A study on the relationship between the intraoperative regional cerebral oxygen saturation trends and cognitive decline after lower limb surgeries in elderly patients

Abstract

Background: The purpose of the study was to assess whether there is a correlation of cerebral oxygenation levels after spinal anaesthesia with the decline in cognitive function. Materials & Methods: After thorough PAC of the patients, patients were administered Spinal anaesthesia and haemodynamic parameters (SpO2, BP, HR) were monitored. Also cerebral oxygenation was monitored through NIRS and rSO2 values were tabulated intra operatively. Neurocognitive battery of tests were presented to the patient both pre-operatively and intra-operatively and MMSE Memory and Executive functions were compared pre-operatively and post operatively and their variations were correlated with rSO2. Results: POCD was seen in 16% of patients in immediate post operative day (D0) which decreased to 12% on D10. Cerebral oxygen saturation (rSO2 ) was monitored in 50 patients undergoing lower limb surgery with central neuraxial anaesthesia. The mean value of rSO2 of the right side reduced from 65.04 to 59.56 after giving central neuraxial block which further reduced to 57.72 after commencement of surgery which remained the same throughout. At the end of the procedure rSO2 increased to 60.16 and further returned to near-baseline value of 64.46 at 30 mins post operatively. Simlarly, mean rSO2 of the left side was 64.94 at baseline which reduced to 60.12 after central neuraxial block and stayed at 56.98 till end of procedure which increased to 62.28 at 30 minutes post operatively. MMSE score at baseline (pre-operatively) was 25.92±1.724 which reduced to 24.98±3.820 on post-operative day at D0,which subsequently increased slightly to 26.26±1.871 on Day 5 and came to near baseline values of 25.88±1.734 on Day 10. Memory value at baseline was a mean of 7.68 (on a scale of 12) with a standard deviation of ±0.999 and on Day 0 post operatively was 7.48±0.953 and it came back to 7.58±1.032 on Day 5 and came to near baseline values of 7.66±1.002 on Day 10 post operatively. There was weak correlation of rSO2 variations with POCD (MMSE scores, Memory values and Executive function). Conclusion: Incidence of POCD is in 12% of patients during D10 post operatively. rSO2 decreased intra-operatively. There was no strong correlation with decline in rSO2 values during intra-operative period with development of POCD.