title: Cerebral hemodynamic responses to blood pressure manipulation in severely head-injured patients in the presence or absence of intracranial hypertension.
abstract: The management of cerebral perfusion pressure (CPP) remains a controversial issue in the critical care of severely head-injured patients. Recently, it has been proposed that the state of cerebrovascular autoregulation should determine individual CPP targets. To find optimal perfusion pressure, we pharmacologically manipulated CPP in a range of 51 mm Hg (median; 25th-75th percentile, 48-53 mm Hg) to 108 mm Hg (102-112 mm Hg) on Days 0, 1, and 2 after severe head injury in 13 patients and studied the effects on intracranial pressure (ICP), autoregulation capacity, and brain tissue partial pressure of oxygen. Autoregulation was expressed as a static rate of regulation for 5-mm Hg CPP intervals based on middle cerebral artery flow velocity. When ICP was normal (26 occasions), there were no major changes in the measured variables when CPP was altered from a baseline level of 78 mm Hg (74-83 mm Hg), indicating that the brain was within autoregulation limits. Conversely, when intracranial hypertension was present (11 occasions), CPP reduction to less than 77 mm Hg (73-82 mm Hg) further increased ICP, decreased the static rate of regulation, and decreased brain tissue partial pressure of oxygen, whereas a CPP increase improved these variables, indicating that the brain was operating at the lower limit of autoregulation. We conclude that daily trial manipulation of arterial blood pressure over a wide range can provide information that may be used to optimize CPP management.
authors.affiliation: *Division of Perioperative Care and Emergency Medicine, Departments of †Neurology and ‡Neurosurgery, and the §Julius Center for Health Sciences and Primary Care, University Medical Center, Utrecht, The Netherlands.
authors.forename: Olaf L
authors.initials: OL
authors.lastname: Cremer
authors.forename: Gert W
authors.initials: GW
authors.lastname: van Dijk
authors.forename: Gerrit J
authors.initials: GJ
authors.lastname: Amelink
authors.forename: Anne Marie G A
authors.initials: AMGA
authors.lastname: de Smet
authors.forename: Karel G M
authors.initials: KGM
authors.lastname: Moons
authors.forename: Cornelis J
authors.initials: CJ
authors.lastname: Kalkman
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D006259:Craniocerebral Trauma / Q000150:complications / Q000503:physiopathology* / Q000601:surgery*; D005260:Female; D015600:Glasgow Coma Scale; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D019586:Intracranial Hypertension / Q000209:etiology / Q000503:physiopathology* / Q000601:surgery*; D008297:Male; D020768:Middle Cerebral Artery / Q000502:physiology; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome