Delirium after Cardiac Surgery

Abstract

Delirium is a transient and fluctuating organic mental syndrome of acute onset, characterized by a global impairment of cognitive functions, a reduced level of consciousness, attentional abnormalities, increased or decreased psychomotor activity and a disordered sleep-wake cycle (Lipowski, 1990). Cardiac surgery with cardiopulmonary bypass (CPB) has traditionally been associated with a particularly high rate of postoperative delirium (Smith and Dimsdale, 1989), supposed to be due to cytotoxic oedema induced by cerebral microemboli, hypoperfusion or haemodilution (Editorial, 1989). This psychiatric complication is associated with increased morbidity, high mortality, prolonged hospital stay and poor functional recovery (van der Mast, 1994). Little is known about possible predictive factors and mediating pathophysiological mechanisms. Following on earlier research suggesting a role of reduced plasma tryptophan in postcardiotomy delirium (van der Mast, 1991), we prospectively examined the contribution of disturbances in the plasma concentrations of aminoacids, in relation to a catabolic state, among patients undergoing elective cardiac surgery.