DELIRIUM AND COGNITIVE DISORDERS AFTER CARDIAC OPERATIONS - RELATIONSHIP TO PREOPERATIVE AND INTRAOPERATIVE QUANTITATIVE ELECTROENCEPHALOGRAM

We examined the incidence of delirium and cognitive disorders after ca rdiac operations and the related risk factors. The value of pre- and i ntraoperative QEEG was determined. Using the Mini-Mental State Examina tion and the Saskatoon Delirium Checklist, 321 patients were tested du ring the immediate postoperative period. Forty-four patients (14%) sho wed delirium, 68 (23%) cognitive disorders and 26 (9%) both. Significa nt risk factors for the development of cognitive disorders were age gr eater than or equal to 70 yr, female gender, duration of cardiopulmona ry bypass greater than or equal to 2.5 h and aorta-cross-clamping > 70 min. Risk factors for delirium were age greater than or equal to 70 y r, female gender and Hb < 5 mmol l(-1) intraoperatively. The preoperat ive QEEG showed significant differences between the groups with and wi thout a cognitive disorder, while the intraoperative QEEG showed signi ficant differences between the groups with and without delirium. Diffe rent risk factors for delirium and cognitive disorders are a possible explanation for the controversies in the literature, where neuropsycho logic complications were grouped together. A low intraoperative Hb is an important risk factor for the development of delirium and can he tr eated. The preoperative QEEG may have prognostic significance in the o ccurrence of cognitive disorders, while the intraoperative QEEG may ha ve prognostic significance in the occurrence of delirium.