Cerebrovascular autoregulation impairments during cardiac surgery with cardiopulmonary bypass are related to postoperative cognitive deterioration: prospective observational study

BACKGROUND: Postoperative cognitive dysfunction (POCD) occurs in approximately 33-83% of patients after cardiac surgery with cardiopulmonary bypass (CPB). Recent clinical data suggest that real-time, intraoperative monitoring of patient-specific cerebrovascular autoregulation (CA) may help to prevent POCD by detecting individual critical limits for mean arterial pressure (MAP) outside which CA is impaired. Objectives of the study were to detect the episodes of impaired CA during cardiac surgery with CPB, and to investigate the association between CA impairment and POCD. METHODS: The observational study of non-invasive ultrasonic volumetric CA monitoring included 59 patients undergoing elective coronary artery bypass graft surgery with CPB. All patients underwent series of neuropsychological tests the day before and ten days after the surgery in order to evaluate cognitive function. RESULTS: Twenty-two patients (37%) experienced POCD, 37 patients (63%) showed no cognitive deterioration. The duration of the single longest CA impairment event was found reliably associated with occurrence of POCD (P<0.05). The critical duration of the single longest CA impairment event was 5.03 minutes (odds ratio 14.5; CI 3.9-51.8) for studied population. CONCLUSIONS: Prospective clinical study showed that single longest CA impairment may result in post-operative deterioration of mental abilities. The duration of the single longest CA impairment event is the risk factor that is associated with POCD.