Effect of intraoperative methylene blue on postoperative delirium in elderly patients undergoing joint replacement: a randomized controlled trial.

BACKGROUND

Postoperative delirium (POD) is one of the most prevalent postoperative complications after joint replacement surgery that has great impact on patients' outcomes. Methylene blue (MB) is reported to decrease the incidence of POD. In the current study, the authors investigated whether MB would reduce the incidence of POD in elderly patients undergoing joint replacement surgery.

MATERIAL AND

METHODS

In total, 217 elderly patients undergoing joint replacement surgery were randomly assigned to the MB group ( n = 109) or the control group ( n = 108). The MB group received a continuous intravenous infusion of 50 mL of a mixture of 2 mg/kg MB and 5% glucose solution within 60 minutes of anesthesia induction, and the control group received a continuous infusion of an equivalent volume of 5% glucose solution. The rate of POD in both groups, 5 days following surgery, was the primary endpoint. The secondary outcomes were delirium characteristics, postoperative pain score, telephone interview for cognitive status-modified score 1 month after surgery, and the type and incidence of adverse events (AEs).

RESULTS

A total of 31 patients (14.3%) experienced POD. The incidence of POD in the MB group was significantly lower than that in the control group (8.3% vs. 20.4%, hazard ratio = 0.39; 95% confidence interval: 0.173-0.858; P = 0.024). Postoperative fever was substantially more common in the MB group (16.5%) than in the control group (7.4%, P = 0.039). Nevertheless, the proportions of patients with other AEs were similar between the two groups.

CONCLUSIONS

In older patients undergoing joint replacement surgery, intraoperative intravenous infusion of 2 mg/kg MB can lower the incidence of POD during hospitalization, but it does not significantly increase the incidence or severity of AEs.