Postoperative cognitive dysfunction in elderly patients. Based on the publication of the ISPOCD 1 study group in Lancet (1998) 351: 857-861

Objective: Cognitive dysfunction is a known problem after operations and ma y be especially relevant in the elderly. The aim of this international mult icentre study was to investigate short- and long-term cognitive dysfunction in elderly patients and to elucidate the relevance of hypoxaemia and hypot ension as causative factors. Methods: 1218 patients aged 60 years and older and scheduled for major non- cardiac surgery under general anaesthesia were investigated. Oxygen saturat ion was measured by continuous pulse oximetry before surgery and throughout the day of and the fi rst 3 nights after surgery. Blood pressure was recor ded every 3 minutes during the operation and every 15-30 min for the rest o f that day and night. Cognitive testing was performed before and 1 week and 3 months after the operation. Cognitive dysfunction was identified with ne uropsychological tests compared with controls recruited from the UK (n=176) and the same countries as study centres (n=145). Results: Postoperative cognitive dysfunction was present in 25.8% of patien ts 1 week after surgery and in 9.9% 3 months after surgery, compared with 3 .4% and 2.8%, respectively, of the UK controls. Increasing age and duration of anaesthesia,little education,a second operation, postoperative infectio ns,and respiratory complications were the risk factors for early postoperat ive cognitive dysfunction, but only age was a risk factor for long-term pos toperative cognitive dysfunction. Hypoxaemia and hypotension were not signi ficant risk factors at any time. Conclusion:With this investigation longterm cognitive dysfunction could be proven definitively for elderly patients after major operations under gener al anaesthesia. No factors with prophylactic or therapeutic influence were detectable so that aetiology and pathophysiology of POCD could not be furth er determined.