[Delirium following heart surgery with extracorporeal circulation: clinical aspects and observations in a specialized center]

Delirium after cardiac surgery: a critical review

Numerous articles have been published investigating the incidence of and risk factors for delirium after cardiac surgery. Smith and Dimsdale reviewed the literature on postcardiotomy delirium in 1987 using a meta-analysis of 44 research studies. However, doubts about their methods and results caused the authors to re-examine the literature using these 44 references as well as computerized literature searches to gather research and review papers from medical journals. Delirium after cardiac surgery appeared to be ill-defined in most of these studies. The methods and instruments used to assess delirium proved to be very different, and the patient samples were rather heterogeneous. Therefore, in most cases, the results are not comparable. Only a small number of the studies that were examined fit the criteria for statistical meta-analysis. On the basis of our analysis, a tentative conclusion may be drawn that the incidence of postcardiotomy delirium has declined slightly and that no strong risk factors have yet been identified.

Delirium: 100 cases

One hundred consecutive cases of delirium seen in a psychiatric consultation service of a general hospital are discussed. Two thirds of the patients came from pneumology and cardiology since the hospital serves as a regional thoracic center. The frequency of delirium was 12.6% of consultations: three men were seen for every one woman; 80% of cases were over fifty years of age. The clinical aspects of delirium are studied according to DSM-III criteria to evaluate: a) the frequency of the symptoms, b) the temporal course of the disorder, c) any clinical characteristic of delirium linked with potential etiological factors, d) the role of anxiety.

[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.