title: Volume measurement of cerebral blood flow: assessment of cerebral circulatory arrest.
abstract: BACKGROUND
  Cerebral blood flow (CBF) volume can be measured at bedside by color duplex flowmetry of the extracranial cerebral arteries. In neurointensive care patients, we prospectively tested the hypothesis that a CBF volume <100 ml/min indicates imminent cerebral circulatory arrest.
  
  
  METHODS
  CBF volume was determined as sum of flow volumes in the internal carotid and vertebral arteries of both sides. In 192 neurointensive care patients, 829 measurements were taken. When CBF volume fell short of 100 ml/min, common carotid and external carotid artery flow volumes were also measured, and transcranial color-coded duplex sonography (TCCD) of basal cerebral arteries was performed. Results were compared with actual clinical conditions, outcome, and previously published reference data.
  
  
  RESULTS
  All 41 patients with CBF volume <100 ml/min (range, 0-89 ml/min) were officially declared brain dead 2-126 hours after the measurement (median, 23 hours). TCCD revealed signs of cerebral circulatory arrest in all patients with a patent acoustic bone window. External carotid artery flow volumes were normal. The lowest CBF volume rate recorded in a surviving patient was 208 ml/min.
  
  
  CONCLUSIONS
  Early confirmation of cerebral circulatory arrest is of decisive importance if the patient is a potential organ donor. CBF volume measurement allows confirming the arrest of cerebral circulation even in patients without a patent acoustic bone window for TCCD. Because the critical lower threshold for survival appears to lie at 200 ml/min, bedside monitoring of CBF volume in neurointensive care patients may indicate a therapeutic window before irreversible circulatory arrest occurs.
authors.affiliation: Department of Child Neurology, Children's Hospital of the University of Tübingen, Tübingen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Schöning
authors.forename: Peter
authors.initials: P
authors.lastname: Scheel
authors.forename: Martin
authors.initials: M
authors.lastname: Holzer
authors.forename: Reinhold
authors.initials: R
authors.lastname: Fretschner
authors.forename: Bernd E
authors.initials: BE
authors.lastname: Will
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001776:Blood Circulation Time; D001783:Blood Flow Velocity; D001810:Blood Volume; D001921:Brain / Q000473:pathology; D001926:Brain Death; D002339:Carotid Arteries / Q000473:pathology; D002536:Cerebral Arteries / Q000473:pathology*; D002560:Cerebrovascular Circulation; D005260:Female; D006323:Heart Arrest; D006801:Humans; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow; D012212:Rheology; D013997:Time Factors; D014465:Ultrasonics; D018615:Ultrasonography, Doppler, Color; D018616:Ultrasonography, Doppler, Duplex