title: Assessment of non-invasive ICP during CSF infusion test: an approach with transcranial Doppler.
abstract: BACKGROUND
  This study aimed to compare four non-invasive intracranial pressure (nICP) methods in a prospective cohort of hydrocephalus patients whose cerebrospinal fluid dynamics was investigated using infusion tests involving controllable test-rise of ICP.
  
  
  METHODS
  Cerebral blood flow velocity (FV), ICP and non-invasive arterial blood pressure (ABP) were recorded in 53 patients diagnosed for hydrocephalus. Non-invasive ICP methods were based on: (1) interaction between FV and ABP using black-box model (nICP_BB); (2) diastolic FV (nICP_FVd); (3) critical closing pressure (nICP_CrCP); (4) transcranial Doppler-derived pulsatility index (nICP_PI). Correlation between rise in ICP (∆ICP) and ∆nICP and averaged correlations for changes in time between ICP and nICP during infusion test were investigated.
  
  
  RESULTS
  From baseline to plateau, all nICP estimators increased significantly. Correlations between ∆ICP and ∆nICP were better represented by nICP_PI and nICP_BB: 0.45 and 0.30 (p < 0.05). nICP_FVd and nICP_CrCP presented non-significant correlations: -0.17 (p = 0.21), 0.21 (p = 0.13). For changes in ICP during individual infusion test nICP_PI, nICP_BB and nICP_FVd presented similar correlations with ICP: 0.39 ± 0.40, 0.39 ± 0.43 and 0.35 ± 0.41 respectively. However, nICP_CrCP presented a weaker correlation (R = 0.29 ± 0.24).
  
  
  CONCLUSIONS
  Out of the four methods, nICP_PI was the one with best performance for predicting changes in ∆ICP during infusion test, followed by nICP_BB. Unreliable correlations were shown by nICP_FVd and nICP_CrCP. Changes of ICP observed during the test were expressed by nICP values with only moderate correlations.
authors.affiliation: Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Box 167, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, UK. dac69@cam.ac.uk.
authors.forename: D
authors.initials: D
authors.lastname: Cardim
authors.affiliation: Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Box 167, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, UK.|Institute of Electronic Systems, Warsaw University of Technology, Warsaw, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Czosnyka
authors.affiliation: Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Box 167, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, UK.
authors.forename: J
authors.initials: J
authors.lastname: Donnelly
authors.affiliation: Neurosciences Critical Care Unit, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
authors.forename: C
authors.initials: C
authors.lastname: Robba
authors.affiliation: Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Box 167, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, UK.
authors.forename: B C T
authors.initials: BC
authors.lastname: Cabella
authors.affiliation: Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Box 167, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, UK.
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.affiliation: Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Box 167, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, UK.
authors.forename: M T
authors.initials: MT
authors.lastname: Cabeleira
authors.affiliation: Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Box 167, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, UK.
authors.forename: P
authors.initials: P
authors.lastname: Smielewsky
authors.affiliation: Department of Neurology, University Hospital Aachen, Aachen, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Haubrich
authors.affiliation: Division of Neurosurgery, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
authors.forename: M R
authors.initials: MR
authors.lastname: Garnett
authors.affiliation: Division of Neurosurgery, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
authors.forename: J D
authors.initials: JD
authors.lastname: Pickard
authors.affiliation: Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Box 167, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, UK.
authors.forename: Z
authors.initials: Z
authors.lastname: Czosnyka
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000000981:diagnostic imaging*; D007427:Intracranial Pressure; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D017585:Ultrasonography, Doppler, Transcranial
keywords: CSF infusion test; Cerebral blood flow velocity; Non-invasive ICP monitoring; Transcranial Doppler