title: Derangement of Cerebral Blood Flow Autoregulation During Intracranial Pressure Plateau Waves as Detected by Time and Frequency-Based Methods.
abstract: Plateau waves are sudden elevations of intracranial pressure (ICP) above 40 mmHg, lasting at least 5 min, and are associated with cerebral vasodilatation. We studied the performance of several parameters for cerebral autoregulation assessment during 30 plateau waves of 24 patients with traumatic brain injury. Continuous signals were collected for ICP, arterial blood pressure (ABP) and transcranial Doppler flow velocity (FV). Parameters both in the time domain (autoregulation index, ARI and mean flow index, Mx) and the frequency domain (transfer function gain, phase and coherence) were analysed. The role of different inputs, using either ABP or cerebral perfusion pressure (CPP) as input, was also tested.Autoregulation deteriorated from baseline to plateau, which could be demonstrated by a significant decrease in both ARI between ABP and FV (p = 0.013) and ARI between CPP and FV (p = 0.014). There was also a significant increase in Mx between CPP and FV (p = 0.004), but not in Mx between ABP and FV (p = 0.472). From the baseline to plateau, there was a significant increase in coherence between the ABP and FV at the very low frequency (p = 0.004). The transfer function phase and gain, on the other hand, revealed inconsistent performance.
authors.affiliation: Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK. xl334@cam.ac.uk.
authors.forename: Xiuyun
authors.initials: X
authors.lastname: Liu
authors.affiliation: Division of Neurosurgery , Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.
authors.forename: Marek
authors.initials: M
authors.lastname: Czosnyka
authors.affiliation: Division of Neurosurgery, Department of Clinical Neurosciences, 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, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK.
authors.forename: Georgios V
authors.initials: GV
authors.lastname: Varsos
authors.affiliation: Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Nasr
authors.affiliation: Division of Neurosurgery , Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Smielewski
mesh_terms: D062186:Arterial Pressure; D001783:Blood Flow Velocity; D000070642:Brain Injuries, Traumatic / Q000150:complications / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D019586:Intracranial Hypertension / Q000209:etiology / Q000503:physiopathology*; D007427:Intracranial Pressure; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D017585:Ultrasonography, Doppler, Transcranial
keywords: Autoregulation index; Blood pressure; Intracranial pressure; Mean flow index; Plateau waves; Transfer function