[Cerebral oximetry during cardiac surgery under extracorporeal circulation]

The time course of changes in rSO2 were studied in 58 patients during the uncomplicated course of cardiac operations under extracorporeal circulation (EC) and moderate hypothermia. rSO2 was also compared with central hemodynamic parameters, bioelectrical cerebral activity, and hemoglobin oxygen saturation of the bulb of the internal jugular vein (jbSO2). In the pre- and postperfusion period there was a significant correlation of rSO2 and jbSO2 (p = 0.01), yet with a low correlation coefficient (r = 0.348). During EC, no correlation was found between rSO2 and jbSO2 (p = 0.09, r = 0.386). Changes in rSO2, blood pressure, EEC, body temperature were analyzed in 2 groups of patients at the stages of an operation under EC. Group 1 comprised patients with cardiac valvular apparatus lesions and Group 2 included those with coronary heart disease who differed not only in age, but also in the history of mainly cerebrovascular atherosclerotic lesions, hypertensive disease, myocardial infarction, etc. In patients from both groups, a reduction in rSO2 occurred at the beginning of EC and at the maximum of cooling. But if in Group 1 patients, the significant reductions in rSO2 at the beginning of EC coincided both with that in mean blood pressure (BPmean), as compared to the baseline values (from 75.55 +/- 10.68 to 66.5 +/- 11.73 mm Hg, p = 0.01), and with the change in the frequency spectrum of EEC (a decrease in the frequency of the right edge, as compared to the baseline values, from 20.77 +/- 1.44 to 19.58 +/- 1.14 Hz, p = 0.01), in Group 2 patients, all significant decreases in rSO2 were accompanied only by a significant reduction in BPmean, but without changes in the frequency spectrum of EEG. It should be noted that over the uncomplicated course of an operation all changes in rSO2 were in the normal range of age-related values.