Effects of oxycodone applied for patient-controlled analgesia on postoperative cognitive function in elderly patients undergoing total hip arthroplasty: a randomized controlled clinical trial

Background Postoperative cognitive dysfunction (POCD) is a common complication after orthopedic surgery, which is not conducive to the prognosis of the elderly. Aims We performed this study to investigate the effects of oxycodone applied for patient-controlled intravenous analgesia (PCIA) on postoperative cognitive function in elderly patients after total hip arthroplasty (THA). Methods Ninety-nine participants were enrolled and allocated into two groups: oxycodone group (group O) and sufentanil group (group S). The primary outcome was the incidence of POCD, diagnosed according to the changes in the Mini-mental status examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores. The secondary outcomes included the plasma levels of S-100B protein and neuron-specific enolase (NSE), the amount of postoperative analgesic consumption and the incidence of adverse reactions. Results The incidence of POCD was significantly lower in patients receiving oxycodone up to the 3rd postoperative day (POD, 1st POD 27.3% vs. 51.1%, P = 0.021; 3rd POD 20.5% vs. 40.0%, P = 0.045), as compared to patients receiving sufentanil. The MMSE and MoCA scores of both groups decreased to varying degrees. However, compared with group S, the MMSE scores at 1st POD, 3rd POD, 5th POD and 7st POD in group O were higher than that in group S, while MoCA scores at 1st POD, 3rd POD and 5th POD in group O were higher. Compared with group S, the plasma levels of S-100B protein in group O at 4 h, 8 h, 12 h post-surgery were lower. While the plasma levels of NSE in group O at 4 h, 8 h, 12 h, 24 h post-surgery were lower. Number of PCIA boluses and consumption of analgesic drug during the first two POD were similar between two groups. However, postoperative incidence of nausea, vomiting and pruritus was significantly lower in patients receiving oxycodone. Conclusion Oxycodone applied for PCIA in elderly patients after THA could reduce the incidence of POCD, improve postoperative cognitive function and decrease the adverse reactions.