OBJECTIVES We sought to examine whether the decrease in jugular venous oxygen saturation (Sjvo(2)) during cardiopulmonary bypass (CPB) can be used to predict short-term and long-term postoperative cognitive disorders in elderly patients. BACKGROUND It has been reported that elderly patients might be more susceptible to hypoperfusion during CPB. METHODS One hundred eighty-five patients scheduled for elective coronary artery bypass graft surgery, were studied. Group 1 (n = 56) was young (<50 years old), group 2 (n = 67) was middle-aged (50 to 69 years old) and group 3 (n = 62) was elderly, (>70 years old). After induction of anesthesia, a fiberoptic oximetry oxygen saturation catheter was inserted into the right jugular bulb to monitor Sjvo(2) continuously. Hemodynamic variables and arterial and jugular venous blood gases were measured at seven time points. RESULTS The cerebral desaturation time (duration when Sjvo(2) was <50%) and the ratio of the cerebral desaturation time to the total CPB time in group 3 were significantly different from those in groups 1 and 2 (group 1: 20 +/- 6 min and 16 +/- 5%; group 2: 19 +/- 7min and 14 +/- 6%; group 3: 34 +/- 9min and 24 +/- 7%, respectively; p < 0.05). Also, age (odds ratio [OR] 1.3, 95% confidence interval [CI] 1.0 to 1.8, p = 6.02) and desaturation time (OR 1.3, 95% CI 1.0 to 1.4, p = 0.03) were perioperative factors in relation to short-term cognitive impairment. However, age and desaturation time were not perioperative factors in relation to long-term cognitive impairment. CONCLUSIONS Reduced Sjvo(2) was associated with short-term cognitive dysfunction in elderly, patients. (J Am Coll Cardiol 2001;38:1450-5) (C) 2001 by the American College of Cardiology.