Impaired peripheral perfusion during anesthesia is associated with postoperative delirium in older patients undergoing minimally invasive colorectal surgery: a retrospective observational study.

Introduction: Postoperative delirium (POD) is a frequent postoperative complication in older patients and is associated with poor outcomes. Mean arterial pressure may not adequately reflect microcirculatory perfusion during anesthesia, and the perfusion index (PI), derived from pulse oximetry, is a promising noninvasive surrogate. This study aimed to investigate the association of intraoperative PI with POD in older adults undergoing minimally invasive colorectal surgery. Methods: This retrospective observational study included patients aged ≥65 years who underwent elective laparoscopic or robot-assisted colorectal surgery between July 2024 and July 2025. POD was assessed using the Intensive Care Delirium Screening Checklist twice daily for the first three postoperative days and defined as a score of ≥4. PI values were recorded every 3 s during anesthesia, and the mean PI was calculated for each patient. Predictive performance was evaluated using receiver operating characteristic analysis. Separate two-variable logistic regression models based on mean PI and one covariate were developed. Results: Ninety-eight patients (11 had POD) were included. The mean PI was lower for those with than for those without POD (median 1.5 [1.3-1.8] vs. 2.3 [1.7-3.1]; Conclusions: Lower intraoperative mean PI was associated with POD and demonstrated moderate predictive ability. PI may complement conventional monitoring for perioperative POD risk assessment. Future studies are required to determine whether PI-guided intraoperative management can improve postoperative outcomes.