Encephalopathy Associated with Sepsis

Abstract

Whilst many investigators agree that a ‘clouding of consciousness’ is perhaps the most common disturbance in organ function associated with septic shock, proven severe systemic sepsis or even the more nebulous ‘septic syndrome’, it is still not clear exactly what are the relationships between fever, acute confusional states (often described loosely as a form of ‘delirium’ and most commonly observed in the elderly who may well be hypothermic), stupor and frank coma and how these different disturbances in brain function relate to so-called ‘septic encephalopathy’ and other organ system dysfunction [1]. One problem that is inherent in all the recent discussions of ‘multiple organ failure’, ‘critical illness’ associated with sepsis and trauma etc. has been the unstated supposition that one identifiable mechanism can account for all the metabolic and functional disturbances seen in these patients [2]. This, in my opinion, is patently not the case and when ‘septic encephalopathy’ is considered in isolation from other organ failure, it becomes apparent that various processes are at work at different times of the illness which can account for the observed disturbances in brain function. Drugs, alcohol and alcohol (or other drug) withdrawal obviously confuse the issue (and the patient!); this subject has been dealt with elsewhere. Drug-induced brain dysfunction is one important factor in the apparent reversibility of ‘septic encephalopathy’. It probably accounts fot the majority of patients with severe sepsis and abnormal brain function who also have disturbances in hepatic and renal function and who suddenly ‘wake up’ as their underlying condition improves. At the same time, their medications are stopped whilst there are spontaneous improvements in hepatic and renal drug clearance. Thus it is difficult to identify patients suffering only from ‘septic encephalopathy’ and this limits our ability to study the pathogenesis.