title: Bedside Monitoring of Cerebral Energy State During Cardiac Surgery-A Novel Approach Utilizing Intravenous Microdialysis.
abstract: OBJECTIVE
  This study investigated whether the lactate-to-pyruvate (LP) ratio obtained by microdialysis (MD) of the cerebral venous outflow reflected a derangement of global cerebral energy state during cardiopulmonary bypass (CPB).
  
  
  METHODS
  Interventional, prospective, randomized study.
  
  
  METHODS
  Single-center, university teaching hospital.
  
  
  METHODS
  The study included 10 patients undergoing primary, elective coronary artery bypass grafting.
  
  
  METHODS
  Patients were randomized blindly to low mean arterial pressure (MAP) (40-60 mmHg; n = 5) or high MAP (60-80 mmHg; n = 5) during CPB. The MD catheters were positioned in a retrograde direction into the jugular bulb, and a reference catheter was inserted into the brachial artery. The correlations among LP ratio, MAP, data obtained from bifrontal near-infrared spectroscopy (NIRS), and postoperative neurologic outcome measures were assessed.
  
  
  RESULTS
  The correlated difference between pooled LP ratio (low and high MAP) of the jugular venous and the arterial blood was significant (LParterial17 [15-20] v LPvenous26 [23-27]; p = 0.0001). No cerebral desaturations (decrease in rSO2>20% from baseline) were observed in either group during CPB. In each group, 50% of the patients showed significant cognitive decline (mini-mental state examination, 3 points) 2 days after surgery.
  
  
  CONCLUSIONS
  The LP ratio of cerebral venous blood increased significantly during CPB, indicating compromised cerebral oxidative metabolism. Conventional monitoring of rSO2by NIRS did not show a corresponding decrease in cerebral oxygenation. As the patients exhibited decreased cognitive functions after CPB, increases in jugular venous LP ratio may be a sensitive indicator of impending cerebral damage.
authors.affiliation: Department of Anesthesiology and Intensive Care, Odense University Hospital, Odense, Denmark. Electronic address: Smolstrom@gmail.com.
authors.forename: Simon
authors.initials: S
authors.lastname: Mölström
authors.affiliation: Department of Neurosurgery, Odense University Hospital, Odense, Denmark.
authors.forename: Troels H
authors.initials: TH
authors.lastname: Nielsen
authors.affiliation: Department of Anesthesiology and Intensive Care, Thorax Anesthesiology Unit VITA, Odense University Hospital, Odense, Denmark.
authors.forename: Claus
authors.initials: C
authors.lastname: Andersen
authors.affiliation: Department of Neurosurgery, Odense University Hospital, Odense, Denmark.
authors.forename: Carl H
authors.initials: CH
authors.lastname: Nordström
authors.affiliation: Department of Anesthesiology and Intensive Care, Odense University Hospital, Odense, Denmark.
authors.forename: Palle
authors.initials: P
authors.lastname: Toft
mesh_terms: D000368:Aged; D001921:Brain / Q000378:metabolism*; D006348:Cardiac Surgical Procedures / Q000009:adverse effects / Q000639:trends; D002550:Cerebral Veins / Q000378:metabolism; D001026:Coronary Artery Bypass / Q000009:adverse effects / Q000639:trends*; D004734:Energy Metabolism / Q000502:physiology*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007601:Jugular Veins / Q000378:metabolism; D008297:Male; D017551:Microdialysis / Q000379:methods* / Q000706:statistics & numerical data; D010092:Oximetry / Q000379:methods / Q000706:statistics & numerical data; D000067716:Point-of-Care Testing / Q000706:statistics & numerical data; D011446:Prospective Studies
keywords: cardiac surgery; cardiopulmonary bypass; cerebral oxidative metabolism; microdialysis; neurologic outcome; regional cerebral oxygen saturation