Delirium in the critically ill adult: an overview of current theory and practice

Delirium is an acute encephalopathic syndrome that is highly prevalent in critically ill adult patients. The occurrence of delirium carries serious negative implications for patient outcomes and is a frightening and distressing experience for patients. The significance of delirium occurrence as an indicator of acute illness severity and clinical deterioration is well recognised. This is reflected in the inclusion of altered mental status in a number of national illness severity scoring systems. An awareness and understanding of delirium in the critically ill adult is therefore of relevance to all adult nurses. This article provides an overview of delirium in the critically ill adult patient, discussing current knowledge and recommended practice across key areas. These include the definition and classification of delirium; the implications of delirium for patient outcomes and experience; the aetiology and pathophysiology of delirium; delirium assessment tools used with critically ill patients and recommended approaches to prevention and management. The article will enable practitioners to develop a current understanding of key areas relating to delirium in the critically ill adult patient and encourage a reflective approach to considering the implications for practice.