Perioperative Continuous Femoral Nerve Block Reduces Postoperative Cognitive Dysfunction of High-Risk Patients with Femoral Neck Fracture: Evidence from a Retrospective Propensity-Matched Study.

BACKGROUND Elderly patients often suffer from postoperative cognitive impairment which increases mortality, morbidity, and the economic burden. However, how continuous femoral nerve block (cFNB) influence the incidence of postoperative cognitive dysfunction (POCD) has never been reported. This study tried to explore how cFNB affects the incidence of POCD among low-risk and high-risk patients with femoral neck fractures. MATERIAL AND METHODS We conducted a retrospective propensity score-matched study and allocated matched patients (n=172) with femoral neck fractures into the cFNB group (n=86) and the control group (n=86). Demographical and clinical data were collected and compared, including the visual analog scale (VAS) score, the morphine consumption, and the POCD incidence. Subgroup analysis of high-risk patients (Mini-Cog score ≤2) and low-risk patients (Mini-Cog score ≥3) was also carried out. RESULTS After matching, baseline characteristics of 2 groups were comparable between the 2 groups (all P>0.05). Compared with the control group, the cFNB group had significantly lower visual analog scale (VAS) score and morphine consumption in the postoperative 3 days (P<0.05). For high-risk patients, the Kaplan-Meier survival curve suggested that the incidence of POCD the cFNB group was significantly lower than the control group (P=0.005), without statistical difference for total or low-risk patients (P>0.05). Multivariate Cox hazard regression analysis showed that the adoption of cFNB conferred a protective effect on POCD (HR=0.556, 95% CI 0.316-0.981, P=0.043). CONCLUSIONS For patients undergoing femoral neck fracture surgery, perioperative cFNB administration is useful in decreasing the incidence of POCD, especially for high-risk patients with a Mini-Cog score equal to or less than 2 points.