The causative role of physiological parameters on cognitive functions of geriatric patients after regional- or general anaesthesia

Objective: The aim of the present study was to show the influence of the pa rameters of gas exchange (arterial oxygen pressure paO(2), arterial oxygen saturation SatO(2)) and haemodynamics (arterial systolic and mean blood pre ssure RRs and MAP) on the restitution of cognitive functions in geriatric p atients scheduled for elective hip arthroplasty. Methods: A total of 30 patients (70 years, ASA II) were randomized to be op erated either in regional anaesthesia (n=15) or general anaesthesia (n=15). PaO2 (by capillary blood gas analysis), RRs and MAP (by oscillometry) were measured 15 and 90 minutes after arrival in the recovery unit (t1 and t2), 24 and 72 hours postoperatively (t3 and t4),and cognitive functions were t ested. Intraoperatively, throughout the day and the first night after surge ry we measured satO(2) by continous pulse oximetry. We recorded MAP and RRs by oscillometry every 3 minutes during the operation and every 15 minutes for the rest of that day and night. Results: The parameters of gas exchange and haemodynamics did not differ am ong the groups. PaO2 was significantly reduced in both groups compared to b aseline 24 hours postoperatively (t3) and remained low until 72 hours posto peratively (t4). Nearly all cognitive functions were significantly reduced in both groups compared to baseline 15 and 90 minutes after arrival in the recovery unit (t1 and t2), but recovered on the first post operative day (t 3). Both groups kept deficits in verbal memory and reading capacity up to t he third postoperative day (t1). There was no correlation between the physi ological parameters and the restitution of the tested cognitive functions. Conclusion: The restitution of cognitive functions during the first three p ostoperative days in geriatric patients scheduled for elective hip surgery does not depend on the anaesthetic technique. According to our results regi onal anaesthesia does not show any advantage for geriatric patients undergo ing elective hip arthroplasty.