The impact of the type of anaesthesia on cognitive status and delirium during the first postoperative days in elderly patients

Background and objectives: Postoperative confusion and delirium is a common complication in the elderly with a poorly understood pathophysiology. The aim of this study was to examine whether the type of anaesthesia (general or regional) plays a role in the development of cognitive impairment in elderly patients during the immediate postoperative period. Methods: Forty-seven patients >60 yr of age and undergoing major surgery were randomly allocated to receive either regional or general anaesthesia. The mental status of the patients was assessed preoperatively and during the first three postoperative days with the Mini Mental State Examination. The incidence of delirium was also examined during the same period with the use of DSM III criteria. Results: Overall, during the first three postoperative days, the mean Mini Mental State Examination score decreased significantly (P < 0.001). However, this decline was very significant only in patients assigned to receive general anaesthesia (P < 0.001) compared to regional anaesthesia. Nine patients developed delirium but the type of anaesthesia did not affect its incidence. The only important factor for the development of delirium was pre-existing cardiovascular disease irrespective of anaesthesia type (P < 0.025). Conclusions: Elderly patients subjected to general anaesthesia displayed more frequent cognitive impairment during the immediate postoperative period in comparison to those who received a regional technique.