Objective: We sought to evaluate magnesium as a neuroprotectant in patients un dergoing cardiac surgery with cardiopulmonary bypass. Methods: From February 200 2 to September 2003, 350 patients undergoing elective coronary artery bypass gra fting, valve surgery, or both were enrolled in a randomized, blinded, placebo-c ontrolled trial to receive either magnesium sulfate to increase plasma levels 1( 1/2) to 2 times normal during cardiopulmonary bypass(n=174) or no intervention(n =176). Neurologic function, neuropsychologic function, and depression were asses sed preoperatively,at 24 and 96 hours after extubation(neurologic) and at 3 mont hs(neuropsychologic, depression). Neurologic scores were analyzed using ordinal longitudinal methods, and neuropsychologic and depression inventory data were su mmarized by principal component analysis, followed by linear regression analysis using component scores as response variables. Results: Seven(2%) patients had a postoperative stroke, 2(1%) in the magnesium and 5(3%) in the placebo group( P=.4). Neurologic score was worse postoperatively in both groups(P .6); however, older age(P=.0006), previous stroke(P=.003), and lower ed ucation level(P=.0007) were associated with worse performance. Conclusions: Magn esium administration is safe and improves short-term postoperative neurologic f unction after cardiac surgery, particularly in preserving short-term memory and cortical control over brainstem functions. However, by 3 months, other factors and not administration of magnesium influence neuropsychologic and depression in ventory performance.
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