Acetylcholinesterase and butyrylcholinesterase in cardiosurgical patients with postoperative delirium

Background: Patients in intensive care units (ICU) are often diagnosed with postoperative delirium; the duration of which has a relevant negative impact on various clinical outcomes. Recent research found a potentially important role of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) in delirium of critically ill patients on nonsurgical ICU or in non-cardiac-surgery patients. We tested the hypothesis that AChE and BChE have an impact on patients after cardiac surgery with postoperative delirium. Methods: After obtaining approval from the local ethics committee, this mechanistic study gathered data of all 217 patients included in a randomized controlled trial testing non-pharmacological modifications of care in the cardiac surgical ICU to reduce delirium. Delirium was assessed with the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) and the Nursing Delirium Screening Scale (Nu-DESC) twice a day for the first 3 days after surgery. Further outcome variables were somatic laboratory parameters and variables regarding surgery, anesthesia, and postsurgical recovery. 10 μl venous or arterial blood was drawn and AChE and BChE were determined with ChE check mobile from Securetec. Results: Of 217 patients, 60 (27.6%) developed postsurgical delirium (POD). Patients with POD were older (p = 0.005), had anemia (p = 0.01), and worse kidney function (p = 0.006). Furthermore, these patients had lower intraoperative cerebral saturation (NIRS) (p < 0.001) and higher intraoperative need of catecholamines (p = 0.03). Delirious patients showed more inflammatory response (p < 0.001). AChE and BChE values were mainly inside the norm. Patients with values outside the norm did not have POD more often than others. Regarding AChE and BChE patients did not differ in having delirium or not (p > 0.10). Conclusions: Postoperative measurement of AChE and BChE did not discern between patients with and without POD. The effect of the cardiac surgical procedure on AChE and BChE remains unclear. Further studies with patients in cardiac surgery are needed to evaluate a possible combination of delirium and the cholinergic transmitter system. There might be possible interactions with AChE/BChE and blood products and the use of cardiopulmonary bypass, which should be investigated more intensively. Trial registration: German Clinical Trials Register, DRKS00006217.