Intraoperative Sleep Spindle Activity and Postoperative Sleep Disturbance in Elderly Patients Undergoing Orthopedic Surgery: A Prospective Cohort Study.

PURPOSE

This study aimed to investigate the relationship between intraoperative sleep spindle activity and postoperative sleep disturbance (PSD) in elderly orthopedic surgery patients.

PATIENTS AND METHODS

In this prospective observational cohort study, we collected intraoperative electroencephalography (EEG) data from 212 elderly patients undergoing orthopedic surgery from May 2023 to December 2023. We used the Athens Insomnia Scale to assess sleep quality on postoperative day (POD) 1 and POD 3 and analyzed the correlation between intraoperative sleep spindle activity and PSD through logistic regression.

RESULTS

The incidence of PSD was 65.6% on POD 1 and 41.9% on POD 3. On the first day, there were no significant differences in intraoperative sleep spindle characteristics between PSD and non-postoperative sleep disturbance (non-PSD) patients. However, by the third day, PSD patients showed lower sigma power compared to non-PSD patients, as well as lower spindle density in the bilateral frontopolar (Fp1/Fp2) and bilateral temporal (F7/F8) channels, with shorter average spindle duration ( < 0.05). Multivariate logistic regression analysis suggested that the average spindle density in F7/F8 channels (OR 0.543, 95% CI 0.375-0.786; = 0.001) was an independent risk factor for PSD on POD 3. Furthermore, Mini-Mental State Examination (MMSE) could independently predict PSD on POD 1 (OR 0.806, 95% CI 0.656-0.991; = 0.041) and POD 3 (OR 0.701, 95% CI 0.562-0.875; = 0.002). Pain on movement and at rest were independently associated with PSD on POD 1 (OR 1.480, 95% CI 1.200-1.824; < 0.001) and POD 3 (OR 1.848, 95% CI 1.166-2.927; = 0.009), respectively.

CONCLUSION

Intraoperative mean spindle density in the F7/F8 channels was an independent risk factor for PSD on POD 3 in elderly patients undergoing orthopedic surgery. MMSE and postoperative pain also independently increased the risk of PSD.