Cerebral oximetry and cognitive dysfunction in elderly patients undergoing surgery for hip fractures: a prospective observational study

Aim: This study was conducted to examine perioperative cerebral oximetry changes in elderly patients undergoing hip fracture repair and evaluate the correlation between regional oxygen saturation (rSO(2)) values, postoperative cognitive dysfunction (POCD) and hospital stay.

Materials and methods: This prospective observational study included 69 patients. Data recorded included demographic information, rSO(2) values from baseline until the second postoperative hour and Mini Mental State Examination (MMSE) scores preoperatively and on postoperative day 7. MMSE score ≤23 was considered evidence of cognitive dysfunction. Postoperative confusion or agitation, medications administered for postoperative agitation, and hospital length of stay were also recorded. Data were analyzed with Student's t-test, Pearson's correlation or multiple regression analysis as appropriate.

Results: Patient age was 74±13 years. Baseline left sided rSO(2) values were 60±10 and increased significantly after intubation. Baseline rSO(2) L<50 and <45 was observed in 11.6% and 10.1% of patients respectively. Perioperative cerebral desaturation occurred in 40% of patients. MMSE score was 26.23 ± 2.77 before surgery and 25.94 ± 2.52 on postoperative day 7 (p=0.326). MMSE scores ≤ 23 were observed preoperatively in 6 and postoperatively in 9 patients. Patients with cognitive dysfunction had lower preoperative hematocrit, hemoglobin, SpO(2) and rSO(2) values at all times, compared to patients who did not. There was no correlation between rSO(2) or POCD and hospital stay. Patients with baseline rSO(2) <5 required more medications for postoperative agitation.

Conclusion: Cognitive dysfunction occurs preoperatively and postoperatively in elderly patients with hip fractures, and is associated with low cerebral rSO(2) values.