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A randomized study of neuropsychological function in patients undergoing coronary bypass surgery
1Department of Thoracic Surgery, Karolinska Institute, Stockholm, Sweden.
Insights
Neuropsychological deficits after coronary artery surgery with extracorporeal circulation (ECC) improved within six months. While some cognitive functions showed faster recovery with membrane oxygenation, overall ECC type and filtration did not significantly impact long-term outcomes.
Area of Science:
- Cardiology
- Neurology
- Medical Engineering
Background:
- Coronary artery surgery often requires extracorporeal circulation (ECC).
- Potential for postoperative cognitive dysfunction exists following ECC.
- Different ECC methods may influence neurological outcomes.
Purpose of the Study:
- To investigate the incidence and pattern of neuropsychological deficits after coronary artery surgery.
- To compare the effects of different extracorporeal circulation (ECC) methods on cognitive function.
- To assess the impact of arterial line filtration on postoperative intellectual dysfunction.
Main Methods:
- Fifty-four male patients undergoing coronary artery surgery were randomized into three ECC groups: bubble oxygenation without filter, bubble oxygenation with filter, and membrane oxygenation without filter.
- Neuropsychological tests were administered preoperatively and at 1 and 6 months post-surgery.
- Patients were assessed for neuropsychological deficits and intellectual dysfunction.
Main Results:
- Overall, 17% of patients experienced deficits at 1 month, decreasing to 7% at 6 months.
- Postoperative intellectual dysfunction rates varied by group but were not statistically significant.
- The membrane oxygenation group showed faster improvement in attention and memory at 1 month compared to bubble oxygenation without a filter.
Conclusions:
- A risk of neuropsychological dysfunction exists after extracorporeal circulation, with improvement observed within six months.
- The type of oxygenation and use of arterial line filtration did not significantly alter long-term outcomes in this low-risk cohort.
- Early cognitive improvements in specific domains were noted with membrane oxygenation, suggesting potential benefits for certain functions.
Abstract:
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.