Brain swelling in first hour after coronary artery bypass surgery.

Six patients undergoing routine coronary artery bypass surgery were examined by magnetic resonance imaging of the brain before surgery, immediately afterwards, and 6-18 days later. Brain swelling was visible in all six patients on the immediate postoperative scan. In five patients who had later scans the swelling had subsided. No major neurological deficits were seen, and the patients were extubated successfully within 3 h of the operation. The mechanism of the cerebral swelling is uncertain, but it may provide insight into the cause of neurophysiological deficits seen after coronary artery surgery.