[Evaluation of cerebral oxygen balance during normothermic cardiopulmonary bypass using jugular oxygen saturation]

Previous studies suggest that normothermic cardiopulmonary bypass(CPB) impairs cerebral oxygen balance. We studied the effect of normothermic CPB on cerebral oxygen balance evaluated by continuous measurement of oxygen saturation in the jugular vein (SjO2).

Eleven patients undergoing coronary artery bypass grafting with normothermic CPB were studied. A 4 Fr oxymetry catheter was inserted into the internal jugular bulb for SjO2 monitoring. We measured mean arterial pressure (MAP), SjO2 and hemoglobin (Hgb) concentration at five time points-1) pre CPB, 2) 3) 4) 5, 30, 60 min after the onset of CPB, respectively, 5) 5 min after the end of CPB.

MAP decreased significantly 30 min (47 +/- 9 mmHg) and 60 min (48 +/- 9 mmHg) after the onset of CPB compared with the pre CPB (80 +/- 14 mmHg) value. Hgb also decreased significantly 5 min (7.8 +/- 1.1 g x dl(-1)) and 30 min (7.1 +/- 1.0 g x dl(-1)) and 60 min (7.1 +/- 0.8 g x dl(-1)) after the onset of CPB compared with the pre CPB (11 +/- 1.0 g x dl(-1)) value. However, SjO2 showed no significant change throughout the study period. No significant correlation was observed between MAP and SjO2.

Cerebral oxygen balance assessed by SjO2 was not impaired during normothermic CPB, and was unaffected by hypotension and hemodilution.