The aim of the study is a prediction or an earlier detection of CIP in critically ill patients before nerve conduction studies are able to diagnose CIP. We hypothesize that upregulated circulating neurotoxic factors in human serum of critically ill patients cause neuronal damage and play an important role in the pathogenesis of CIP. Time from upregulation of neurotoxic factors to the clinical appearance of neuronal damage (CIP) is unknown.