title: Non-invasive assessment of cerebral perfusion pressure in brain injured patients with moderate intracranial hypertension.
abstract: BACKGROUND
  A non-invasive estimation of cerebral perfusion pressure (CPP) using transcranial Doppler sonography was assessed in brain-injured patients by comparing conventional measurements of CPP (difference between mean arterial pressure and intracranial pressure) (CPPm) with the difference between AP(mean) and the critical closing pressure of the cerebral circulation (CPPe).
  
  
  METHODS
  Twenty adults with bilateral and diffuse brain injuries were included in the study. CPPe was estimated using a formula combining the phasic values of flow velocities and arterial pressure. In group A (n=10) the comparison was repeatedly performed under stable conditions. In group B (n=10) the comparison was performed during a CO(2) reactivity test. Covariance analysis was used to assess the relationships.
  
  
  RESULTS
  In group A, CPPe and CPPm were correlated (slope, 0.76; intercept, +10.9; 95% CI, -3.5 to +25.4). During the increase in intracranial pressure (group B) (+1.9 (sd 1.5) mm Hg per mm Hg of Pe'(co(2))) the relationship persisted (slope, 0.55; intercept, +32.6; 95% CI, +16.3 to +48.9) but the discrepancy between the two variables increased as reflected by the increase in bias and variability.
  
  
  CONCLUSIONS
  Non-invasive estimation of CPP can be used for brain monitoring of head-injured patients, but the accuracy of the method may depend on the level of intracranial hypertension.
authors.affiliation: Service d'Anesthésie-Réanimation et Unité Propre de Recherche de l'Enseignement Supérieur-Equipe d'Accueil (UPRES-EA 3540), Hôpital de Bicêtre, 94275 Le Kremlin Bicêtre, France. alain.edouard@bct.ap-hop-paris.fr
authors.forename: A R
authors.initials: AR
authors.lastname: Edouard
authors.forename: E
authors.initials: E
authors.lastname: Vanhille
authors.forename: S
authors.initials: S
authors.lastname: Le Moigno
authors.forename: D
authors.initials: D
authors.lastname: Benhamou
authors.forename: J-X
authors.initials: JX
authors.lastname: Mazoit
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D001794:Blood Pressure; D001930:Brain Injuries / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002245:Carbon Dioxide / Q000097:blood; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D015601:Injury Severity Score; D019586:Intracranial Hypertension / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D007427:Intracranial Pressure; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D008991:Monitoring, Physiologic / Q000379:methods; D010313:Partial Pressure; D011446:Prospective Studies; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*
chemical_list: D002245:Carbon Dioxide