Neurocognitive Disorders After Major Surgery in Elderly

Information provided by the BIS (Medtronic, Canada) monitor will guide the volatile anesthetic administration in the EEG-guided group to maintain a BIS value between 40 and 60, a Suppression Ratio (SR; % of time with suppressed brain electrical activity) at 0% or the closest, a direct EEG display without any suppression time and a spectrogram (DSA or density spectral array) with most of the EEG wave frequency within the Alpha (8-12Hz), Theta (4-8Hz) and Delta (0.5-4Hz) frequencies.

In the standard care group, the age-adjusted Minimum Alveolar Concentration (MAC-age) of sevoflurane will be kept at \[0.8-1.2\] MAC.