Early postoperative cognitive dysfunction and blood pressure during coronary artery bypass graft operation

Objective: To determine the relationship between change in blood pressure during coronary artery bypass graft operations and early cognitive dysfunction. Design: Cohort study. Setting: Quaternary care facility. Patients: Fifteen patients undergoing coronary artery bypass graft operations who were at high risk for postoperative stroke. Preoperative and intraoperative mean arterial pressures (MAPs) were measured in all patients. Intervention: A subset of patients underwent preoperative and postoperative magnetic resonance imaging. Main Outcome Measure: Change in cognitive performance, using the Mini-Mental State Examination and other simple cognitive tests. Results: A drop in MAP (preoperatively to intraoperatively) predicted a decrease in Mini-Mental State Examination score. When change in MAP was dichotomized (after excluding an outlier), subjects with a small decrease improved on the Mini-Mental State Examination by 1 point, whereas those with a large drop in MAP worsened by 1.4 points (P=.04). Conclusion: A drop in MAP from a preoperative baseline may put patients at risk for early cognitive dysfunction after a coronary artery bypass graft operation.