Effect of perioperative continuous femoral nerve block on postoperative cognitive dysfunction in elderly patients with femoral neck fractures

Abstract

Objective To evaluate the effect of perioperative continuous femoral nerve block on postoperative cognitive dysfunction(POCD)in elderly patients with femoral neck fractures. Methods Sixty American Society of Anesthesiologists physical status Ⅱ or Ⅲ patients of both sexes, aged 65-90 yr, scheduled for femoral head replacement under combined spinal-epidural anesthesia, were divided into 2 groups(n=30 each)using a random number table: patient-controlled femoral nerve block for analgesia(PCNA)group and patient-controlled intravenous analgesia(PCIA)group.When the patients were diagnosed with femoral neck fractures after admission to hospital in two groups, patients received continuous PCNA under nerve stimulator guidance until 48 h after operation in group PCNA, and fentanyl was continuously injected for analgesia until 48 h after operation in group PCIA.Neuraxial anesthesia was performed at L3, 4 interspace, 2 ml cerebrospinal fluid was extracted after successful subarachnoid puncture to detect the concentrations of Aβ-42 and tau, and the ratio of Aβ-42 to tau was calculated.The patient′s cognitive function was assessed using Mini-Mental State Examination before analgesia and at 7 days after operation, and the occurrence of POCD was recorded. Results The ratio of Aβ-42 to tau in cerebrospinal fluid was significantly lower, and the incidence of POCD was higher at 7 days after operation in group PCIA than in group PCNA(P<0.05). Conclusion Perioperative continuous femoral nerve block can decrease the development of POCD in elderly patients with femoral neck fractures. Key words: Nerve block; Femoral nerve; Cognition disorders; Aged