[Delirium after surgery with extra-corporeal circulation]

The recent literature still reports a high incidence of delirium in patients operated with extracorporeal circulation. This syndrome is found more often in patients over 50 years and in patients with a previous history of delirium, alcoholism, drug addiction or cerebral damage and is more frequent after valvular than after coronary surgery. It is also often observed in patients who present major post-operative complications. Attention and concentration capacity are characteristically modified (diminished most of the time) with or without faulty perception (hallucinations), sleep alterations, incoherent language, apathy or agitation. Disorientation and memory troubles are common. Delirium appears within a few hours or a few days of the surgery, its evolution is fluctuant and generally benign. A retrospective study at the Montreal Heart Institute showed an incidence of 2.98 per cent (84 cases/2811 open heart surgery cases) over the last four years. The mean age of these patients was 57.5 years (versus 50.4 for patients without delirium). Major post-operative complications were found in 37 (44 per cent) of these 84 patients. The incidence was lower (1.45 per cent) in coronary than in valvular (4.6 per cent) surgery cases. Several explanations are presented to explain this low incidence.