title: Optical bedside monitoring of cerebral blood flow in acute ischemic stroke patients during head-of-bed manipulation.
abstract: OBJECTIVE
  A primary goal of acute ischemic stroke (AIS) management is to maximize perfusion in the affected region and surrounding ischemic penumbra. However, interventions to maximize perfusion, such as flat head-of-bed (HOB) positioning, are currently prescribed empirically. Bedside monitoring of cerebral blood flow (CBF) allows the effects of interventions such as flat HOB to be monitored and may ultimately be used to guide clinical management.
  
  
  METHODS
  Cerebral perfusion was measured during HOB manipulations in 17 patients with unilateral AIS affecting large cortical territories in the anterior circulation. Simultaneous measurements of frontal CBF and arterial flow velocity were performed with diffuse correlation spectroscopy and transcranial Doppler ultrasound, respectively. Results were analyzed in the context of available clinical data and a previous study.
  
  
  RESULTS
  Frontal CBF, averaged over the patient cohort, decreased by 17% (P=0.034) and 15% (P=0.011) in the ipsilesional and contralesional hemispheres, respectively, when HOB was changed from flat to 30°. Significant (cohort-averaged) changes in blood velocity were not observed. Individually, varying responses to HOB manipulation were observed, including paradoxical increases in CBF with increasing HOB angle. Clinical features, stroke volume, and distance to the optical probe could not explain this paradoxical response.
  
  
  CONCLUSIONS
  A lower HOB angle results in an increase in cortical CBF without a significant change in arterial flow velocity in AIS, but there is variability across patients in this response. Bedside CBF monitoring with diffuse correlation spectroscopy provides a potential means to individualize interventions designed to optimize CBF in AIS.
authors.affiliation: From the Departments of Neurology (C.G.F., M.M., X.L., S.E.K., J.H.G., J.A.D.), Physics and Astronomy (R.C.M., M.N.K., D.L.M., A.G.Y.), and Radiology (J.A.D.), University of Pennsylvania, Philadelphia, PA; Institute of Physics, University of Campinas, Campinas, Brazil (R.C.M.); and ICFO-Institut de Ciències Fotòniques, Castelldefels, Barcelona, Spain (T.D.).
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Favilla
authors.forename: Rickson C
authors.initials: RC
authors.lastname: Mesquita
authors.forename: Michael
authors.initials: M
authors.lastname: Mullen
authors.forename: Turgut
authors.initials: T
authors.lastname: Durduran
authors.forename: Xiangping
authors.initials: X
authors.lastname: Lu
authors.forename: Meeri N
authors.initials: MN
authors.lastname: Kim
authors.forename: David L
authors.initials: DL
authors.lastname: Minkoff
authors.forename: Scott E
authors.initials: SE
authors.lastname: Kasner
authors.forename: Joel H
authors.initials: JH
authors.lastname: Greenberg
authors.forename: Arjun G
authors.initials: AG
authors.lastname: Yodh
authors.forename: John A
authors.initials: JA
authors.lastname: Detre
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology; D001921:Brain / Q000098:blood supply* / Q000503:physiopathology; D002545:Brain Ischemia / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002985:Clinical Protocols; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D020521:Stroke / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D016683:Supine Position / Q000502:physiology
keywords: perfusion; spectroscopy, near-infrared; stroke