Starling forces drive intracranial water exchange during normal and pathological states.

Abstract

AIM:

To quantify the exchange of water between cerebral compartments, specifically blood, tissue, perivascular pathways, and cerebrospinal fluid-filled spaces, on the basis of experimental data and to propose a dynamic global model of water flux through the entire brain to elucidate functionally relevant fluid exchange phenomena.

METHODS:

The mechanistic computer model to predict brain water shifts is discretized by cerebral compartments into nodes. Water and species flux is calculated between these nodes across a network of arcs driven by Hagen-Poiseuille flow (blood), Darcy flow (interstitial fluid transport), and Starling's Law (transmembrane fluid exchange). Compartment compliance is accounted for using a pressure-volume relationship to enforce the Monro-Kellie doctrine. This nonlinear system of differential equations is solved implicitly using MATLAB software.

RESULTS:

The model predictions of intraventricular osmotic injection caused a pressure rise from 10 to 22 mmHg, followed by a taper to 14 mmHg over 100 minutes. The computational results are compared to experimental data with R2=0.929. Moreover, simulated osmotic therapy of systemic (blood) injection reduced intracranial pressure from 25 to 10 mmHg. The modeled volume and intracranial pressure changes following cerebral edema agree with experimental trends observed in animal models with R2=0.997.

CONCLUSION:

The model successfully predicted time course and the efficacy of osmotic therapy for clearing cerebral edema. Furthermore, the mathematical model implicated the perivascular pathways as a possible conduit for water and solute exchange. This was a first step to quantify fluid exchange throughout the brain.

• Authors: Andreas A Linninger, Colin Xu, Kevin Tangen, Grant Hartung
• Journal: Croatian medical journal (Croat Med J) Vol. 58 Issue 6 Pg. 384-394 (Dec 31 2017) ISSN: 1332-8166 [Electronic] Croatia
• PMID: 29308830 (Publication Type: Journal Article)

Topics

• Animals
• Biological Transport
• Body Water (physiology)
• Brain (metabolism)
• Brain Edema (metabolism)
• Cerebrovascular Circulation (physiology)
• Computer Simulation
• Humans
• Intracranial Pressure (physiology)