Cognitive function is minimally impaired after ambulatory surgery

Abstract

Purpose: To evaluate the magnitude of subjective cognitive failure in the three days following general anesthesia (GA) for ambulatory surgery. Methods: After Research Ethics Board approval, 258 patients undergoing general anesthesia (GA) and 250 patients scheduled for local anesthesia (LA) were recruited from our ambulatory surgical unit. Following the method of Tzabar, Asbury and Millar, patients were asked to complete the cognitive failures questionnaire (CFQ) before their procedure (with respect to the previous three days) and on the third postoperative day (with respect to their recovery period). Results: General anesthesia and LA groups were similar in demographic make-up, except that the LA group contained more patients of American Society of Anesthesiologists physical status 1 (64.5% vs 52.7%, P < 0.05) and had significantly shorter procedure duration (25 vs 51 min, P < 0.01) than the GA group. Median preoperative CFQ scores (interquartile range) were 26 (18) for the LA group and 26 (18) for the GA group. Postoperative CFQ scores were 25 (20) for the LA group and 28 (22) for the GA group. There was no significant difference in preoperative CFQ score between groups (Mann-Whitney U). When preoperative and postoperative CFQ scores were compared, the small increase seen in the GA group was statistically significant (P < 0.05, Wilcoxon). Conclusion: A statistically significant impairment of cognitive function in the three days following GA, but not LA was found. However, the magnitude of this impairment was small, and is of doubtful clinical significance. Modern ambulatory anesthesia may cause less delayed cognitive impairment than was previously thought.