Objective  To investigate the effect of dexmedetomidine combined with fentanil on postoperative sleep quality and cognitive function in elderly patients with patient-controlled intravenous analgesia(PCIA).

  Methods  Forty elderly patients underwent thoracic surgery were randomly divided into control group(fentanil group, n=20) and experimental group C (fentanil plus dexmedetomidine group, n=20), The control group was mixed 15 μg/kg fentanil and 5 mg tropisetron into 100 mL of normal saline in patient-controlled intravenous analgesia pump, and experimental group contained 15 μg/kg fentanil, 1.0 μg/kg dexmedetomidine and 5 mg tropisetron in 100 mL of normal saline. The pump was withdrawn after 48 h. The total steep time, sleep quality were recorded at 1 d before surgery and on the day of surgery, and at 3 d after surgery. The Mini-Mental Status Examination (MMSE) were recorded at 1 d before surgery and 1, 3, 7 d after surgery, and the incidence of postoperative cognitive dysfunction was observed.

  Results  Compared with control group, the sleep time of experimental group on the surgery day and at 2 d after surgery was longer (P < 0.05); the sleep quality were significantly higher(P < 0.05); the MMSE scores of experimental group on the first and third postoperative day were higher(P < 0.05), and the incidence of POPD was lower than that in the control group(P < 0.05).

  Conclusion  Dexmedetomidine combined with fentanil administered for postoperative analgesia in elderly patients shows better efficacy in improvement of sleep status, and improve the postoperative cognitive function.