Effects of lumbar plexus-sciatic nerve block combined with sevoflurane on cognitive function in elderly patients after hip arthroplasty: study protocol for a prospective, single-center, open-label, randomized, controlled clinical trial

Background: Elderly patients often suffer from postoperative cognitive dysfunction after total hip arthroplasty, but the precise mechanism remains unclear. Sevoflurane regulates the concentration of basic fibroblast growth factor in the brain, but it is not known whether sevoflurane can decrease cognitive dysfunction after hip arthroplasty. We hypothesized that lumbar plexus-sciatic nerve block combined with sevoflurane could reduce the incidence of cognitive dysfunction in elderly patients after hip arthroplasty. Methods/Design: We conducted a prospective, single-center, open-label, randomized, controlled clinical trial at the Affiliated Hospital, Qinghai University, China. Seventy elderly patients undergoing unilateral total hip arthroplasty were randomized into two groups. All patients underwent endotracheal intubation and mechanical ventilation. In the experimental group, a lumbar plexus-sciatic nerve block was performed and general anesthesia was maintained with sevoflurane. In the control group, general anesthesia was maintained with intravenous propofol. Outcomes were measured preoperatively and on the first and third postoperative days. The primary outcome measure was the Mini-Mental State Examination, and the secondary outcomes were the Montreal Cognitive Assessment, serum basic fibroblast growth factor concentration, intraoperative blood loss, and operation time. The other outcome was the incidence of intraoperative and postoperative adverse events. Discussion: This trial examined whether lumbar plexus-sciatic nerve block combined with sevoflurane reduced the incidence of cognitive dysfunction in elderly patients after hip arthroplasty, documented the changes in serum basic fibroblast growth factor concentration, and further explored the therapeutic mechanism of sevoflurane. Trial registration: ClinicalTrials.gov identifier: NCT03162861. Ethics: The study protocol has been approved by the Ethics Committee of Affiliated Hospital of Qinghai University of China. All protocols will be in accordance with Declaration of Helsinki, formulated by the World Medical Association. Informed consent: Written informed consent was provided by participants prior to enrollment in the trial.