ASPIRE: Analysis of Cerebrospinal Fluid Using Rheology
Supported by: Department
Principal Investigator at BMC: James Holsapple, MD
Primary Research Contact: Brandon Finn, BA (617-638-8600)
Sixty percent of newly implanted hydrocephalus shunts fail in the first two years after implantation, a fact that significantly contributes to the mortality and morbidity of (primarily pediatric) hydrocephalus patients. One aspect of shunt flow that has received very little to no attention at all is the fluid dynamic properties of the cerebrospinal fluid (CSF). While the biochemical profile (ionic composition, cell counts) of CSF has been well documented in a variety of acute and chronic conditions, the same is not true for its fluid properties. CSF viscosity seems to increase at higher shear rates, which may indicate that CSF is a shear-thickening fluid. Additionally, most shunt manufacturers assume CSF shunt flow rates of less than 1 mL/min, and computational fluid dynamic simulations suggest that such flow rates correspond to a maximum shear rate of less than 200 s-1.
In addition to these uncertainties in CSF viscosity, its viscoelastic properties have so far been neglected completely. Different cellular and protein concentrations can significantly affect the viscoelastic properties of a fluid, and in the case of CSF may significantly affect the fluid dynamics through shunt catheters. Rotational rheometry at different frequencies and extensional rheometry on the same samples are required to fully characterize CSF fluid properties. The full fluid characterization of CSF therefore fills an important gap and could enable the development of surrogate fluids which would help in the experimental evaluation of candidate catheter designs.
Because our current understanding of the fluid properties of CSF is lacking, this study seeks to analyze the characteristics of CSF, which include dynamic viscosity, shear stress, and corresponding shear rate in order to better understand to what extent it exhibits Newtonian or non-Newtonian liquid characteristics. Results of this analysis have the potential to influence future catheter designs and may be useful in decreasing the incidence of blockages in hydrocephalus shunts.
In order to be eligible to participate in this study, an individual must meet all of the following criteria:
- Age ≥18 years
- Scheduled to receive a therapeutic large volume spinal tap/lumbar puncture in clinic as part of SOC or hospitalized in the ICU with an EVD whereby CSF removal is needed to relieve acute hydrocephalus condition
- Willing to provide 5cc of would-be discarded CSF
An individual who meets any of the following criteria will be excluded from participation in this study:
- Active infectious disease
Status: Actively enrolling patients