Cognitive effects after epidural vs general anesthesia in older adults. A randomized trial.

OBJECTIVE

To compare the effect of epidural vs general anesthesia on the incidence of long-term cognitive dysfunction after total knee replacement surgery in older adults.

DESIGN

Randomized controlled clinical trial.

SETTING

Orthopedic specialty academic hospital.

PATIENTS

A total of 262 patients undergoing elective primary total knee replacement with a median age of 69 years; 70% women.

INTERVENTION

Random assignment to either epidural or general anesthesia.

MAIN OUTCOME MEASURES

A thorough neuropsychological assessment was performed preoperatively and repeated at 1 week and 6 months postoperatively. Cognitive outcome was assessed by within-patient change on 10 tests of memory, psychomotor, and language skills. Prospective standardized surveillance for cardiovascular complications was performed to allow simultaneous assessment of anesthetic effects on cognitive and cardiovascular outcomes.

RESULTS

The two groups were similar at baseline in terms of age, sex, comorbidity, and cognitive function. There were no significant differences between the epidural and general anesthesia groups in within-subject change from baseline on any of the 10 cognitive test results at either 1 week or 6 months. Overall, 5% of patients showed a long-term clinically significant deterioration in cognitive function. There was no difference between the anesthesia groups in the incidence of major cardiovascular complications (3% overall).

CONCLUSIONS

The type of anesthesia, general or epidural, does not affect the magnitude or pattern of postoperative cognitive dysfunction or the incidence of major cardiovascular complications in older adults undergoing elective total knee replacement. This is the largest trial of the effects of general vs regional anesthesia on cerebral function reported to date, with more than 99% power to detect a clinically significant difference on any of the neuropsychological tests.