AChE-activity in critically ill patients with suspected septic encephalopathy: a prospective, single-centre study

Abstract

Background Up to 70% of septic patients develop a diffuse brain dysfunction accompanying with an increase in mortality, which is referred to as “septic associated encephalopathy”. Neuroinflammation as well as a disturbance of cholinergic transmission are assumed to be the causes of both delirium and septic associated encephalopathy. A possible change in cholinergic activity can be objectified by measuring the erythrocytic acetylcholinesterase activity. It has been shown, however, that the acetylcholinesterase activity, if only single measurements are carried out, is controversial in its significance. Therefore, we wanted to test the hypothesis whether a longitudinal analysis of acetylcholinesterase activity in critically ill patients can help to diagnose a suspected septic-associated encephalopathy and whether acetylcholinesterase activity differs in comparison to non-septic patients.Methods In this prospective, observational, single-center study, 175 patients, admitted to the surgical Intensive Care Unit of the University hospital Ulm, Germany, were included. 45 patients were septic, 130 patients were non septic. All patients were examined daily for the presence of delirium using the CAM-ICU. Daily measurement of the acetylcholinesterase activity was performed in all patients. The acetylcholinesterase activity was analyzed over time using a linear regression model taking into account repeated measurements. By using a time adjusted model, the effect of further possible predictors of acetylcholinesterase activity was analyzed too. For nonparametric distributions quantitative data were compared using Wilcoxon matched-pairs test. For the analysis of the independent samples the Mann-Whitney test was performed. Results In approximately 90% of the septic patients with suspected septic associated encephalopathy a statistically significant, time-dependent in- or decrease in acetylcholinesterase activity could be demonstrated over a period of at least 5 consecutive days.Conclusion The longitudinal measurement of acetylcholinesterase activity over several consecutive days revealed a shift compared to baseline values exclusively in septic patients with supposed septic associated encephalopathy. Therefore, longitudinal measurement of acetylcholinesterase activity may help to diagnose septic associated encephalopathy in patients with sepsis and accompanying delirium symptoms.Trial registration Retrospectively registered at German Clincial Trials Register, registration number DRKS 00020542, date of registration: January 27, 2020