title: Patient Specific Hardware-in-the-Loop Testing of Cerebrospinal Fluid Shunt Systems.
abstract: OBJECTIVE
  The development of increasingly sophisticated cerebrospinal fluid (CSF) shunts calls for test beds that can reproduce an ever larger range of physiologic and pathophysiologic behaviors. In particular, upcoming smart and active devices will require extensive testing under complex dynamic conditions. Herein, we describe a test bed that allows for fast, cost effective, and realistic in vitro testing of active and passive, gravitational and nongravitational CSF shunts based on the hardware-in-the-loop principle.
  
  
  METHODS
  The shunt to be tested is placed in a dynamic in vitro setup that interfaces with a mathematical model of the patient's relevant physiology, which is evaluated numerically in real time. The model parameters can be identified using standard clinical tests. The test bed accounts for posture-dependent behavior and viscoelastic effects.
  
  
  RESULTS
  Simulations of infusion tests, of intracranial pressure modulation by cardiovascular action, and of the effects of postural changes show good agreement with published results. Evaluation of valves without and with gravitational units show in modeled sitting patients the expected behavior of overdrainage and avoidance thereof, respectively. Finally, a 24-h test cycle based on recorded patient data elucidates the interaction between patient and shunt system expressed by drainage rate and intracranial pressure during typical daily activities.
  
  
  CONCLUSIONS
  We envision this test bed as a tool to quantify a shunt's performance within a realistic yet reproducible testing environment.
  
  
  CONCLUSIONS
  The test bed can improve our understanding of the complex interaction between patient and shunt system and may catalyze the development of active shunts, while reducing the number of necessary in vivo experiments.
authors.forename: Manuel
authors.initials: M
authors.lastname: Gehlen
authors.forename: Vartan
authors.initials: V
authors.lastname: Kurtcuoglu
authors.forename: Marianne Schmid
authors.initials: MS
authors.lastname: Daners
mesh_terms: D002557:Cerebrospinal Fluid Shunts; D003198:Computer Simulation; D004867:Equipment Design; D006801:Humans; D006849:Hydrocephalus / Q000503:physiopathology* / Q000601:surgery; D007427:Intracranial Pressure / Q000502:physiology*; D011187:Posture / Q000502:physiology*