Does Bispectral index monitoring during anesthesia provide benefit for elderly patients?

INTERVENTION: In study groups Bispectral index is recorded in all subjects but only available for guiding administration of anesthetics in the "open" group as opposed to the "concealed" group in which data is recorded for subsequent analysis. Additional control patients not undergoing surgery were recruited to establish the learning effect and natural variation in performance over time in the cognitive testing for postoperative cognitive dysfunction. CONDITION: Improved outcome after anesthesia by more precise administration of anesthetics in relation to individual need as assessed by bispectral index monitoring. ; Surgery ; Anesthesia PRIMARY OUTCOME: Postoperative cognitive dysfunction day 7 after surgery, global cardio‐vascular outcome score (based on 10 subparameters), and global socio‐economic outcome score ( based on 8 subparameters) SECONDARY OUTCOME: Intraoperative blood loss, net fluid and blood balance, urine production first 6 h postoperatively, postoperative hypoxemia (defined as SpO2 below 90%), increase in C‐reactive protein postoperative day 3, weight gain postoperative day 3, awareness, 7 subparameters reflecting postoperative cognitive decline as described by Moller et al. (Lancet 1998; 351: 857‐61), increase in Troponin‐I 12‐24 h after surgery, increase in Troponin‐I 72 h after surgery, average intraoperative mean arterial blood pressure, duration of heart rate deviating >20% from baseline intraoperatively, duration of heart rate deviating >20% from baseline postoperatively, duration of systolic arterial blood pressure deviating >20% from baseline intraoperatively, duration of systolic arterial blood pressure deviating >20% from baseline postoperatively, duration of intraoperative inotropic support, number of patients given inotropic support postoperatively, duration of inotropic support postoperatively, age corrected average MAC‐fraction of sevoflurane administered during anesthesia, duration of stay at the postoperative care unit, number of påatioents admitted to the ICU postoperatively, duration of sotal stay at the postoperative care unit and intensive care unit, length of hospital stay, number of patients being discharged to home, 30‐day survival, 1‐year survival. INCLUSION CRITERIA: 1. Aged over 70, both gender 2. Anticipated duration of surgery over 90 minutes 3. Being able to communicate in Swedish 4. No overt hearing or reading difficulties