• Simon Mölström, Troels H Nielsen, Claus Andersen, Carl H Nordström, and Palle Toft.
• Department of Anesthesiology and Intensive Care, Odense University Hospital, Odense, Denmark. Electronic address: Smolstrom@gmail.com.
• J. Cardiothorac. Vasc. Anesth. 2017 Aug 1; 31 (4): 1166-1173.

ObjectivesThis 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).DesignInterventional, prospective, randomized study.SettingSingle-center, university teaching hospital.ParticipantsThe study included 10 patients undergoing primary, elective coronary artery bypass grafting.InterventionsPatients 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.Measurements And Main ResultsThe correlated difference between pooled LP ratio (low and high MAP) of the jugular venous and the arterial blood was significant (LParterial 17 [15-20] v LPvenous 26 [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.ConclusionThe LP ratio of cerebral venous blood increased significantly during CPB, indicating compromised cerebral oxidative metabolism. Conventional monitoring of rSO2 by 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.Copyright © 2017 Elsevier Inc. All rights reserved.

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