Discussion
inflammation
INFLAMMATION, DYSFUNCTION, CORTEX
The present study shows for the first time in human subjects that dexmedetomidine combined with general anaesthesia leads to a stable perioperative AChE activity in blood of patients with major abdominal or cardiac surgery. In contrast, general anaesthesia alone leads to a significant decrease in enzyme activity.This is in line with findings of Nemoto and colleagues who studied the effect of intravenous propofol, midazolam and dexmedetomidine on the extracellular concentration of acetylcholine in the cerebral cortex of ratsWe observed that patients treated with dexmedetomidine had stable AChE and rapidly recovering BChE activity, whereas they showed a lower incidence of POD in the primary studyAChE plays a key role in cholinergic transmission by hydrolysing ACh at maximum rate, thereby maintaining not only cholinergic transmission but also the recycling process of ACh synthesis, where the absence of one component can lead to cholinergic dysfunction. Early animal studies demonstrated a central decrease in ACh synthesis and release in old ageBChE acitivity continuously decreased in placebo treated patients, whereas in dexmedetomidine treated patients, there was an increase on the first postoperative day compared to directly postoperative. On the one hand, this might be related to the fact that BChE activity is more susceptible to confounding factors, such as the outcome of hemodilutional cardiopulmonary bypass or malignancyRegarding the underlying physiological mechanism, Xiang and colleagues demonstrated that intraperitoneal administration of dexmedetomidine in mice augmented the electric activity of the cervical vagus nerveAlthough the few publications on the role of cholinesterases in POD yield inconsistent findings, they highlight the close relationship between the cholinergic system, perioperative inflammation and POD. In a cohort observational study of patients undergoing arthroplasty surgery, Cerejeira and colleagues found a correlation between low preoperative esterase activity and a change in blood CRP concentrationIn contrast to our results, a study in cardiac surgery patients showed no difference in postoperative measurements of AChE and BChE between patients with and without POD