Ineffectiveness of Burst Suppression Therapy in Mitigating Perioperative Cerebrovascular Dysfunction

Abstract

Background Cerebral injury is among the most common and disabling complications of open heart surgery. Attempts to provide neuroprotection have yielded conflicting results. We assessed the potential of propofol-induced burst suppression during open heart surgery to provide cerebral protection as determined by postoperative neuropsychologic function. Methods Two hundred twenty-five patients undergoing valve surgery were randomized to receive either sufentanil or sufentanil plus propofol titrated to electroencephalographic burst suppression. Blinded investigators performed neurologic and neuropsychologic testing at baseline, postoperative day (POD) 1 (neurologic testing only), PODs 5-7, and PODs 50-70. Neuropsychologic tests were compared with the results of 40 nonsurgical patients matched for age and education. Results Electroencephalographic burst suppression was successfully achieved in all 109 propofol patients. However, these patients sustained at least as many adverse neurologic outcomes as the 116 controls: POD 1, 40% versus 25%, P = 0.06; PODs 5-7, -18% versus 8%, P = 0.07; PODs 50-70, -6% versus 6%, P = 0.80. No differences in the incidence of neuropsychologic deficits were detected, with 91% of the propofol patients versus 92% of the control patients being impaired at PODs 5-7, decreasing to 52 and 47%, respectively, by PODs 50-70. No significant differences in the severity of neuropsychologic dysfunction, depression, or anxiety were noted. Conclusions Electroencephalographic burst suppression surgery with propofol during cardiac valve replacement did not significantly reduce the incidence or severity of neurologic or neuropsychologic dysfunction. The authors' results suggest that neither cerebral metabolic suppression nor reduction in cerebral blood flow reliably provide neuroprotection during open heart surgery. Other therapeutic approaches must be evaluated to address this important medical problem.