title: Modelling cerebrovascular reactivity: a novel near-infrared biomarker of cerebral autoregulation?
abstract: Understanding changes in cerebral oxygenation, haemodynamics and metabolism holds the key to individualised, optimised therapy after acute brain injury. Near-infrared spectroscopy (NIRS) offers the potential for non-invasive, continuous bedside measurement of surrogates for these processes. Interest has grown in applying this technique to interpret cerebrovascular pressure reactivity (CVPR), a surrogate of the brain's ability to autoregulate blood flow. We describe a physiological model-based approach to NIRS interpretation which predicts autoregulatory efficiency from a model parameter k_aut. Data from three critically brain-injured patients exhibiting a change in CVPR were investigated. An optimal value for k_aut was determined to minimise the difference between measured and simulated outputs. Optimal values for k_aut appropriately tracked changes in CVPR under most circumstances. Further development of this technique could be used to track CVPR providing targets for individualised management of patients with altered vascular reactivity, minimising secondary neurological insults.
authors.affiliation: Neurocritical Care, University College Hospitals, Queen Square, London, UK. dave@davidhighton.net.|National Hospital for Neurology and Neurosurgery, Flat 40 Salisbury Mansions, St Anns Road, London, N153TP, UK. dave@davidhighton.net.
authors.forename: David
authors.initials: D
authors.lastname: Highton
authors.affiliation: Medical Physics and Bioengineering, University College London, Malet Place, London, UK.
authors.forename: Jasmina
authors.initials: J
authors.lastname: Panovska-Griffiths
authors.affiliation: Neurocritical Care, University College Hospitals, Queen Square, London, UK.|Institute of Neurology, University College London, Queen Square, London, UK.
authors.forename: Arnab
authors.initials: A
authors.lastname: Ghosh
authors.affiliation: Medical Physics and Bioengineering, University College London, Malet Place, London, UK.
authors.forename: Ilias
authors.initials: I
authors.lastname: Tachtsidis
authors.affiliation: Department of Mathematics, University of Portsmouth, Portsmouth, UK.
authors.forename: Murad
authors.initials: M
authors.lastname: Banaji
authors.affiliation: Medical Physics and Bioengineering, University College London, Malet Place, London, UK.
authors.forename: Clare
authors.initials: C
authors.lastname: Elwell
authors.affiliation: Neurocritical Care, University College Hospitals, Queen Square, London, UK.|Medical Physics and Bioengineering, University College London, Malet Place, London, UK.
authors.forename: Martin
authors.initials: M
authors.lastname: Smith
mesh_terms: D015415:Biomarkers / Q000032:analysis*; D001921:Brain / Q000098:blood supply* / Q000503:physiopathology; D001930:Brain Injuries / Q000175:diagnosis*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D006439:Hemodynamics; D006706:Homeostasis; D006801:Humans; D008991:Monitoring, Physiologic; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
chemical_list: D015415:Biomarkers; D010100:Oxygen