title: The Correlation Between Intracranial Pressure and Cerebral Blood Flow Velocity During ICP Plateau Waves.
abstract: We previously showed that the flow-ICP index (Fix), a moving correlation coefficient between intracranial pressure (ICP) and cerebral blood flow velocity (CBFV), had marginally greater prognostic value for patients with traumatic brain injury (TBI) than an index of cerebral autoregulation (mean index, Mx). The aim of this study was to further examine the clinical and physiological relevance of Fix by studying its behaviour during ICP plateau waves in patients with TBI. Twenty-nine recordings of CBFV made during ICP plateau waves were analysed. Both Mx and Fix at baseline and peak ICP were significantly different, although the magnitude of Fix change was slightly greater. The correlation between Fix and cerebral perfusion pressure (CPP) was stronger than that between Mx and CPP. Unlike in our previous study, plotting Fix against CPP revealed a peak value in the range of "optimal" CPP, as indicated by the Mx versus CPP plot. The findings suggest that during periods of reduced CPP caused by plateau waves, the dynamic behaviour of Fix is similar to that of a measure of cerebral autoregulation. This conclusion needs to be verified against similar results obtained during episodes of supranormal CPP.
authors.affiliation: Department of Neurosurgery, Alfred Hospital, 1st Floor, Old Baker Building, Commercial Road, Melbourne, VIC, 3003, Australia. p.lewis@alfred.org.au.|Department of Surgery, Monash University, Melbourne, VIC, Australia. p.lewis@alfred.org.au.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Lewis
authors.affiliation: Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Smielewski
authors.affiliation: Department of Neurosurgery, Alfred Hospital, 1st Floor, Old Baker Building, Commercial Road, Melbourne, VIC, 3003, Australia.|Department of Surgery, Monash University, Melbourne, VIC, Australia.
authors.forename: Jeffrey V
authors.initials: JV
authors.lastname: Rosenfeld
authors.affiliation: Department of Neurosurgery, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK.
authors.forename: John D
authors.initials: JD
authors.lastname: Pickard
authors.affiliation: Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.
authors.forename: Marek
authors.initials: M
authors.lastname: Czosnyka
mesh_terms: D062186:Arterial Pressure; D001783:Blood Flow Velocity / Q000502:physiology*; D000070642:Brain Injuries, Traumatic / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D006706:Homeostasis; D006801:Humans; D019586:Intracranial Hypertension / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D007427:Intracranial Pressure / Q000502:physiology*; D017585:Ultrasonography, Doppler, Transcranial
keywords: Cerebral autoregulation; Cerebral blood flow velocity; Intracranial pressure; Traumatic brain injury