title: Role of microvascular shunts in the loss of cerebral blood flow autoregulation.
abstract: Historically, determination of the critical cerebral perfusion pressure (CPP) was done in animals by a progressive lowering of arterial pressure yielding a nominal critical CPP of 60 mmHg. Subsequently, it was shown that if the CPP was decreased by increasing intracranial pressure (ICP), critical CPP fell to 30 mmHg. This discrepancy was unexplained. We recently provided evidence that the decrease in critical CPP was due to microvascular shunting resulting in maintained cerebral blood flow (CBF) at a lower CPP. We demonstrated by a progressive increase in ICP in rats using two-photon laser scanning microscopy (2PLSM) that the transition from capillary to microvascular shunt flow is a pathological process. We surmise that the loss of CBF autoregulation revealed by decreasing arterial pressure occurs by dilation of normal cerebral blood vessels whereas that which occurs by increasing ICP is due to microvascular shunting. Our observations indicate that the loss of CBF autoregulation we observed in brain injured patients that changes on an hourly or daily basis reflects an important pathophysiological process impacting on outcome that remains to be determined.
authors.affiliation: Department of Neurosurgery, University of New Mexico, 1101 Yale Blvd, NE, Domenici Hall, Brain Center, RM 1131B, Albuquerque, NM, 87131, USA. enemoto@salud.unm.edu.
authors.forename: Edwin M
authors.initials: EM
authors.lastname: Nemoto
authors.affiliation: Department of Neurosurgery, University of New Mexico, 1101 Yale Blvd, NE, Domenici Hall, Brain Center, RM 1131B, Albuquerque, NM, 87131, USA.|BRaIN Imaging Center, University of New Mexico, Albuquerque, NM, 87106, USA.
authors.forename: Denis E
authors.initials: DE
authors.lastname: Bragin
authors.affiliation: Department of Neurosurgery, University of New Mexico, 1101 Yale Blvd, NE, Domenici Hall, Brain Center, RM 1131B, Albuquerque, NM, 87131, USA.
authors.forename: Gloria
authors.initials: G
authors.lastname: Statom
authors.affiliation: Department of Neurosurgery, University of New Mexico, 1101 Yale Blvd, NE, Domenici Hall, Brain Center, RM 1131B, Albuquerque, NM, 87131, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Krasberg
authors.affiliation: Department of Neurosurgery, University of New Mexico, 1101 Yale Blvd, NE, Domenici Hall, Brain Center, RM 1131B, Albuquerque, NM, 87131, USA.
authors.forename: Suguna
authors.initials: S
authors.lastname: Pappu
authors.affiliation: Department of Neurosurgery, University of New Mexico, 1101 Yale Blvd, NE, Domenici Hall, Brain Center, RM 1131B, Albuquerque, NM, 87131, USA.
authors.forename: Bobby
authors.initials: B
authors.lastname: Sena
authors.affiliation: Department of Neurosurgery, University of New Mexico, 1101 Yale Blvd, NE, Domenici Hall, Brain Center, RM 1131B, Albuquerque, NM, 87131, USA.
authors.forename: Tracey
authors.initials: T
authors.lastname: Berlin
authors.affiliation: Department of Neurosurgery, University of New Mexico, 1101 Yale Blvd, NE, Domenici Hall, Brain Center, RM 1131B, Albuquerque, NM, 87131, USA.
authors.forename: Kim
authors.initials: K
authors.lastname: Olin
authors.affiliation: Department of Neurosurgery, University of New Mexico, 1101 Yale Blvd, NE, Domenici Hall, Brain Center, RM 1131B, Albuquerque, NM, 87131, USA.
authors.forename: Howard
authors.initials: H
authors.lastname: Yonas
mesh_terms: D002560:Cerebrovascular Circulation; D004562:Electrocardiography; D006706:Homeostasis; D006801:Humans; D018613:Microscopy, Confocal; D055806:Microvessels / Q000502:physiology*; D008991:Monitoring, Physiologic
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