Monitoring cerebral oxygen saturation in elderly patients undergoing general abdominal surgery: a prospective cohort study

Background and objectives: The aim of this prospective, observational study was to evaluate changes in regional cerebral oxygen saturation (rSO(2)) and incidence of intraoperative cerebral desaturation in a cohort of elderly patients undergoing major abdominal surgery. Methods: rSO(2) was continuously monitored on the left and right si des of the forehead 60 patients older than 65 yr (35 males and 25 females; ASA II-III; age: 72 +/- 5 yr; without out pre-existing cerebral pathology, and baseline Mini Mental State Examination (MMSE) score > 23) undergoing sevoflurane anaesthesia for major abdominal, non-vascular surgery > 2 h. Results: Baseline rSO(2) was 63 +/- 8%; cerebral desaturation (rSO(2) decrease < 75% of baseline or < 80% in case of baseline rSO(2) < 50%) occurred in 16 patients (26%). The MMSE decreased from 28 +/- 1 before surgery to 27 +/- 2 on 7th postoperative day (P = 0.05). A decline in cognitive function (decrease in MMSE score >= 2 points one week after surgery as compared to baseline value) was observed in six patients without intraoperative cerebral desaturation (13.6%) and six patients who had intraoperative cerebral desaturation (40%) (P = 0.057) (odds ratio: 4.22; CI95%: 1.1-16). Median (range) hospital stay was 14 (5-41) days in patients with an area under the curve of rSO(2) < 50% (AUC(rSO2 < 50% >)) 10 min%, and 10 (4-30) days in those with an AUC(rSO2 < 50%) < 10 min% (P = 0.0005). Conclusions: In a population of healthy elderly patients, undergoing non-vascular abdominal surgery cerebral desaturation can occur in up to one in every four patients, and the occurrence of cerebral desaturation is associated with a higher incidence of early postoperative cognitive decline and longer hospital stay.