Delirium and dehydration: some fluid for thought?

Delirium is a frequent complication of advanced cancer. It is characterized by cognitive deficits and behavioral disturbance, and therefore can potentially result in severe symptom distress and impeded communication between patient and family and between patient and medical staff. The reversibility of delirium depends on its underlying causes. Delirium is multifactorial in origin, and precipitating or contributory factors include dehydration and hypovolemia. Much of the debate concerning the role of hydration in advanced cancer has centered on symptoms such as thirst, and ethical issues such as parenteral hydration and its association with prolongation of life, with the association between hydration status and delirium largely excluded. This review examines the latter association in the light of recent studies. It also provides an outline of relevant pathophysiology and clinical assessment, a decision-making framework and a practical approach to the techniques of assisting hydration. This will hopefully help physicians and families in weighing up the merits of assisted hydration in an individual context and help them to achieve a consensus on the role of hydration that is consistent with the goals of care.