Postoperative delirium in elective cardiac surgery is not associated with changes in peripheral cholinesterases

Background Postoperative delirium (POD) is a common complication following elective cardiac surgery, with significant implications for patient outcomes and healthcare costs. The pathophysiology of POD is multifactorial, involving neuroinflammation and imbalances in the central cholinergic system. Methods This study evaluated the relationship between peripheral cholinesterase (AChE and BChE) activities and POD occurrence in 69 cardiac surgery patients (n=20 with delirium/ n=49 without). Cholinesterase levels were measured at six perioperative time points, and their correlations with POD and inflammatory parameters (CRP, IL-6, leukocytes) were assessed. Results Neither AChE nor BChE values ​​differed significantly between patients who experienced delirium and those without delirium (all p>0.05) during 6 perioperative time points. The course of AChE values of patients with POD was stable (n=20; p=0.266), whereas the course of perioperative AChE differed significantly in non-delirant patients (n=49; p=0.005). BChE values dropped significantly in both groups: both in the group of patients with POD (n=20; p<0.001) and in the group without POD (n=49; p<0.001) the BChE values ​​fell significantly in the postoperative course. Correlations between AChE and inflammation parameters (leukocytes, CRP and Il-6) were not significant, independent of the occurrence of delirium (all p >0.05). The values of BChE in correlation to inflammatory parameter was non-significant in delirious patients, whereas postoperative leukocyte values correlated significantly with the absence of delirium (day1 p<0.001 [n=48]; day2: p=0.024[n=48]; day3: p=0.005[n=47]). Results No significant differences in cholinesterase levels were found between delirious and non-delirious patients, nor were there significant correlations with inflammatory markers. While BChE levels showed perioperative decreases, these changes were not specific to POD. Conclusion As a clinical implication, it must be concluded that the measurements of cholinesterases have limited utility in predicting POD. Furthermore, cholinesterases seem to have limited value for the management of the course of POD and possible associations with inflammation as standalone biomarkers. However, larger studies are necessary to explore their potential role in indicating inflammatory states.