Jugular venous oxygen saturation during mild hypothermic versus normothermic cardiopulmonary bypass in elderly patients.

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Age is known to be a major risk factor for adverse postoperative cognitive dysfunction after cardiac surgery. We conducted this study to determine if jugular venous oxygen saturation (SjvO(2)) differed during mild hypothermic (32 degrees C) and normothermic cardiopulmonary bypass (CPB) in elderly patients. Sixty patients aged over 70 years who underwent elective coronary artery bypass grafting were randomly divided into two groups. Group 1 ( n = 30) underwent normothermic CPB (>35 degrees C) and group 2 ( n = 30) underwent mild hypothermic CPB (32 degrees C). For the continuous monitoring of SjvO(2), a fiberoptic oximetry oxygen saturation catheter was inserted into the right jugular bulb after the induction of anesthesia. Hemodynamic parameters, and arterial and jugular venous blood gases were measured at seven time points. The SjvO(2) in the normothermic group was lower at the onset of CPB and 20 min after the onset, than from the time of induction of anesthesia until the start of surgery (period 1), the respective SjvO(2) values being 50.3% +/- 1.0%, 50.1% +/- 1.6%, and 59.5% +/- 1.9% ( P < 0.05). However, in the mild hypothermic group there were no changes in the SjvO(2) value throughout the study. The cerebral desaturation time (when the SjvO(2) value was <50%) and the ratio of the cerebral desaturation time to the total CPB time in the normothermic group differed significantly from those in the hypothermic group, being 19 +/- 11 min and 17% +/- 10%, and 9 +/- 3 min and 8% +/- 4%, respectively ( P < 0.05). The SjvO(2) value was better during mild hypothermic CPB than during normothermic CPB in elderly patients.