title: A physical framework for implementing virtual models of intracranial pressure and cerebrospinal fluid dynamics in hydrocephalus shunt testing.
abstract: OBJECTIVE The surgical placement of a shunt designed to resolve the brain's impaired ability to drain excess CSF is one of the most common treatments for hydrocephalus. The use of a dynamic testing platform is an important part of shunt testing that can faithfully reproduce the physiological environment of the implanted shunts. METHODS A simulation-based framework that serves as a proof of concept for enabling the application of virtual intracranial pressure (ICP) and CSF models to a physical shunt-testing system was engineered. This was achieved by designing hardware and software that enabled the application of dynamic model-driven inlet and outlet pressures to a shunt and the subsequent measurement of the resulting drainage rate. RESULTS A set of common physiological scenarios was simulated, including oscillations in ICP due to respiratory and cardiac cycles, changes in baseline ICP due to changes in patient posture, and transient ICP spikes caused by activities such as exercise, coughing, sneezing, and the Valsalva maneuver. The behavior of the Strata valve under a few of these physiological conditions is also demonstrated. CONCLUSIONS Testing shunts with dynamic ICP and CSF simulations can facilitate the optimization of shunts to be more failure resistant and better suited to patient physiology.
authors.affiliation: Department of Bioengineering, University of Washington, Seattle; and.
authors.forename: Pranav
authors.initials: P
authors.lastname: Venkataraman
authors.affiliation: Division of Pediatric Neurosurgery, Seattle Children's Hospital, Seattle, Washington.
authors.forename: Samuel R
authors.initials: SR
authors.lastname: Browd
authors.affiliation: Department of Bioengineering, University of Washington, Seattle; and.
authors.forename: Barry R
authors.initials: BR
authors.lastname: Lutz
mesh_terms: D002555:Cerebrospinal Fluid / Q000502:physiology; D002557:Cerebrospinal Fluid Shunts / Q000295:instrumentation* / Q000379:methods; D003198:Computer Simulation; D003201:Computers; D003371:Cough / Q000503:physiopathology; D004867:Equipment Design / Q000295:instrumentation / Q000379:methods*; D015444:Exercise; D006439:Hemodynamics; D006801:Humans; D006849:Hydrocephalus / Q000503:physiopathology / Q000601:surgery*; D057446:Hydrodynamics; D007427:Intracranial Pressure; D008959:Models, Neurological; D010507:Periodicity; D011187:Posture; D012119:Respiration; D012912:Sneezing / Q000502:physiology; D012984:Software; D014636:Valsalva Maneuver / Q000502:physiology
keywords: CSF = cerebrospinal fluid; FOM = figure of merit; IAP = intraabdominal pressures; ICP = intracranial pressure; hydrocephalus; intracranial pressure; shunt; simulation system; ΔICV(t) = change in intracranial volume