Impact of tourniquet application on postoperative delirium in elderly patients undergoing total knee arthroplasty: a randomized clinical trial.

BACKGROUND

Tourniquet is widely used in total knee arthroplasty (TKA), but its impact on postoperative delirium (POD) remains unclear. The purposes of this study were to investigate the impact of tourniquet application on POD in elderly patients TKA and to explore the possible mechanisms associated with POD.

MATERIALS AND METHODS

In this prospective, single-center randomized clinical trial study, 313 patients scheduled for single TKA under general anesthesia were randomly assigned to groups with or without a limb tourniquet. The primary outcome was the incidence of POD within postoperative 7 days. Secondary outcomes were the levels of hypoxia-inducible factor-1α (HIF-1α), tumor necrosis factor-alpha, superoxide dismutase (SOD), and S100β protein (S100β) measured postoperative 30 minutes and 24 hours, blood loss, pain score, the time to first postoperative ambulation, postoperative hospitalization, postoperative complications, and adverse events.

RESULTS

The incidence of POD in tourniquet group was significantly higher than that in no tourniquet group (19.1% vs. 9.6%, relative risk 1.12, 95% confidence interval: 1.02-1.23, P = 0.018). The serum level of HIF-1α was higher at postoperative 30 minutes and 24 hours and SOD was lower at postoperative 24 hours in tourniquet group compared with no tourniquet group. The incidence of postoperative complications and adverse events were comparable in both groups.

CONCLUSION

We concluded that tourniquet application during TKA increased the incidence of POD within postoperative 7 days in older patients, and increased serum level of HIF-1α and decreased level of SOD, which indicated that they may be potential targets for preventing and treating POD.