balance dynamics. The model proposed in this article predicts the effects the osmolarity of ECS, blood, and CSF on water flux in the brain, establishing a link between osmotic imbalances and pathological conditions such as hydrocephalus and edema.

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Ventriculo-cisternal perfusion method for studying the physiology of cerebrospinal fluid (CSF) production. The lateral ventricle is continuously injected with artificial CSF containing a dye. Nascent fluid is defined as any fluid that is drawn into the ventricle as a result of osmotic pressure from the capillary bed throughout the extracellular space (ECS) and epithelium. The flow rate of nascent fluid into the ventricle is determined based on the dilution of the dye measured in the collection fluid from the cisterna magna. Qf is calculated using equation 1-2 where Qinj is the bulk flow rate of the perfusion fluid, Qout is the bulk flow rate of the collection fluid, QSAS is the bulk flow rate of the fluid in the SAS, Cinj is the tracer concentration in the perfusion fluid, and Cout is the tracer concentration in the collection fluid.
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Figure 3: Ventriculo-cisternal perfusion method for studying the physiology of cerebrospinal fluid (CSF) production. The lateral ventricle is continuously injected with artificial CSF containing a dye. Nascent fluid is defined as any fluid that is drawn into the ventricle as a result of osmotic pressure from the capillary bed throughout the extracellular space (ECS) and epithelium. The flow rate of nascent fluid into the ventricle is determined based on the dilution of the dye measured in the collection fluid from the cisterna magna. Qf is calculated using equation 1-2 where Qinj is the bulk flow rate of the perfusion fluid, Qout is the bulk flow rate of the collection fluid, QSAS is the bulk flow rate of the fluid in the SAS, Cinj is the tracer concentration in the perfusion fluid, and Cout is the tracer concentration in the collection fluid.

Mentions: Ventriculo-cisternal perfusion (VCP) measures the effect of osmolarity on the formation of CSF (Figure 3). An infusion pump injects a perfusion solution containing a tracer via an inflow cannula into the lateral ventricle. The osmolarity of the ventricle is altered by injecting an anisotonic solution into the ventricle, either via a continuous or bolus injection. Fluid is then collected from the outflow cannula inserted into the cisterna magna. This procedure allows for indirect measurement of the production rate of nascent fluid, the volumetric flux of water into the lateral ventricle from either the choroid plexus or through the ependymal layer from the ECS. The rate of nascent fluid formation is calculated using equation 1-2 where Qinj is the bulk flow rate of the perfusion fluid, Qout is the bulk flow rate of the collection fluid, QSAS is the bulk flow rate of the fluid in the SAS, Cinj is the tracer concentration in the perfusion fluid, and Cout is the tracer concentration in the collection fluid.


A computational model of cerebrospinal fluid production and reabsorption driven by Starling forces.

Buishas J, Gould IG, Linninger AA - Croat. Med. J. (2014)

Ventriculo-cisternal perfusion method for studying the physiology of cerebrospinal fluid (CSF) production. The lateral ventricle is continuously injected with artificial CSF containing a dye. Nascent fluid is defined as any fluid that is drawn into the ventricle as a result of osmotic pressure from the capillary bed throughout the extracellular space (ECS) and epithelium. The flow rate of nascent fluid into the ventricle is determined based on the dilution of the dye measured in the collection fluid from the cisterna magna. Qf is calculated using equation 1-2 where Qinj is the bulk flow rate of the perfusion fluid, Qout is the bulk flow rate of the collection fluid, QSAS is the bulk flow rate of the fluid in the SAS, Cinj is the tracer concentration in the perfusion fluid, and Cout is the tracer concentration in the collection fluid.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4228294&req=5

Figure 3: Ventriculo-cisternal perfusion method for studying the physiology of cerebrospinal fluid (CSF) production. The lateral ventricle is continuously injected with artificial CSF containing a dye. Nascent fluid is defined as any fluid that is drawn into the ventricle as a result of osmotic pressure from the capillary bed throughout the extracellular space (ECS) and epithelium. The flow rate of nascent fluid into the ventricle is determined based on the dilution of the dye measured in the collection fluid from the cisterna magna. Qf is calculated using equation 1-2 where Qinj is the bulk flow rate of the perfusion fluid, Qout is the bulk flow rate of the collection fluid, QSAS is the bulk flow rate of the fluid in the SAS, Cinj is the tracer concentration in the perfusion fluid, and Cout is the tracer concentration in the collection fluid.
Mentions: Ventriculo-cisternal perfusion (VCP) measures the effect of osmolarity on the formation of CSF (Figure 3). An infusion pump injects a perfusion solution containing a tracer via an inflow cannula into the lateral ventricle. The osmolarity of the ventricle is altered by injecting an anisotonic solution into the ventricle, either via a continuous or bolus injection. Fluid is then collected from the outflow cannula inserted into the cisterna magna. This procedure allows for indirect measurement of the production rate of nascent fluid, the volumetric flux of water into the lateral ventricle from either the choroid plexus or through the ependymal layer from the ECS. The rate of nascent fluid formation is calculated using equation 1-2 where Qinj is the bulk flow rate of the perfusion fluid, Qout is the bulk flow rate of the collection fluid, QSAS is the bulk flow rate of the fluid in the SAS, Cinj is the tracer concentration in the perfusion fluid, and Cout is the tracer concentration in the collection fluid.

Bottom Line: This model investigates the effect of osmotic pressure on water transport between the cerebral vasculature, the extracellular space (ECS), the perivascular space (PVS), and the CSF.Investigations into the effect of osmotic pressure on the volume of ventricles and the flux of ions in the blood, choroid plexus epithelium, and CSF are reviewed.Water flux from the ECS to the CSF is identified as a key feature of intracranial dynamics.

View Article: PubMed Central - PubMed

Affiliation: Andreas A. Linninger, Professor of Chemical Engineering and Bioengineering, University of Illinois at Chicago, Laboratory for Product and Process Design, M/C 063, 851 S. Morgan St. - 218 SEO, Chicago, Illinois 60607-7000, linninge@uic.edu.

ABSTRACT
Experimental evidence has cast doubt on the classical model of river-like cerebrospinal fluid (CSF) flow from the choroid plexus to the arachnoid granulations. We propose a novel model of water transport through the parenchyma from the microcirculation as driven by Starling forces. This model investigates the effect of osmotic pressure on water transport between the cerebral vasculature, the extracellular space (ECS), the perivascular space (PVS), and the CSF. A rigorous literature search was conducted focusing on experiments which alter the osmolarity of blood or ventricles and measure the rate of CSF production. Investigations into the effect of osmotic pressure on the volume of ventricles and the flux of ions in the blood, choroid plexus epithelium, and CSF are reviewed. Increasing the osmolarity of the serum via a bolus injection completely inhibits nascent fluid flow production in the ventricles. A continuous injection of a hyperosmolar solution into the ventricles can increase the volume of the ventricle by up to 125%. CSF production is altered by 0.231 μL per mOsm in the ventricle and by 0.835 μL per mOsm in the serum. Water flux from the ECS to the CSF is identified as a key feature of intracranial dynamics. A complete mathematical model with all equations and scenarios is fully described, as well as a guide to constructing a computational model of intracranial water balance dynamics. The model proposed in this article predicts the effects the osmolarity of ECS, blood, and CSF on water flux in the brain, establishing a link between osmotic imbalances and pathological conditions such as hydrocephalus and edema.

Show MeSH
Related in: MedlinePlus