Medical & Biological Engineering & Computing

, Volume 48, Issue 11, pp 1123–1131 | Cite as

Real-time estimation of cerebrospinal fluid system parameters via oscillating pressure infusion

  • Kennet AnderssonEmail author
  • Ian R. Manchester
  • Jan Malm
  • Anders Eklund
Original Article


Hydrocephalus is related to a disturbed cerebrospinal fluid (CSF) system. For diagnosis, lumbar infusion test are performed to estimate outflow conductance, C out, and pressure volume index, PVI, of the CSF system. Infusion patterns and analysis methods used in current clinical practice are not optimized. Minimizing the investigation time with sufficient accuracy is of major clinical relevance. The aim of this study was to propose and experimentally evaluate a new method, the oscillating pressure infusion (OPI). The non-linear model of the CSF system was transformed into a linear time invariant system. Using an oscillating pressure pattern and linear system identification methods, C out and PVI with confidence intervals, were estimated in real-time. Forty-two OPI and constant pressure infusion (CPI) investigations were performed on an experimental CSF system, designed with PVI = 25.5 ml and variable C out. The ARX model robustly estimated C out (mean C out,OPI − C out,CPI = 0.08 μl/(s kPa), n = 42, P = 0.68). The Box–Jenkins model proved most reliable for PVI (23.7 ± 2.0 ml, n = 42). The OPI method, with its oscillating pressure pattern and new parameter estimation methods, efficiently estimated C out and PVI as well as their confidence intervals in real-time. The results from this experimental study show potential for the OPI method and supports further evaluation in a clinical setting.


Normal pressure hydrocephalus System identification Outflow resistance Outflow conductance Intracranial pressure Infusion test 



This project was funded by the Swedish research council, Vinnova, and the Foundation for Strategic Research through their joint initiative Biomedical Engineering for Better Health, and the Objective 2 Norra Norrland—EU Structural Fund.

Supplementary material

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Supplementary material 1 (DOC 79 kb)
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Supplementary material 2 (EPS 2272 kb)
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Supplementary material 3 (DOC 66 kb)


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Copyright information

© International Federation for Medical and Biological Engineering 2010

Authors and Affiliations

  • Kennet Andersson
    • 1
    • 2
    Email author
  • Ian R. Manchester
    • 3
    • 4
  • Jan Malm
    • 5
  • Anders Eklund
    • 1
    • 2
    • 6
  1. 1.Department of Radiation SciencesUmeå UniversityUmeåSweden
  2. 2.Department of Biomedical Engineering and InformaticsUmeå University HospitalUmeåSweden
  3. 3.Computer Science and Artificial Intelligence LaboratoryMassachusetts Institute of TechnologyCambridgeUSA
  4. 4.Department of Applied Physics and ElectronicsUmeå UniversityUmeåSweden
  5. 5.Department of Clinical NeuroscienceUmeå UniversityUmeåSweden
  6. 6.Centre of Biomedical Engineering and PhysicsUmeå UniversityUmeåSweden

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