Abstract
The quest to minimize the morbidity and mortality of patients undergoing cardiac surgery is ongoing. Impaired cerebral autoregulation and tissue malperfusion are linked with neurological complications. The cerebral oximetry index (COx) has been introduced as an index of cerebral autoregulation, while in-line monitoring enables the detection and prevention of metabolic disturbances during cardiopulmonary bypass (CPB). This report presents the case of a 58-year-old female patient scheduled for aortic valve replacement under minimally invasive extracorporeal circulation (MiECC). Her medical history consisted of epilepsy, multiple ischemic strokes, heavy smoking, and brachiocephalic artery stenosis. We sought to investigate the limits of autoregulation and the role of metabolic indices of perfusion on COx. Mean arterial blood pressure (ABP), cerebral oximetry (rSO(2)), and in-line perfusion data during CPB were recorded at 10s intervals. The lower limit of autoregulation was 44mmHg on both sides and the upper limit was 98mmHg on the right and 107mmHg on the left side. A multiple linear regression analysis was performed to identify any potential predictors of COx values. Hemoglobin (Hb), PCO(2), flow, DO(2) index (DO(2)i), Ο(2) extraction ratio (O(2)ER), and perfusion ratio (PR) were included in the analysis. Significant equations were found on both sides. Predicted COx left was equal to 5.8 - 11.04O(2)ER - 0.04Hb (p=0.001, R(2)= 0.15). Predicted COx right was equal to 3.06 - 0.3flow - 6.8O(2)ER -0.03Hb + 0.02PCO(2) + 0.004DO(2)i(p=0.03, R(2)=0.13). Targeting physiological perfusion and monitoring perfusion during CPB may have an additional impact on cerebral autoregulation and should be studied further.