title: Brain tissue oxygen pressure and cerebral metabolism in an animal model of cardiac arrest and cardiopulmonary resuscitation.
abstract: OBJECTIVE
  Direct measurement of brain tissue oxygenation (PbtO2) is established during spontaneous circulation, but values of PbtO2 during and after cardiopulmonary resuscitation (CPR) are unknown. The purpose of this study was to investigate: (1) the time-course of PbtO2 in an established model of CPR, and (2) the changes of cerebral venous lactate and S-100B.
  
  
  METHODS
  In 12 pigs (12-16 weeks, 35-45 kg), ventricular fibrillation (VF) was induced electrically during general anaesthesia. After 4 min of untreated VF, all animals were subjected to CPR (chest compression rate 100/min, FiO2 1.0) with vasopressor therapy after 7, 12, and 17 min (vasopressin 0.4, 0.4, and 0.8 U/kg, respectively). Defibrillation was performed after 22 min of cardiac arrest. After return of spontaneous circulation (ROSC), the pigs were observed for 1h.
  
  
  RESULTS
  After initiation of VF, PbtO2 decreased compared to baseline (mean +/- SEM; 22 +/- 6 versus 2 +/- 1 mmHg after 4 min of VF; P < 0.05). During CPR, PbtO2 increased, and reached maximum values 8 min after start of CPR (25 +/- 7 mmHg; P < 0.05 versus no-flow). No further changes were seen until ROSC. Lactate, and S-100B increased during CPR compared to baseline (16 +/- 2 versus 85 +/- 8 mg/dl, and 0.46 +/- 0.05 versus 2.12 +/- 0.40 microg/l after 13 min of CPR, respectively; P < 0.001); lactate remained elevated, while S-100B returned to baseline after ROSC.
  
  
  CONCLUSIONS
  Though PbtO2 returned to pre-arrest values during CPR, PbtO2 and cerebral lactate were lower than during post-arrest reperfusion with 100% oxygen, which reflected the cerebral low-flow state during CPR. The transient increase of S-100B may indicate a disturbance of the blood-brain-barrier.
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: Berthold
authors.initials: B
authors.lastname: Bein
authors.forename: Volker
authors.initials: V
authors.lastname: Dörges
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Stadlbauer
authors.forename: Volker
authors.initials: V
authors.lastname: Wenzel
authors.forename: Markus
authors.initials: M
authors.lastname: Steinfath
authors.forename: Robert
authors.initials: R
authors.lastname: Hanss
authors.forename: Jens
authors.initials: J
authors.lastname: Scholz
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D016887:Cardiopulmonary Resuscitation; D002560:Cerebrovascular Circulation; D004195:Disease Models, Animal; D004554:Electric Countershock; D005260:Female; D006323:Heart Arrest / Q000378:metabolism* / Q000503:physiopathology; D007773:Lactates / Q000378:metabolism; D008297:Male; D010100:Oxygen / Q000032:analysis*; D013552:Swine; D014667:Vasopressins / Q000008:administration & dosage; D014693:Ventricular Fibrillation / Q000378:metabolism
chemical_list: D007773:Lactates; D014667:Vasopressins; D010100:Oxygen