title: Effects of cerebral hypoperfusion on bispectral index: a randomised, controlled animal experiment during haemorrhagic shock.
abstract: BACKGROUND
  The aim of this porcine haemorrhagic shock model was to investigate the changes of bispectral index (BIS) after slow and fast recovery of cerebral perfusion, and its correlation with plasma propofol concentrations.
  
  
  METHODS
  After Animal Investigational Committee approval, 16 pigs during propofol anaesthesia underwent a liver trauma with severe hypotension, and were randomly assigned to receive therapy for either slow recovery (fluid resuscitation; slow group; n=8) or fast recovery of cerebral perfusion (vasopressor combined with hypertonic-saline-starch; fast group; n=8), respectively. Cerebral perfusion pressure (CPP=MAP-ICP), cerebral tissue oxygenation index (TOI), BIS, and plasma concentrations of propofol and haemoglobin were measured at baseline (Pre-shock), haemodynamic decompensation (Shock), and 5 (Therapy) and 30 min (End) after therapy, respectively.
  
  
  RESULTS
  CPP, TOI, and BIS decreased significantly during shock (pre-shock vs. shock, fast: CPP: 65+/-14 vs. 15+/-4 mmHg; TOI: 64+/-6 vs. 47+/-7%; BIS 60+/-5 vs. 9+/-10; slow: CPP: 60+/-12 vs. 13+/-7 mmHg; TOI: 68+/-7 vs. 49+/-7%; BIS 63+/-5 vs. 13+/-12; P<0.05). In the fast group, CPP, TOI, and BIS increased after therapy compared to the slow group (Therapy, fast: CPP: 47+/-15 mmHg, TOI: 61+/-7%, BIS: 47+/-21; slow: CPP: 18+/-9 mmHg, TOI: 51+/-5%, BIS: 21+/-19; P<0.05). Propofol and haemoglobin concentrations were comparable between groups throughout the resuscitation phase.
  
  
  CONCLUSIONS
  In a haemorrhagic shock scenario, therapies with different impact on cerebral perfusion resulted in differing changes of BIS values, while plasma propofol and haemoglobin concentrations were comparable during the resuscitation phase; this suggests that BIS may also have reflected changes of cerebral perfusion.
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Hospital Schleswig-Holstein, Campus Kiel, Schwanenweg 21, 24105 Kiel, Germany. e.cavus@t-online.de
authors.forename: Erol
authors.initials: E
authors.lastname: Cavus
authors.forename: Patrick
authors.initials: P
authors.lastname: Meybohm
authors.forename: Volker
authors.initials: V
authors.lastname: Doerges
authors.forename: Jan
authors.initials: J
authors.lastname: Hoecker
authors.forename: M
authors.initials: M
authors.lastname: Betz
authors.forename: Robert
authors.initials: R
authors.lastname: Hanss
authors.forename: Markus
authors.initials: M
authors.lastname: Steinfath
authors.forename: Berthold
authors.initials: B
authors.lastname: Bein
mesh_terms: D018686:Anesthetics, Intravenous / Q000097:blood; D000818:Animals; D001127:Arginine Vasopressin / Q000627:therapeutic use; D001783:Blood Flow Velocity; D001794:Blood Pressure; D001921:Brain / Q000378:metabolism; D002545:Brain Ischemia / Q000175:diagnosis* / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology*; D002560:Cerebrovascular Circulation; D004569:Electroencephalography; D005440:Fluid Therapy; D006454:Hemoglobins / Q000032:analysis; D010100:Oxygen / Q000097:blood / Q000378:metabolism; D015742:Propofol / Q000097:blood; D012039:Regional Blood Flow; D012151:Resuscitation / Q000379:methods; D012771:Shock, Hemorrhagic / Q000150:complications*; D013552:Swine; D014662:Vasoconstrictor Agents / Q000627:therapeutic use
chemical_list: D018686:Anesthetics, Intravenous; D006454:Hemoglobins; D014662:Vasoconstrictor Agents; D001127:Arginine Vasopressin; D010100:Oxygen; D015742:Propofol