Association Between Preoperative Mechanical Bowel Preparation and Postoperative Cognitive Dysfunction in Patients Undergoing Colorectal Surgery: A Pilot Randomized Controlled Trial.

INTRODUCTION: Postoperative cognitive dysfunction (POCD) is a common condition that greatly threatens patients' quality of life. While mechanical bowel preparation (MBP) enhances surgical visibility, its effect on postoperative complication rates remains debated. This study aims to evaluate the effect of MBP on POCD in patients undergoing colorectal surgery and to investigate its association with tau protein, brain-derived neurotrophic factor (BDNF) and lipopolysaccharide-binding protein (LBP) levels. METHODS: This is a single-center randomized controlled trial. 80 eligible ASA-PS II-III colorectal surgery patients were randomized into his pilot study, which was designed as a randomized controlled trial. Cognitive function was assessed preoperatively (T1), postoperatively on day 15 (T2), and on day 90 (T3) using the Montreal Cognitive Assessment (MoCA). Blood samples were collected simultaneously from the patients for biomarker analysis. A decline of > 1 standard deviation from baseline on the MoCA was defined as POCD. RESULTS: The incidence of POCD was significantly lower in patients without MBP compared to those with MBP (7.5% vs. 55%). At T3, BDNF levels were significantly higher in Group I than in Group II (p < 0.001). LBP levels were significantly higher in Group II than in Group I at T3 (p = 0.001). In patients with POCD, tau protein levels were significantly higher at T2 and T3 (p = 0.007; p = 0.012), while BDNF levels were significantly lower at T3 (p < 0.001). CONCLUSION: MBP was associated with a higher incidence of POCD in patients undergoing colorectal surgery; however, these preliminary findings require confirmation in larger trials.