A randomized study of neuropsychological function in patients undergoing coronary bypass surgery

Fifty-four male patients were examined by an extensive battery of neuropsychological tests before and 1 and 6 months after coronary artery surgery. The patients were randomized to one of three methods of extracorporeal circulation (ECC): bubble oxygenation without an arterial line filter (Group I, n = 17), bubble oxygenation with an arterial filter (Group II, n = 17), or membrane oxygenation without an arterial filter (Group III, n = 20). The mean age was 59 (range 44-69) years. At 1 month nine patients (17%) and at 6 months four patients (7%) had neuropsychological deficits (reduction of 1 standard deviation in two or more tests). Postoperative intellectual dysfunction was found in groups I, II, and III at 1 and 6 months in 24% and 12%, 12% and 6%, and 15% and 5%, respectively. The differences between groups were not statistically significant. Significantly more patients in the membrane oxygenator group than in the bubble-oxygenator group without a filter performed better in the test for attention, visual scanning, and psychomotor speed and in the test for learning and memory at 1-month follow-up. In conclusion, there exists a risk of neuropsychological dysfunction after ECC, with improvement within the first 6 months, which is independent of the type of oxygenation and the use of arterial line filtration during ECC in this low-risk group.