IMPACT OF RELATIVE BLOOD FLOW VELOCITY HYPERPERFUSION DURING CARDIAC SURGERY WITH CARDIOPULMONARY BYPASS TO DELAYED NEUROCOGNITIVE RECOVERY

Abstract

<h3>Objective</h3> Inflammation, neuronal, vascular damage/embolism, cerebral autoregulation and perfusion, oxygen delivery are known as etiological factors of delayed neurocognitive recovery (dNCR). Many researchers have identified that neuropsychological complications emerge from insufficient cerebral perfusion. Relative cerebral hyperperfusion also disrupts cerebral autoregulation and might play a significant role in dNCR development. The aim of this study was to determine the influence of increased a. cerebri media (ACM) blood flow velocity (BFV) during cardiac surgery with cardiopulmonary bypass (CPB) on delayed neurocognitive recovery. <h3>Design and Method</h3> This prospective - case control study included patients undergoing elective coronary artery bypass grafting (CABG) or/and valve surgery with CPB. For cognitive evaluation 110 patients completed ACE-III. To determine mild cognitive dysfunction, cut - off 88 was chosen. Mean BFV was monitored with transcranial Doppler ultrasonography (TCD) and performed before surgery and at the beginning, middle and ending of CPB. The average of three CPB measurements was used for calculation. Preoperative BFV was converted to 100% and used as a baseline. The percentage change of cerebral blood flow velocity during CPB was calculated from baseline. Patients with decreased blood flow velocity were included for further investigation. <h3>Results</h3> 101 patients were examined, 67 (69,1%) men and 29 (29,9%) women, age 67.9 (SD 9.2) Increased percentage of BFV was determined for 40 (39.60%) patients. Patients' demographic data are shown in Table 1. Percentage change of BFV was 105.60 % (min 100.21; max 148.02) in the non-dNCR group and 132.29 % (min 101.34; max 150.26) in the dNCR group, p=0.033 (Figure Nr. 1). During the study, we assessed the relationship between patients age and ACE-III test results together with ACM BFV. Spearman correlation analysis revealed that age had negative moderate correlation with ACE-III test results after surgery (Spearman r -0.597, p< 0.01) and negative moderate correlation with ACM BFV during CPB (Sprearman r -0 .529, p <0.01) (Figure 2 and 3). <h3>Conclusions</h3> Patients that develop dNCR were significantly older and had a lower baseline BFV. Results suggest that the main cause of hyperperfusion during CPB is age related lower BFV before surgery. Elderly patients are more sensitive to relative hyperperfusion during CPB, therefore dNCR was diagnosed more often in patients with higher percentage change of BFV.