Microemboli are not associated with delirium after coronary artery bypass graft surgery

Delirium is an acute change in cognition which occurs frequently after coronary artery bypass graft (CABG) surgery. Cerebral microemboli, from plaque, air, or thrombus, have been hypothesized to contribute to delirium and cognitive decline after CABG. The purpose of this study was to determine if there was an association between cerebral microemboli and delirium after cardiac surgery. Non-delirious patients (n=68) were prospectively enrolled and underwent intraoperative monitoring of the middle cerebral arteries with transcranial Doppler (TCD). TCD signals were saved and analyzed postoperatively for microemboli manually, according to established criteria. Postoperatively, patients were assessed for delirium with a standardized battery. Thirty-three patients (48.5%) developed delirium after surgery. Microemboli counts (mean +/- SD) were not significantly different in those with and without delirium (303 +/- 449 vs. 299 +/- 350; p= 0.97). While intraoperative microemboli were not associated with delirium after CABG, further investigation into the source and composition of microemboli can further elucidate the long-term clinical impact of microemboli.