title: Regional cerebral blood flow and cellular environment in subarachnoid hemorrhage: A thermal doppler flowmetry and microdialysis study.
abstract: BACKGROUND
  Cerebral microdialysis enables assessment of regional metabolic physiology and provides biomarkers for clinical correlation in critical conditions, such as subarachnoid hemorrhage (SAH). The aim of our current study was to investigate the correlation between regional cerebral blood flow and microdialysis parameters (glucose, lactate, glycerol, pyruvate concentrations, and lactate/pyruvate metabolic ratio) in patients with SAH.
  
  
  METHODS
  Twenty-one patients with SAH were enrolled in our retrospective study. Cerebral blood flow (CBF) based on thermal diffusion methodology, the thermal coefficient K, and microdialysis biochemical markers were recorded. The duration of the brain monitoring was 10 days.
  
  
  RESULTS
  Microdialysis glucose concentration was inversely related to the cerebral temperature and to the L/P ratio. Furthermore, it was positively correlated to all other microdialysis parameters but glycerol. The K coefficient was strongly and positively correlated with the temperature and marginally with the CBF. The L/P ratio was positively correlated with glycerol, while it was inversely correlated with the CBF. Patients who died had elevated L/P ratio and K coefficient compared to the survivors in our series.
  
  
  CONCLUSIONS
  Thermal conductivity coefficient may change over time as cerebral injury progresses and tissue properties alter. These alterations were found to be associated with the microdialysis metabolite concentrations and the CBF itself. The microdialysis biochemical indices of cell stress and death (glycerol, L/P ratio) were positively related to each other, while the measured L/P metabolic ratio was higher among patients who died.
authors.affiliation: Intensive Care Unit, General Hospital of Larisa, Greece. Electronic address: dcpapadopoulosmd@gmail.com.
authors.forename: D
authors.initials: D
authors.lastname: Papadopoulos
authors.affiliation: Department of Neurosurgery, Boston University, USA.
authors.forename: A
authors.initials: A
authors.lastname: Filippidis
authors.affiliation: Intensive Care Unit, General Hospital of Larisa, Greece.
authors.forename: G
authors.initials: G
authors.lastname: Krommidas
authors.affiliation: Department of Anesthesiology, University Hospital of Larisa, Greece.
authors.forename: G
authors.initials: G
authors.lastname: Vretzakis
authors.affiliation: Department of Neurosurgery, University Hospital of Larisa, Greece.
authors.forename: K
authors.initials: K
authors.lastname: Paterakis
authors.affiliation: Intensive Care Unit, General Hospital of Larisa, Greece.
authors.forename: A
authors.initials: A
authors.lastname: Komnos
authors.affiliation: Department of Neurosurgery, University Hospital of Larisa, Greece.
authors.forename: K N
authors.initials: KN
authors.lastname: Fountas
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D017078:Laser-Doppler Flowmetry / Q000379:methods*; D008297:Male; D017551:Microdialysis / Q000379:methods*; D008875:Middle Aged; D012189:Retrospective Studies; D013345:Subarachnoid Hemorrhage / Q000175:diagnosis*; D013814:Thermal Conductivity; D055815:Young Adult
keywords: Brain water content; Cerebral blood flow; K coefficient; Microdialysis; Subarachnoid hemorrhage; Thermal conductivity