CEREBRAL SWELLING AFTER NORMOTHERMIC CARDIOPULMONARY BYPASS

Background: Marked cerebral swelling visible on magnetic resonance ima ges has been found immediately after hypothermic (28 degrees C) cardio pulmonary bypass. The mechanism is unknown, but indices of cerebral is chemia are seen during rewarming from hypothermic bypass that are not present with normothermic bypass (37 degrees C). Methods: T1-weighted and fluid-attenuated inversion recovery magnetic resonance images were taken of seven patients undergoing routine coronary artery bypass sur gery before, 1 h, and 7 days after the operation using normothermic by pass. Results: Marked cerebral swelling was seen in fluid-attenuated i nversion recovery images in five of seven patients 1 h after bypass. S cans in four patients taken 7 days after bypass showed that the cerebr al swelling had returned to normal. There was no change in cerebral ve ntricular size, and all patients had uncomplicated postoperative cours es. Conclusions: Normothermic bypass is followed by acute postoperativ e cerebral swelling. However, the amount of swelling was similar to th at found in a previous study after hypothermic bypass. The mechanism o f smelling is still obscure, and its relation to neurologic outcome is unknown.